The Magazine of the Arnold Arboretum *« ^ 5 W | amolaia The Magazine of the Arnold Arboretum VOLUME 72 • NUMBER 1 • 2014 CONTENTS Arnoldia (ISSN 0004-2633; USPS 866-100) is published quarterly by the Arnold Arboretum of Harvard University. Periodicals postage paid at Boston, Massachusetts. Subscriptions are $20.00 per calendar year domestic, $25.00 foreign, payable in advance. Remittances may be made in U.S. dollars, by check drawn on a U.S. bank; by international money order; or by Visa, Mastercard, or American Express. Send orders, remittances, requests to purchase back issues, change-of-address notices, and all other subscription-related communica- tions to Circulation Manager, Arnoldia, Arnold Arboretum, 125 Arborway, Boston, MA 02130- 3500. Telephone 617.524.1718; fax 617.524.1418; e-mail arnoldia@arnarb.harvard.edu Arnold Arboretum members receive a subscrip- tion to Arnoldia as a membership benefit. To become a member or receive more information, please call Wendy Krauss at 617.384.5766 or email wendy_krauss@harvard.edu Postmaster: Send address changes to Arnoldia Circulation Manager The Arnold Arboretum 125 Arborway Boston, MA 02130-3500 Nancy Rose, Editor Andy Winther, Designer Editorial Committee Phyllis Andersen Peter Del Tredici Michael S. Dosmann William (Ned) Friedman Kanchi N. Gandhi Copyright © 2014. The President and Fellows of Harvard College TK ARNOLD ARBORETUM of HARVARD UNIVERSITY 2 Seeing the Lianas in the Trees: Woody Vines of the Temperate Zone Stacey A. Leicht-Young 13 The Pawpaw, a Forgotten North American Fruit Tree Jose I. Hormaza 24 Biodiversity Hotspot: China's Hengduan Mountains David E. Boufford 36 A Shady Character: Platanus x acerifolia Nancy Rose Front cover : Flowers of a Kentucky wisteria cultivar ( Wisteria frutescens var. macrostachya 'Blue Moon'). Photo by Nancy Rose. Inside front cover: Gentiana dolichocalyx is one of 117 Gentiana species in China's Hengduan region. This specimen was growing in Zoige Marsh, southwest of the city of Ruoergai — the marshes in this area are among the most extensive in the world and contain many rare plants. Photo by David E. Boufford. Inside back cover : This centenarian London planetree (Platanus x acerifolia, accession 16595-B) provides sum- mer shade at the Arboretum. Photo by Nancy Rose. Back cover : A Stellera chamaejasme blooms in an alpine meadow in the Hengduan region. This species exhibits several strikingly distinct color forms, usually with one color restricted to a single geographic area. Photo by David E. Boufford. Correction to "Untangling the Twisted Tale of Oriental Bittersweet" by Peter Del Tredici, Arnoldia Volume 71, Issue 3: On page 9, the image captioned "Portrait of Thomas Hogg, Jr." is instead a portrait of his father, Thomas Hogg, Sr. At right is a photograph of Thomas Hogg, Jr. (circa 1887), courtesy of the LuEsther T. Mertz Library of the New York Botanical Garden. STACEY A. LE1CHT- YOUNG Seeing the Lianas in the Trees: Woody Vines of the Temperate Zone Stacey A. Leicht-Young Without a support structure to climb, this American wisteria ( Wisteria frutescens, accession 1414-85) stretches laterally and spills over a rock wall in the Arboretum's Leventritt Shrub and Vine Garden. ■ VT v tsi ..w ■Tf VnH * f : JT! . T 1 't'flrtt l i r ^ vf. i ■ .1 \ WfimKtx 'M _ *\Tni ■■ ■ : \ 1 JL v igfj ; I n the forests and edge habitats of temperate North America, there is a group of woody plants that is well recognized but often over- looked by both the casual observer and scien- tific researcher alike. These woody plants are generally described as "vines," hut are more accurately called lianas. The ability of lianas to grow and climb in all directions, not just taller and wider like the better-known trees and shrubs, makes them a unique group of plants worthy of further study and appreciation. What is a Liana? In the simplest sense, lianas are woody vines. The term liana is better known from tropical climates where they are more abundant. By def- STACEY A. LEICHT- YOUNG Lianas 3 Virginia creeper ( Parthenocissus quinquefolia ), a common North American liana, climbing up a tree trunk. inition lianas (and herbaceous vines) are plants unable to support themselves; to grow upwards, they require other plants or structures to sup- port them. The advantage to using other plants for support is that lianas can invest resources into growing a large leaf area for photosynthe- sis without investing much into stem materi- als. A disadvantage is that when the support a liana is growing on falls down, it will also fall. However, because of their unique stem anat- omy and elastic growth, they can most often resprout from their stems or roots, or simply grow along the ground until they encounter a new support. This flexibile growth habit is per- haps the defining element of lianas. The liana growth form is found in many different plant families, indicating that the climbing habit has evolved several different times. The result is a great diversity of liana species that grow world- wide in varied habitats. Lianas of the North Temperate Zone The highest diversity of liana species is in tropical areas where they can make up 25% or more of the total plant species in some forests. Lianas are much less prevalent in temperate North America, though; one estimate from North and South Carolina indicated that lia- nas constituted just 1.3% of the native plant species (Gentry 1991). Europe has even fewer native lianas than North America. However, southern temperate areas, such as southern South America and Eastern Asia have a higher diversity of species because of differing climate and different evolutionary history. For exam- ple, the genus Celastrus has only one native representative from North America (American bittersweet, Celastrus scandens) while China has at least 25 species Celastrus angulatus is a bittersweet species from China with large leaves. NANCY ROSE STACEY A. LEICHT- YOUNG JOSEPH LAFOREST, UNIVERSITY OF GEORCIA, BUGWOOD.ORG MANY WAYS TO CLIMB A TREE One of the most fascinating aspects of lianas (and herbaceous vines) is the many different methods by which they can climb trees, trellises, and even walls or rockfaces. In fact, Charles Darwin was one of the first to publish on the many different mechanisms that vines use to climb objects (Darwin 1867). Although there is some variation in how these groupings are made, the general categories are root climbers, adhesive tendrils, tendrils, stem twiners, and petiole climbers. Root Climbers Root climbing lianas use adhesive adventitious roots to climb trees or rock faces. These roots can often look like bunches of hairs along the liana stems. These species grow close to the substrate they are attached to and sometimes form lateral branches that grow out and away from the mam stem of the liana. Familiar temperate root climbing species include poison ivy ( Toxicodendron radicans), trumpet creeper ( Campsis radicans), climbing hydrangea (Hydran- gea anomala ssp. petiolaris ), woodvamp (Decumaria bar- bara), and the evergreens English ivy ( Hedera helix) and wintercreeper ( Euony - mus fortunei). (Far left) Hairlike aerial roots of poison ivy attach the vine to the tree. (Left) The shiny, light green foliage of woodvamp (. Decumaria barbara ), a root- climbing species native to the southeastern United States. Adhesive Tendrils Like root climbers, lianas that have adhesive tendrils adhere to the tree or surface that they are climb- ing. However, it is not the roots that are doing the climbing in this case, but modified tendrils that have small adhesive pads at the tips. Adhesive tendril climbing lianas include Virginia creeper ( Parthe - nocissus quinquefolia ), which is one of the most common lianas in the forests of the Eastern United States,- its relative, Boston or Japanese ivy (P. tricuspidata)-, and the showy-flowered crossvine ( Bignonia capreolata ), a species native to the southeastern and south central United States. (Left to right) Tendrils tipped with adhesive discs cling directly to supports; flowers of a crossvine cultivar ( Bignonia capreolata 'Tangerine Beauty'); the unique leaves and adhesive tendrils of a wild crossvine climbing a white pine ( Pinus strobus ). NANCY ROSE Tendrils Tendrils are structures that are formed through modifications of the stem, leaves, leaf tips, or stipules (outgrowths at the base of a leaf). Ten- drils coil around small objects such as twigs, allowing the liana to climb. The most familiar temperate lianas that use tendrils are grapes [Vitis spp.) and porcelainberry ( Ampelopsis brevipedunculata), another member of the grape family (Vitaceae). Greenbrier (Smilax rotundifolia ) and other Smilax species use tendrils that are actually modified thorns to climb. Although members of the genus Smilax do not technically form woody stems (they are monocots, like lilies), they are often considered to be lianas because their stems persist overwinter and form leaves in the spring. (J Z D O >p (-* E U < >* UJ U (Left) Grape tendril. (Above) Crimson glory vine ( Vitis coigne- tiae ) is grown as an ornamental for its red to purple fall foliage. Stem Twiners Stem twining lianas, as the name describes, use their stems to climb up objects by twining around them. They can also form somewhat self- supporting columns when many stems entwine. Stem twiners include bit- tersweets ( Celastrus spp.) , vine honeysuckles ( Lonicera spp.), wisterias (Wisteria spp.), chocolate vine ( Akebia quinata ), and supple-jack ( Berchemia scandens ), a lesser known native liana from the southeastern United States. Another species, the aromatic Chinese magnolia vine (Schisandra chinensis ), is a stem twiner from one of the more ancient groups of flowering plants. Twining vines wrap around supports or even their own stems to climb. At left, entwined Oriental bittersweet ( Celastrus orbiculatus ) and Dutch- man's pipe ( Aristolochia macrophylla). Twining climbers include vining honeysuckles such as Lonicera x heckrottii 'Goldflame' (far left). Petiole Climbers Petiole climber lianas use their petioles (the small stalks at the base of leaves) to twine around objects in a manner similar to the ten- dril climbers. In temperate regions, clematis ( Clematis spp.) is the most prominent peti- ole climber. There are hundreds of Clematis taxa including showy large-flowered hybrids as well as small-flowered species such as the white-flowered C. virginiana, C. terniflora, and C. vitalba that bloom in late summer or early fall. (Right) Twining petiole of Clematis virginiana. (Far right) Sweet autumn clematis (C. terniflora ) is an Asian species that can escape cultivation and closely resembles the native virgin's bower (C. virginiana ). STACEY A. LEICHT-YOUNG NANCY ROSE STACEY A. LEICHT- YOUNG 6 Arnoldia 72/1 • July 2014 Fox grape ( Vitis labrusca), here showing characteristic matted white hairs on the underside of its leaves, is native to the eastern United States and is a par- ent species of the cultivated Concord grape. The main reason cited for the lower diversity and numbers of lianas in the temperate zone is the presence of wide vessels in their stems. Vessels are part of plants' xylem tissue, which transports water from the roots to the leaves. In plants such as trees and shrubs, which are self- supporting, the wood structure is denser and has narrower vessels to provide structural support. Since lianas can have very long, flexible stems (because they use other plants for support), they have both very wide and very long vessels to move sufficient amounts of water to their large leaf canopy. However, there is a disadvantage to wide vessels. Large vessels, coupled with thin stems that do not provide much insulation, are more susceptible to the formation of air bubbles within them when temperatures drop below freezing. These bubbles are known as "freezing- induced embolisms." The embolism will block the flow of water through the liana stem, and potentially destroy the vessel if the air bubble is not dissolved back into the liquid when temperatures warm. If enough vessels are blocked, the liana cannot survive (Schnitzer 2005). Temperate lianas do have adapta- tions to offset embolism. Some spe- cies, such as grapes (Vitis spp.), are able to use positive root pressure to push air bubbles out of vessels in early spring; this is why grape stems "bleed" when cut in the early spring. Other species, such as Orien- tal bittersweet ( Celastrus orbicula- tus), grow new xylem to replace any that was damaged by freezing in the spring (Tibbetts and Ewers 2000). In the far northern parts of its range in the United States and Canada, poi- son ivy ( Toxicodendron radicans ) grows as a low, trailing vine, not as the large, more exposed lianas seen in the Midwest and eastern United States (Schnitzer 2005). From a study of lianas in Chile, which has a southern temperate climate that experiences fewer continuous freez- ing days compared to northern tem- perate climates, lianas were found to have a mixture of large and small vessels, allowing transport of water in the small vessels even if the large ones became embolized (Jimenez- Castillo and Lusk 2013). Although the tem- perate zone has a lower diversity of lianas as a result of their susceptibility to embolisms, there are many liana species that do thrive in these habitats and contribute to forest dynamics. The Ecology of Climbing Type A liana's climbing method can provide infor- mation about the ecology of the species in natural settings (Carter and Teramura 1988). Root climbing and adhesive tendril climbing lianas can attach to supports of any size since they adhere to the surfaces they are climbing on. Often these species will grow in darker forest understories since they attach to larger trees that produce more shade. These species can also he seen growing up rock faces, and on Lianas 7 : 5 5 ; j j c j ; c n stone walls in gardens. Tendril climbers, stem twiners, and petiole climbers all need smaller supports to climb on since the stems or ten- drils can only wrap around smaller diameter objects such as twigs. These species are most commonly observed in open forested habitats or along forest edges where there are small supports (e.g., shrubs and small trees) and higher light availability. However, some of these species — most notably grapes and Oriental bittersweet — can employ other methods to reach the canopy in older forests with larger trees. Grapes often attach to trees when they are younger and con- tinue to grow with them as the trees get taller, spreading across the canopy by means of their tendrils. This is why on a walk in the woods one can see very large grape stems scaling a tree straight from the forest floor to the canopy. Oriental bittersweet, on the other hand, can climb other lianas such as grapes to reach the canopy (this is called "laddering"), or it can "sit and wait" in the forest understory, grow- ing along the ground until a gap forms from a tree fall, resulting in higher light and smaller diameter trees growing in the gap that it can climb (Leicht and Silander 2006). So, although Grape [Vitis sp., far left) climb- ing on American beech ( Fagus gran- difolia) in mature forest. Oriental bittersweet (light bark) using grape (dark bark) as a ladder to reach the canopy. lianas are more abundant in high light, dis- turbed habitats because of the higher availabil- ity of small supports to climb on, they can be present in old-growth forests as well (Leicht- Young et al. 2010). North American Lianas and Their Asian Relatives The liana floras of North America and East Asia have many genera in common. For exam- ple, Wisteria, Clematis, Celastrus, Vitis, and Lonicera all have Asian and North American species, but Asia has greater species diversity. Since North America and East Asia share simi- lar latitudes, many liana species (and tree, shrub, and herbaceous species as well) were brought STACEY A. LEICHT- YOUNG ROBIN BARANOWSKI 8 Arnoldia 72/1 • July 2014 Japanese honeysuckle (left, Lonciera japonica ), an invasive honeysuckle from East Asia, and trumpet honeysuckle (right, L. sempervirens ), a native North American species. from East Asia to North America for both prac- tical (erosion control, wildlife forage) and hor- ticultural (beautifying the landscape) purposes, mostly within the last 150 years. Many of these plant species have not spread because they are unable to move across the landscape via seed, were not planted in high numbers across a large area, or were constrained by climatic conditions (e.g., cold winter temperatures). But others have escaped from their original planting locations and become naturalized and sometimes inva- sive in the novel environment. The very attributes of these Asian species that make them desirable horticultural species (e.g., drought tolerance, rapid growth, abundant flower or fruit production) in many cases "pre- adapt" them for naturalizing in the landscape in adverse conditions. Indeed out of the 12 liana species from East Asia that are listed on state invasive species lists, 1 1 were introduced for ornamental purposes while lcudzu ( Pueraria montana var. lob at a) was planted extensively for erosion control (Leicht- Young and Pavlovic 2014). In addition, when plants are brought into a new geographic area they often escape from the herbivores and pathogens that kept them in check in their home range, thus allowing them to grow more prolifically in their new location where they lack these competitors. Invasive lianas are those species that have propagated beyond self-contained naturalized populations (such as through birds dispersing their seeds), and that have been observed to have negative effects on native ecosystems because of their high densities. These lianas have the attributes of other invasive plants, and because most lia- nas, native or non-native, can grow rapidly up and over objects, invasive lianas can be said to have a "perfect storm" of characteristics, and can cause widespread damage to native eco- systems. This damage includes outcompetmg native vegetation, adding weight to tree cano- pies and increasing the probability of breakage or fall during wind or ice storms, and girdling trees by wrapping around the trunks and stop- ping the flow of water and nutrients to the tree. Some of the more damaging invasive liana spe- cies in the northeastern United States are Ori- ental bittersweet, Japanese honeysuckle, and porcelainberry. While some native lianas can also damage trees and vegetation, the high con- centrations of invasive lianas in a given loca- tion can accelerate this process. These invasive lianas are very challenging for natural areas managers to combat because they can resprout from their roots after they have been cut or treated with herbicide, and bird-dispersed fruits that move over long dis- STACEY A. LEICHT- YOUNG STACEY A. LEICHT- YOUNG Damage to tree trunk from Oriental bittersweet. Porcelainberry ( Ampelopsis brevipedunculata ), originally cultivated for its attractive multi-hued fruit, has escaped cultivation through bird dis- persal of seeds and is now highly invasive in edge habitats throughout much of the Northeast and Mid-Atlantic regions. Japanese hydrangea vine cultivars ( Schizophragma hydrangeoides 'Roseum [left] and 'Moonlight' [right]) cling to rock walls in the Leventritt Shrub and Vine Garden. STACEY A. LEICHT- YOUNG ROBIN BARANOWSKi 10 Arnoldia 72/1 • July 2014 tances can reintroduce the plant to a treated area. Fortunately, due to both research and out- reach efforts, the public as well as those work- ing in the horticultural field are more aware of the negative attributes of these and other inva- sive plants, and they are rarely encouraged for plantings. It is important to note that although there are Asian species that have escaped from cultivation and become invasive, other species, such as climbing hydrangea ( Hydrangea ano- mala ssp. petiolaris), Japanese hydrangea vine ( Schizophragma hydrangeoides ), and Chinese magnolia vine ( Schisandra chinensis ) have not been observed to escape garden settings. Changes on the Way? Non-native invasive lianas have changed the face of our native ecosystems by altering the makeup of species present in the environment and often competing with native species for resources and space. With global changes such as increasing temperatures and carbon dioxide (C0 2 ) levels along with increasing landscape fragmentation (e.g., hurricane damage [Allen et al. 2005]), the role that all lianas will play in these future ecosystems may become more prominent. Evidence suggests that with increasing C0 2 lianas will grow more abundantly. Another interesting (but disturbing) change with increasing C0 2 is that poison ivy may contain more urushiol, the compound that causes the allergic reaction (Zislca et al. 2007). In tropical areas, there has been a documented increase in lianas that has been attributed to increasing C0 2 as well as increasing forest fragmentation (Schnitzer and Bongers 2011). This concept has been little explored in the temperate zone, hut it could be expected that similar changes will be seen here as the risk of freezing-induced embo- lisms and severe frost damage from cold tem- peratures decreases with warming (such as the predicted expansion of kudzu into the northern United States). In addition, the prominence of secondary forests has increased, especially in regions like New England where young forests have grown up from abandoned agricultural land on the edges of developed areas. These disturbed secondary forests are ideal for liana Kudzu ( Pueraria montana var. lobata) clambers up a sign post in Maryland. growth because of high light conditions and the presence of small diameter supports. Thus, the combination of warmer temperatures, increas- ing C0 2/ and habitat fragmentation may result in ideal conditions for an increase in the abun- dance and growth of temperate lianas. Surprisingly little is known about the role lianas currently play in the ecology of temper- JIL SWEARINGEN, USDI NATIONAL PARK SERVICE, BUGWOOD.ORG NANCY ROSE Lianas 1 1 A tangle of wild grape (Vitis riparia ) and Oriental bittersweet climbs trees in the Arboretum's Bussey Brook Meadow. ate forests. We know from tropical studies and a handful of temperate studies that lianas com- pete with trees, not just in the obvious com- petition for light above ground, but also in the commonly overlooked root zone. In temperate species, researchers have found trees compet- ing with liana roots show slower growth rates than those just competing above ground (Dil- lenburg et al. 1993). In addition, in seasonally dry tropical forests liana roots are able to tap deep water sources over a wide area, which allows them to continue to grow during drought while trees and shrubs often go dormant (Schnitzer 2005). From what we know about species like Oriental bittersweet, they can form exten- sive root networks that can com- pete with neighboring species and contribute to vegetative spread. Thus, roots likely contribute an important part in how lianas are able to successfully colonize and persist in competition with other plant species. Intense competition from lia- nas above and below ground in high light situations, such as gaps in forests, may result in “liana tangles." These liana tangles can suppress the ability of trees to regrow into a forest gap or slow the succession of old fields to for- ests for many years. In temperate areas where the growing season is restricted to the warmer months, regrowth of trees and other spe- cies may be slowed for even lon- ger. Additionally, as lianas grow up trees they put additional stress on them, resulting in a higher chance of tree fall. This cycle of lianas increasing the chance of tree fall and resprouting in newly formed gaps may have an impor- tant influence on the regrowth of subsequent secondary forests, especially after high-wind events or ice storms. These concepts have been studied to some extent in the tropics but need further observation and research in temperate habi- tats to increase understanding of how lianas contribute to the composition, structure, and ecosystem dynamics of temperate forests and what their future contribution may be in light of global climate change. 12 Arnoldia 72/1 • July 2014 The next time you enjoy cascades of vio- let wisteria flowers on a pergola in the spring or see scarlet-leafed Virginia creeper on an autumn walk through the woods, consider the unique adaptations for growth that these and other lianas have made. By closely observing the fascinating species of temperate lianas that we often encounter we can better appreciate them and reflect on their important place in our ecosystem. Literature Cited Allen, B. P., R. R. Sharitz, P. C. Goebel. 2005. Twelve years post-hurricane liana dynamics in an old-growth southeastern floodplain forest. Forest Ecology and Management 218: 259-269. Carter, G. A. and A. H. Teramura. 1988. Vine photosynthesis and relationships to climbing mechanics in a forest understory. American Journal of Botany 75: 1011-1018. Darwin, C. 1867. On the movements and habits of climbing plants. Journal of the Linnean Society of London Botany 9: 1-118. Dillenburg, L. R., D. R Whigham, A. H. Teramura, and I. N. Forseth. 1993. Effects of below- and above- ground competition from the vines Lonicera japonica and Parthenocissus quinquefolia on the growth of the tree host Liquidambar styraciflua. Oecologia 93:48-54. Gentry, A. H. 1991. The distribution and evolution of climbing plants. In F. E. Putz and H. A. Mooney (eds.) The Biology of Vines. Cambridge: Cambridge University Press. Pp. 3-52. Jimenez-Castillo, M. and C. H. Lusk. 2013. Vascular performance of woody plants in a temperate rain forest: lianas suffer higher levels of freeze-thaw embolism than associated trees. Functional Ecology 27: 403-412. Virginia creeper ( Parthenocissus quinquefolia ) in fall color. Schnitzer, S. A. 2005. A mechanistic explanation for global patterns of liana abundance and distribution. The American Naturalist 166: 262-276. Schnitzer, S. A. and F. Bongers. 2011. Increasing liana abundance and biomass in tropical forests: emerging patterns and putative mechanisms. Ecology Letters 14: 397M06. Leicht, S. A. and J. A. Silander. 2006. Differential responses of invasive Celastrus orbiculatus (Celastraceae) and native C. scandens to changes in light quality. American Journal of Botany 93: 972-977. Leicht-Young, S. A., N. B. Pavlovic, K. J. Frohnapple, and R. Grundel. 2010. Liana habitat and host preferences in northern temperate forests. Forest Ecology and Management 260: 1467-1477. Leicht-Young, S. A. and N. B. Pavlovic. 2014. Lianas as invasive species in North America. In S. A. Schnitzer, F. Bongers, R. J. Burnham, and F. E. Putz (eds.) The Ecology of Lianas. In press. Tibbetts, T. J. and F. W. Ewers. 2000. Root pressure and specific conductivity in temperate lianas: Exotic Celastrus orbiculatus (Celastraceae) vs. native Vitis riparia (Vitaceae). American Journal of Botany 87: 1272-1278. Ziska, L., R. Sicher, K. George, and J. Mohan. 2007. Rising atmospheric carbon dioxide and potential impacts on the growth and toxicity of poison ivy ( Toxicodendron radicans ). Weed Science 55: 288-292. Stacey Leicht-Young is a Putnam Fellow at the Arnold Arboretum. NANCY ROSE The Pawpaw, a Forgotten North American Fruit Tree Jose I. Hormaza T he number of fruit trees native to North America is low compared to the many cultivated fruit species of Eurasian ori- gin that currently form the basis for most fruit production in the New World. But there are a number of North American species with commercial possibilities, although many are neglected. Examples include a range of berries such as lowbush and highbush blueberries ( Vaccinium angustifolium and V. corymbo- sum ), cranberries (V. macrocarpon ), huckle- berries (V. membranaceum ), American persim- mon [Diospyros virginiana), American plum ( Prunus americana), pawpaw ( Asimina triloba), red mulberry ( Morus rubra), and juneberries ( Amelanchier spp.), most of them only avail- able at a very small scale in some local markets. Among them, the pawpaw is probably one of the most interesting of the native North Ameri- can fruit trees because of its exotic-tasting fruit and easy cultivation. The History of Pawpaw The earliest written report of pawpaw was made in 1541 by a Portuguese officer who was a member of Spaniard Hernando de Soto's expe- dition through the southeastern United States. He noted Native Americans growing and eat- ing pawpaws in the Mississippi Valley region (Pickering 1879; Sargent 1890): "There is a fruit through all the country which groweth on a plant like Ligoacan [possibly a reference to lig- num vitae, Guaiacum officinale ], which the Indians do plant. The fruit is like unto Peares Riall ["pears royal"]; it has a very good smell, and an excellent taste" (Hackluyt 1609). Appar- ently, the name pawpaw was given to the tree by the members of the de Soto expedition for the resemblance of the fruits to the tropical fruit papaya ( Carica papaya) that they already knew (Sargent 1890), papaya being a Spanish word derived from the Taino word papaia. In some English speaking countries, such as Aus- tralia and New Zealand, the tropical papaya is also known as pawpaw, often resulting in con- fusion between the two species. After this first report, pawpaw was described in records from additional explorations of the United States. One quote about the pawpaw in the northern United States is found in the so-called de Cannes memoir of 1690 (Pease and Werner 1934), probably written by Pierre Deliette, a French trader and colonial official who lived for several decades in Illinois: "There were other trees as thick as one's leg, which bend under a yellowish fruit of the shape and size of a medium-sized cucumber, which the The name “pawpaw" was apparently derived front papaya ( Carica papaya ), seen here, a tropical fruit that has a slight resemblance to pawpaw fruit. FOREST AND KIM STARR, STARR ENVIRONMENTAL, BUGWOOD.ORG iiiil Pawpaw 15 savages call assemina. The French have given it an impertinent name. There are people who would not like it, but I find it very good. They have five or six nuclei [seeds] inside which are as big as marsh beans, and of about the same shape. I ate, one day, sixty of them, big and lit- tle. This fruit does not ripen till October, like the medlars." In 1709, John Lawson, a British explorer, reported in his book A New Voyage to Carolina — probably the first report of paw- paw in English — that "The Papau is not a large tree. I think I never saw one a foot through; but has the broadest leaf of any tree in the Woods, and bears an apple about the bigness of a hen's egg, yellow, soft, and as sweet as anything can well be. They [the Indians] make rare puddings of this fruit" (Lawson 1709). English natural- ist Mark Catesby described and illustrated the pawpaw in his classic 1754 edition of The Natural History of Carolina, Florida, and the Bahama Islands: "The trunks of these trees are seldom bigger than the small of a man's Leg, and are about ten or twelve feet high, having a smooth greenish brown Bark. In March when the leaves begin to sprout, its blossoms appear, consisting each of six greenish white petals, the fruit grows in clusters of three, and some- times four together,- they are at first green, and when ripe yellow, covered with a thin smooth skin, which contains a yellow pulp, of a sweet luscious taste; in the middle of which lye in two rows, twelve seeds divided by so many thin membranes. All parts of the tree have a rank, if not a foetid smell" (Catesby 1754). In 1749, the Jesuit priest Joseph de Bonnecamps described the pawpaw: "Now that I am on the subject of trees, I will tell you something of the assimine- tree, and of that which is called the lentil-tree. The 1st is a shrub, the fruit of which is oval in shape, and a little larger than a bustard's egg; its substance is white and spongy, and becomes yellow when the fruit is ripe. It contains two or three kernels, large and flat like the garden bean. They have each their special cell. The fruits grow ordinarily in pairs, and are suspended on the same stalk. The French have given it a name which is not very refined, Testiculi asini. This is a delicate morsel for the savages and the Canadians; as for me, I have found it of an unendurable insipidity" (Thwaites 1899). Besides these early reports, it is known that George Washington planted pawpaws at this home, Mount Vernon, in Virginia (Washing- ton 1785). Pawpaws were also among the many plants that Thomas Jefferson cultivated at Mon- ticello, his home in Virginia (Betts et al. 1986); during his time as Minister to France he had pawpaw seeds (Jefferson 1786) and plants (Jef- ferson 1787) shipped to his friends in Europe. In September 1806, the members of the Lewis and Clark expedition subsisted almost entirely on wild pawpaws for several days. William Clark wrote in his journal : "Our party entirely out of provisions. Subsisting on poppaws. We divide the buiskit which amount to nearly one buisket per man, this in addition to the poppaws is to last us down to the Settlement's which is 150 miles. The party appear perfectly contented and tell us that they can live very well on the pap- paws" (Lewis and Clark 1806). Daniel Boone and Mark Twain were also reported to have been pawpaw fans (Pomper and Layne 2005), and early settlers also depended partially on pawpaw fruits to sustain them in times of crop failure (Peterson 1991). Pawpaws are well estab- lished in American folklore and history (the tra- ditional American children's song, "Way down yonder in the pawpaw patch," is still popular) and several towns, creeks, and rivers have been named after this fruit tree. Taxonomy, Origin, and Dissemination The first fossils of Asimina have been dated to the Eocene (about 56 to 34 million years ago) and the first clearly resembling A. triloba to the Miocene (about 23 to 5.3 million years ago) (Berry 1916). Janzen and Martin (1982) hypothe- sized that large fruits produced by some Central American plant species were dispersed by large mammals that were extinct by the end of the Pleistocene,- they extrapolated this observation to North American plants that produce large fruits, such as the pawpaw. With the extinc- tion of the fruit-eating megafauna, the range Naturalist Mark Catesby used flower and fruit specimens preserved in alcohol to create his illustration of pawpaw, which may explain the lack of maroon flower coloration in this depiction. Image courtesy Missouri Botanical Garden, www.botanicus.org 16 Arnoldia 72/1 • July 2014 Silva of North America Tab. XV. ASIMINA TRILOBA, Dunal. A Purer rurr direr / 'vf. .P . Tantar. Paris Charles Edward Faxon's illustrations of Asimina triloba from Charles Sprague Sargent's Silva of North America, 1890. Pawpaw 17 Silva of North America. Tab. XVI . 18 Arnoldia 72/1 • July 2014 of the plant species dispersed by those animals started narrowing. Pawpaw probably survived thanks to its ability to easily reproduce vegeta- tively, producing numerous root suckers that form pawpaw patches in the wild (Barlow 2000, 2001). After the last ice age, humans could have become the new main vector dispersing paw- paw seeds and probably started the selection of plants with superior characteristics (Peterson 1991). Keener and Kuhns (1997) suggested that the northernmost distribution of the pawpaw into southern Ontario and western New York, Ohio, and Michigan was attributable to Iroquois population movements. Murphy (2001), how- ever, argued against that hypothesis, suggesting instead that the spread of pawpaw could have been mainly by means of other mammals that seem to be able to eat pawpaw fruits, including raccoons, squirrels, opossums, foxes, bears, and white-tailed deer. The North American pawpaw, Asimina tri- loba (L.) Dunal, is the northernmost represen- tative of the mainly tropical and subtropical family Annonaceae, the largest living family within the order Magnoliales in the Eumag- noliid clade among the early-divergent angio- sperms (Bremer et al. 2009). Annonaceae has more than 130 genera and 2,400 species (Couv- reur et al., 2011), 900 of which are found m the Neotropics (Chatrou et al. 2004). Some of the tree species in the family such as cherimoya (. Annona cherimola), sugar apple (A. squamosa ), soursop (A. muricata), custard apple [A. reticu- lata), and atemoya (a hybrid between A. cheri- mola and A. squamosa ) produce edible fruits, some of which were already used as a food source by pre-Columbian cultures in Central and South America (Popenoe 1989). Pawpaw's scientific name has been changed repeatedly. Linnaeus first classified the paw- paw as Annona triloba in 1753. In 1763, Michel Adanson, a French naturalist, named the genus Asimina in his book Families naturelles des plantes. The name Asimina is adapted from the native Algonquian word assimin/rassimin/ racemin, via Cajun French assiminier (Cham- berlain 1902; Gray 1886; Sargent 1890). Another North American native fruit, the American per- simmon, also has the same root in its name, "min", the Algonquian word for fruit. However, The fruit of cherimoya ( Annona cherimola ). in 1803 Michaux reclassified the pawpaw as Orchidocarpum arietinum and in 1807 Per- soon reclassified it as P or celia triloba. In 1817 Dunal renamed the species Asimina triloba. Torrey and Gray later moved the species to the genus Uvaria, but it was finally returned to Asimina by Gray in 1886 (Krai 1960). The cur- rent accepted nomenclature for the pawpaw is Asimina triloba (L.) Dunal. The Asimina genus includes eight species native to North America (Krai i960; Callaway 1990; Brett and Callaway 1992), four of which [A. obovata [Willd.] Nash, A. pygmaea [W. Bar- tram] Dunal, A. reticulata Shuttlw. ex Chap- man, and A. tetramera Small) are found only in Florida, two [A. incana [W. Bartram] Exell and A. longifolia Krai) in Florida and southern Geor- gia, while A. parviflora (Michx.) Dunal reaches farther north, ranging from western Texas to North Carolina (Krai 1997). Asimina triloba is the most widespread of the eight species, indig- enous to 26 states in the eastern United States, I. I. HORMAZA Pawpaw 19 ranging from New York, and southern Michigan on the north, south to northern Florida, and west to eastern Texas, Nebraska, and Kansas (Callaway 1990). It is also present in Ontario, Canada (Fox 2012). A Description of Pawpaw The pawpaw is the only species in the Asimina genus that produces fruits of significant interest as a food source. It is, in fact, the largest edible fruit native to North America. It grows wild as a deciduous understory tree in hardwood forests with moist but well-drained and fertile soils in the eastern United States, often in large patches of the same genotype due to extensive root suckering (Krai I960; Pomper and Layne 2005), although sometimes different genotypes can be found in the same patch (Pomper et al. 2009). Pawpaw trees can reach up to 10 meters (32.8 feet) tall and typically have a pyramidal habit in sunny locations. Pawpaw can be grown successfully in USDA plant hardiness zones 5 through 8 (average annual minimum tempera- tures -20 to 20°F [-28.8 to -6.7°C]) (Krai 1960). Pawpaw flower buds are dark brown, pubescent, and occur singly on the previous year's growth (Krai 1960). The flowers are light green upon emergence, but gradually turn maroon, with a slightly fetid aroma. The mature flowers are A multitude of root suckers rise around the base of a pawpaw tree. IN THE ARNOLD ARBORETUM there are currently four Asimina triloba specimens obtained from different sources: • The oldest accession is 12708-A, grown from seeds sent by E. J. Cole of Grand Rapids, Michigan, in February 1903; records show that it was growing in its current location in 1926. • 1222-79-A was collected from the wild as a plant by Arboretum staff members Jack Alexander and Gary Roller in Missouri in December 1979. It grew in the nursery for a few years and then was planted in the collection in 1986. • 143-94-B was collected as seed in Michigan in October 1993 by Tim Boland (current director of the Polly Hill Arboretum in Mar- tha's Vineyard). The seeds were received in early 1994 and one of the seedlings was planted in its current location in 2003. • 205-91-A was collected as seed by staff members of the University of Guelph Arboretum (Ontario, Canada) in the floodplain of the Thames River in Middlesex County, Ontario. It was planted in the collection in 2003. Asimina triloba accession 1922-79-A in autumn. MICHAEL DOSMANN NANCY ROSE NANCY ROSE 20 Arnoldia 72/1 • July 2014 2 to 5 centimeters (0.8 to 2 inches) in diameter, with 3 outer petals, 3 smaller inner petals, and 3 sepals. Flowers emerge before the leaves have emerged and expanded. The flowers have a globular androecium and a gynoecium with 7 to 10 simple, uniloculate carpels (Lampton 1957). As with other spe- cies in the Annonaceae, pawpaw flowers show protogynous dichogamy, that is, the stigmas are receptive before pollen is released from the anthers, which often prevents self pollination. Most pawpaw cultivars are believed to be self- incompatible (Pomper and Layne 2008). The pawpaw fruits are botanically berries (Dirr 1990). The fruits are sweet, highly nutri- tious, have a pleasant but strong aroma, and have a unique exotic taste that resembles a combination of banana, mango, and pineapple (Pomper and Layne 2005). The pulp can be consumed both fresh and processed in differ- ent ways (ice cream, compotes, jam, pies, cus- tards). The fruit can weigh up to 500 grams ( 1 7.6 ounces), with the average fruit weighing around 150 to 200 grams (5.3 to 7.1 ounces); there can be significant fruit weight differences depend- ing on the genotype (Pomper and Layne 2005). The fruits have two rows of seeds with a total of 12 to 20 seeds that can be up to 3 centimeters (1.2 inches) long (Pomper and Layne 2008). As with other Annonaceae species and other early-derived angiosperm families, pawpaws are primarily pollinated by flies and beetles that are attracted to the decaying smell and dark red color of the pawpaw flower,- however, these pol- linators are unreliable (Faegri and van der Piji 1971) and often of limited availability resulting in low fruit yields both in wild stands and in cultivation (Pomper and Layne 2008). MEGAN MCCARTY Pawpaw 21 A female zebra swallowtail oviposits on an emerging pawpaw leaf. Butterflies, Pawpaw, and Coevolution The zebra swallowtail (Protographium marcel- lus, formerly Eury tides marcellus) is a beautiful black and white striped butterfly whose cater- pillars feed exclusively on Asimina leaves. (The damage made to the leaves is reported to be neg- ligible in pawpaw orchards [Pomper and Layne 2008]). Some compounds present in the paw- paw leaves (acetogenins, specific substances only found in species of the Annonaceae) are repellent to most insects and birds so the cat- erpillar accumulates them to avoid predation. These natural bioactive compounds present in the leaves, bark, and twigs of pawpaw and other species of the Annonaceae have shown some insecticidal and anti-tumoral properties (McLaughlin 2008). Of the seven swallowtail tribes, the Graphinii (to which the zebra swal- lowtail belongs) is one of the largest with about 150 species restricted to the tropics and sub- tropics except for two, Iphiclides podalirius and Protographium marcellus (the zebra swal- lowtail), that live in Palearctic and Nearctic regions, respectively (Haribal and Feeny 1998). The fact that both the zebra swallowtail and the pawpaw are the only members of their respec- tive groups to live in temperate North America indicates that both species have coevolved and provides a neat system to study coevolution and adaptation to cooler climates. The Current State of the Pawpaw There was an increased interest in growing paw- paw as a crop at the beginning of the twentieth century,- for example, in 1916 the American Genetic Association offered a $100 prize — $50 for the largest individual pawpaw tree and $50 for the tree — regardless of size — with the best fruit (American Genetic Association 1916). Yet in spite of its high potential through the years as a new high-value niche fruit crop, pawpaw is still only in the early stages of commercial production. The greatest current market poten- tial for pawpaw is probably in local markets and direct sales to restaurants and other gour- met niche customers. Most pawpaw fruits are Illustration of the exterior and interior of a pawpaw fruit painted by Royal Charles Steadman in 1924. From the USDA Pomological Watercolor Collection in the Rare and Special Collections of the National Agricul- tural Library in Beltsville, Maryland. 22 Arnoldia 72/1 • July 2014 still collected from wild stands or produced in small family orchards. Current pawpaw produc- tion challenges have been reviewed by Pomper and Layne (2005) and include the need for new high-quality cultivars, pollination improve- ment, and postharvest issues; the shelf life of a tree-ripened fruit stored at room temperature is just 2 to 3 days, although under appropriate refrigeration conditions fruits harvested before fully ripening can be held up to 3 weeks while maintaining good eating quality. A number of high-quality pawpaw cultivars with large fruit (over 5 ounces) and heavy production have been selected since 1950 at Kentucky State University, which serves as a USDA National Clonal Germplasm Repository for Asimina species (Willson and Schmeske 1980; Pomper and Layne 2005). Though pawpaws may never be as popular as apples or oranges, perhaps one day they'll at least make it out of the pawpaw patch and into the local grocery store. If you don't want to wait for that to occur, consider planting some pawpaw trees in your own backyard. This will give you the opportunity to taste an exotic fruit native to North America and, at the same time, perhaps enjoy the visit of zebra swallowtails. References American Genetic Association. 1916. Where are the best papaws? Journal of Heredity 7: 291-296. Barlow, C. 2000. The Ghosts Of Evolution: Nonsensical Fruit, Missing Partners, and Other Ecological Anachronisms. New York: Basic Books. Barlow, C. 2001. Anachronistic fruits and the ghosts who haunt them. Arnoldia 61: 14-21. Berry, E. W. 1916. The lower eocene floras of southeastern North America. United States Geological Survey, Professional Paper 91, p. 90. Betts, E. M., El. B. Perkins, and P. J. Hatch. 1986. Thomas Jefferson’s Flower Garden at Monticello, 3rd edition. Charlottesville: University Press of Virginia. Bremer, B., K. Bremer, M. W. Chase, M. F. Fay, J. L. Reveal, D. E. Soltis, P. S. Soltis, and P. F. Stevens. 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III. Botanical fournal of the Linnaean Society 161: 105-121. Brett, M. and D. J. Callaway. 1992. Our native pawpaw: the next new commercial fruit? Arnoldia 52(3): 21-29. Callaway, M. B. 1990. The pawpaw ( Asimina triloba). Kentucky State University Publications CRS- HORT1-901T. Catesby, M. 1754. The Natural History of Carolina, Florida and the Bahama Islands. London. Chamberlain, A. F. 1902. Algonquian words in American English, fournal of American Folklore 15: 240-267. Chatrou, L. W., H. Rainer, and P. J. M. Mass. 2004. Annonaceae. In: D. W. Stevenson, S. V. Heald, N. Smith, S. A. Mori, A. Henderson (eds. ). Flowering Plants of the Neotropics. Princeton, New Jersey: Princeton University Press. pp. 18-20 Couvreur, T. L. P., M. D. Pirie, L. W. Chatrou, R. M. K. Saunders, Y. C. F. Su, J. E. Richardson, and R. H. J. Erkens. 2011. Early evolutionary history of the flowering plant family Annonaceae: steady diversification and boreotropical geodispersal. fournal of Biogeography 38: 664-680. Dirr, M. A. 1990. Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture, Propagation, and Uses. 4th ed. Champaign, Illinois: Stipes Publishing. Faegri, K. and L. van der Piji. 1971. The Principles of Pollination Ecology. New York: Pergammon Press. Fox, S. 2012. Picking up the pawpaws: the rare woody plants of Ontario program at the University of Guelph Arboretum. Arnoldia 69(3): 2-13. Gray, A. 1886. The genus Asimina. Botanical Gazette 11: 161-164 Hackluyt, R. 1609. A narrative of the expedition of Hernando de Soto into Florida. By a Gentleman of Elvas. Published at Evora 1557. Translated from the Portuguese by Richard Hackluyt. London, http://archive.org/ details/anarrativeofthee34997gut (accessed January 9th 2014). Haribal, M. and P. Feeny. 1998. Oviposition stimulant for the zebra swallowtail butterfly, Eurytides marcellus, from the foliage of pawpaw, Asimina triloba. Chemoecology 8: 99-110. Janzen, D. H. and P. S. Martin. 1982. Neotropical anachronisms: The fruits the gomphotheres ate. Science 215: 19-27. Pawpaw 23 Jefferson, T. 1786. From Thomas Jefferson to John Bartram, with Enclosure, 27 January 1786, Founders Online, National Archives (littp://f ounders.archives.gov/documents/ Jefferson/01-09-02-0201, ver. 2013-08-02). Source: The Papers of Thomas Jefferson, vol. 9, 1 November 1785-22 June 1786, ed. Julian P. Boyd. Princeton: Princeton University Press, 1954, pp. 228-230. Jefferson, T. 1787. From Thomas Jefferson to John Banister, Jr., witlr enclosure, 7 February 1787," Founders Online, National Archives (http://founders.archives.gov/documents/ Jefferson/01-1 1-02-0122, ver. 2013-08-02). Source: The Papers of Thomas Jefferson, vol. 11,1 January-6 August 1787, ed. Julian P. Boyd. Princeton: Princeton University Press, 1955, pp. 121-122. Keener, C. and E. Kuhns. 1997. The impact of Iroquoian populations on the northern distribution of pawpaws in the Northeast. North American Archaeologist 18: 327-342. Krai, R. 1960. A revision of Asimina and Deeringothamnus (Annonaceae). Brittonia 12: 233-278. Krai, R. 1997. Annonaceae. In: Flora of North America. Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 16+ vols. New York and Oxford. Vol. 3, pp. 1 1-20. Lampton, R. K. 1957. Floral morphology in Asimina triloba Dunal, development of ovule and embryo sac. Bulletin of the Torrey Botanical Club 84: 151-156. Lawson, J. 1709. A New Voyage to Carolina. London. http://docsouth.unc.edu/nc/lawson/lawson. html (accessed January 9th 2014). Lewis, M. and W. Clark. 1806. September 18, 1806, entry in The Journals of the Lewis and Clark Expedition, ed. Gary Moulton. University of Nebraska Press. 2005. http://lewisandclarkjournals.unl.edu/ read/ ?_xmlsrc=l 806-09- 1 8 St_xslsrc=LCstyles. xsl (accessed January 9th 2014). McLaughlin, J. L. 2008. Paw Paw and cancer: annonaceous acetogenins from discovery to commercial products. Journal of Natural Products 71: 1311-1321. Murphy, J. L. 2001. Pawpaws, persimmons, and 'possums: on the natural distribution of pawpaws in the northeast. North American Archaeologist 22: 93-115. Pease, T. C. and R. C. Werner. 1934. The French Foundations, 1680-1693. Illinois Historical Collections, XXIII. Springfield: Trustees of the Illinois State Historical Library. https://archive.org/details/frenchfoundation23peas (accessed January 9th 2014). Peterson, R. N. 1991. Pawpaw (Asimina). Acta Horticulturae 290: 569-602. Pickering, C. 1879. Chronological History of Plants. Vol. 1. Boston: Little, Brown and Company. Pomper, K. W. and D. R. Layne. 2005. The North American pawpaw: botany and horticulture. Horticultural Reviews 31: 351-384. Pomper, K. W. and D. R. Layne. 2008. Asimina triloba, pawpaw. In: J. faniclc and R. E. Pauli (eds.). The Encyclopedia of Fruits and Nuts. CAB International, pp. 62-68. Pomper, K. W., J. D. Lowe, L. Lu, S. B. Crabtree, and L. A. Collins. 2009. Clonality of pawpaw ( Asimina triloba ) patches in Kentucky. Journal of the Kentucky Academy of Sciences 70: 3-1 1 . Popenoe, H. 1989. Lost Crops of the Incas: Little Known Plants of the Andes with Promise of Worldwide Cultivation. Washington, D.C.: National Academy Press. Sargent, C. S. 1890. Silva of North America. New York: Houghton Mifflin. Thwaites, R. G. 1899. The Jesuit Relations and Allied Documents. Travels and explorations of the Jesuit missionaries in New France 1610-1791. Vol. LIX. Cleveland: The Burrows Brothers Publishers. Washington, G. 1785. Founders Online, National Archives (http://founders.archives.gov/ documents/Washington/0 1-04-02-0002-0003, ver. 2013-08-02). Source: The Diaries of George Washington, vol. 4, 1 September 1784-30 June 1786, ed. Donald Jackson and Dorothy Twohig. Charlottesville: University Press of Virginia. 1978. pp. 96-111. Willson, M. F. and D. W. Schmeske. 1980. Pollinator limitation, fruit production, and floral display in Pawpaw ( Asimina triloba). Bulletin of the Torrey Botanical Club 107: 401-408. Jose I. Hormaza is a Professor at the IHSM La Mayora Research Institute of the Spanish Council for Scientific Research (IHSM-CSIC-UMA) in Malaga, Spain, and a Research Associate with the Arnold Arboretum. Biodiversity Hotspot: China's Hengduan Mountains David E. Bouffoid I n southwestern China, in the southeastern corner of the Qinghai-Tibet Plateau, lies one of the world's 35 biodiversity hotspots: the Hengduan Mountains. This hotspot occurs at the juncture of mountain systems where pre- cipitation can vary tremendously due to a com- bination of topography, climate, and hydrology. The terrain forms topographic channels that funnel seasonal monsoon rains up through the river valleys from the lowland tropics of south- ern China, India, and Myanmar (Burma) to the southeastern edge of the 5,000-plus-meter-high (16,400-plus-feet) Qinghai-Tibet Plateau. The region also receives vast amounts of water from the five major rivers that drain the plateau: the Yarlung Zangbo Jiang (which becomes the Brah- maputra in India and the Jamuna in Bangla- desh); the Ayayerwaddy (Irrawaddy); Nu Jiang (Salween); Lancang Jiang (Mekong); and Jinsha Jiang (known in the West as the Yangtze, and Qinghai-Tibetan Plateau Myanmary % India .. : Yr_ ' " - * * ~ I v . Hotspot , 7 WM \ / Hengduan Hotspot 25 Sichuan, Batang Xian. A glacial lake lies at about 4,500 meters (14,764 feet) on the south side of the pass at Haizi Shan, surrounded by a Kobresia (bog sedge) meadow and with scattered dwarf Salix and Rhododendron on nearby slopes. What's a Biodiversity Hotspot? As defined by Conservation International, to qualify as a biodiversity hotspot a region must meet two strict criteria: • It must have at least 1,500 vascular plants as endemics, which is to say, it must have a high percentage of plant life found nowhere else on the planet. A hotspot, in other words, is irreplaceable. • It must have 30% or less of its original natural vegetation. In other words, it must be threatened. • Around the world, 35 areas qualify as hotspots. They represent just 2.3% of Earth's land surface, but they support more than half of the world's plant species as endem- ics — i.e., species found no place else — and nearly 43% of bird, mammal, reptile, Hi and amphibian species as endemics. (http://www.conservation.org/How/Pages/ Hotspots. aspx) ALL IMAGES BY THE AUTHOR 26 Arnoldia 72/1 • July 2014 by several different names in China: Tongtian He in Tibet, Jinsha Jiang from Qinghai through Yunnan, and Chang Jiang from the point where it enters Sicliuan from Yunnan). The Nu Jiang, Lancang Jiang, and Chang Jiang have carved deep gorges through the region, and in some places flow less than 70 kilometers (44 miles) apart. The Huang He (Yellow River), not included within the Hengduan area, flows northeast from the Qinghai-Tibet Plateau, but its source is just one mountain range north of the source of the Tongtian He/Jinsha Jiang/Chang Jiang/Yangtze. Extreme topographic relief is a characteristic feature of the Heng- duan region. Hutiaoxia (Tiger Leap- ing Gorge), the gorge of the Jinsha Jiang between Yulong Xueshan (Jade Dragon Snow Mountain) and Haba Xueshan (Haba Snow Mountain), is at an elevation of around 1,900 meters (6,234 feet). Haba Xueshan on the northwest side rises to 5,396 meters (17,703 feet) and Yulong Xue- shan on the southeast side rises to 5,596 meters (18,360 feet). The peaks of the two mountains are 21 kilome- ters (13 miles) apart. To the north and west, the hotspot is bounded by the high, dry Qinghai- Tibet Plateau. On the east, the Heng- duan region drops precipitously from over 3,000 meters (9,843 feet) to the low, flat, Sichuan basin at about 600 meters (1,969 feet). The southern boundary in Yunnan is at the 2,000 meter (6,562 feet) level of the Yun- nan plateau (Boufford and Van Dijlc 2000). The average elevation in the easternmost part of the Hengduan region is over 3,000 meters (9,843 feet) and nearly 5,000 meters (16,400 feet) in the west. The highest peaks are Gongga Shan (7,556 meters [24,790 feet]) in Sichuan and Namjag- barwa (7,782 meters [25,530 feet]) at the west- ern end of the hotspot in southeastern Xizang. (Top) Carpinus cordata, Pinus, Helwingia japonica, and Rhododendron augustinii (in bloom) on a rock outcrop on Motianling Shan, Baishui Jiang Nature Reserve in Gansu Province. (Bottom) The flowers of Rhododen- dron augustinii. VEGETATION Within the hotspot are numerous vegetation types, each with its characteristic floristic asso- ciations. On the east and southeast, the vegeta- tion comprises mixed broadleaved deciduous and evergreen forests with such characteristic plants of central China and the Sino-Japanese Floristic Region as Cercidiphyllum, Tetra- Hengduan Hotspot TJ Sichuan, Litang Xian. North of Litang between Litang and Xinlong. A broad ravine with numerous side seepages and both moist and dry upland meadows, featuring the tall, yellow-bracted floral spikes of Rheum alexandrae (a rhubarb relative) and yellow-flow- ered Pedicularis longiflora var. tubiformis in the foreground along the stream. centron, Acer (maple — 45 species!), Aesculus (buckeye), Tilia (linden), several genera within Lauraceae (the laurel family), Meliosma, Phel- lodendron (corktree), Evodia, Cornus (dog- wood), Ostryopsis, Carpinus (hornbeam), Ostrya (hophornbeam), Betula (birch), Quercus (oak), Lithocarpus, Fagus (beech), Elaeocarpus, and Ailanthus (Boufford and Ohba 1998). In formerly glaciated valleys and on higher slopes, Abies (fir), Picea (spruce), Betula and other boreal plants intermix with vegetation generally considered to be warm-temperate. Full grown, well-formed oak and fir trees reach an elevation of around 4,600 meters (15,092 feet) in some places and intermix with alpine meadows, scree slopes, and Rhododendron thickets. Herbaceous vegetation reaches to 6,000 meters (19,685 feet), although few plant specimens have been collected above 5,500 meters (18,045 feet). The east and southeast portions of the Heng- duan region are the best known, since they were easily reached by explorers and research- ers coming up the Chang Jiang (Yangtze) or entering from Chengdu, about 100 kilometers (62 miles) away, or from Kunming. The forests on the eastern slopes also harbor some of the last surviving populations of giant panda, and China's best known and perhaps largest panda research station at Wolong Shan. About half 28 Arnoldia 72/1 • July 2014 of the Hengduan region within Sichuan was originally forested; the other half is part of what in China is called the Chuan-Zang-Gaoyuan (Sichuan-Xizang Plateau) (Sichuan Vegetation Study Group 1980; Wu 1988). Emei Shan (Mt. Omei), well-known as a center of plant diver- sity and for its many temples, is the best known and most thoroughly documented site within the Hengduan Mountains (Li and Shi 2007). Above 3,500 meters (11,483 feet) is a rich mixture of alpine meadows, scree slopes, cliff faces, marshes surrounding glacial lakes, and other vegetation types generally dominated by a highly diverse flora of herbaceous plants and shrubs (Zhang et al. 2008). These intermix with conifer forests of primarily fir, spruce, and juni- pers in protected ravines and gorges. Rhododen- dron thickets are a conspicuous feature of the landscape, especially where Sichuan, Xizang, and Yunnan meet. They are best developed on sites protected from direct solar radiation, which can cause heating and drying of the soil, a phenomenon also noted on south-facing slopes in northern Myanmar (Burma) by Ward (1937). Alpine meadows, in the broad sense, typically dominated by species of Kobresia (bog sedges), are used for grazing throughout the region, par- ticularly in the summer when herds of sheep, goats, and especially yaks are moved to higher elevations by the semi-nomadic Tibetan pas- toralists. Most of the area is so heavily grazed that herbaceous plants survive only by growing In Sichuan, just west of Gongya Xiang along the Serqu River. Three generations of Tibetan Buddhist pilgrims on a journey Lhasa. At this point they were still 1410 kilometers (876 miles) from their destination with six months of walking to go. Hengduan Hotspot 29 Wang Qia photographing plants at Haizi Shan, an extensive cold, glaciated plateau with numerous lakes, ponds, and streams that often flow out of sight under the glacial debris. up through the middle of shrubs, which offer some protection from the animals. The reason that so many herbarium specimens of herba- ceous plants from these areas lack underground organs is because of the difficulty in extracting them from the middle of the coarse, frequently spiny shrubs in which they grow. BIODIVERSITY High diversity is generally associated with equi- table, tropical climates. In contrast, the Heng- duan region can experience snow, hail, freezing rain, and below freezing temperatures on any day of the year. Temperatures of -40°C (-40°F) and driving wind and snow are not unusual in the winter, yet plant diversity approaches that of the tropics. The vascular plant diversity is truly impressive, with as many as a third of China's vascular flora of 3 1,500 species growing just in the Hengduan regions. Of those, at least 3,500 species, including about 100 ferns and 20 gymnosperms, plus more than 30 genera of vas- cular plants, occur nowhere else in the world. The diversity is also unusual in that a large proportion of species occur in relatively few, but characteristic, Hengduan genera: Rhodo- dendron (226 species), Pedicularis (217), Sau- ssurea (100+), Ligularia (70), Cremanthodium (38), Anaphalis (33), Leontopodium (25), Arte- misia (55), Gentiana (117), Primula (113) Saxi- fraga (136), Salix (103), and Corydalis (89). EARLY EXPLORATION The first western explorers (and essentially the first naturalists) in the area were French mis- sionaries who traveled to the remotest regions of China to convert the locals to Christianity (Kilpatrick 2014). Most were also trained in the natural sciences and were encouraged to col- lect and send specimens back to Paris. Among the most notable of these missionaries were Pere Jean-Pierre-Armand David (1826-1900), the first westerner to send skins of the panda to Europe (in addition to many plant specimens); Pere lean Marie Delavay (1834-1895), who explored in western Yunnan and sent back thou- sands of plants specimens; Pere Jean-Theodore Monbeig (1875-1914), who collected and was murdered in southeast Xizang; and Jean Andre Soulie (1858-1905), who collected in western Sichuan and southeast Xizang, where he, too, was murdered. The rich and varied collections 30 Arnoldia 72/1 • July 2014 of so many unusual plants arriving in Paris, when distributed to other herbaria in Europe, prompted the nurseries and scientific institu- tions of the day to send their own collectors to gather seeds and living plants for the garden trade and for science. Western plant explorers including Joseph Rock (1885-1969), George Forest (1873-1932) and Ernest H. Wilson (1876-1930) visited parts of the Hengduan region, and Frank Kingdon- Ward touched its southern and western edges. From the 1920s to the 1940s, Chinese botanists including T. T. Yu (1908-1986), Ching Ren- Chang (1898-1986), K. M. Feng (1917-2007), C. W. Wang (1913-1987), W. P. Fang (1899-1983), and H. T. Tsai (1901-1981) made extensive col- lections along the southern and eastern edges of the area, but no comprehensive study of the entire region was undertaken until the Chinese Academy of Sciences organized a major mul- tidisciplinary expedition to the area between 1973 and 1980. The findings from the expedi- tion were published in Vascular Plants of the Hengduan Mountains , volumes 1 and 2 (Wang et al. 1993, 1994). Those two volumes provide detailed documentation on the plants of the area, not only those gathered on Chinese expe- ditions, but also specimens made by earlier Chinese and western collectors. I and several colleagues have made numer- ous trips to document the biodiversity of the Hengduan region. Our own expeditions avoided areas where others had been, since the Harvard Herbaria are already richly repre- sented by specimens from those areas. Instead, we focused on more remote regions and those that had been closed to the earlier explorers for various reasons. THE FLORA The Hengduan hotspot is botanically one of the richest temperate regions in the northern hemisphere. The high species diversity and endemism derives from the extremes of topog- raphy and climate, the island-like isolation of numerous high peaks and ridges, and the wide diversity of habitats they harbor. Broadleaved and coniferous forests, bamboo groves, scrub communities, savannas, meadows, prairies, freshwater wetlands, alpine scrubs, and scree slopes are among the broadly defined plant communities there (Sichuan Vegetation Study Group 1980). Because of the complex local geomorphology, the north-south orientation of the mountains, and the huge vertical differ- ences in topography, vertical zonation of the vegetation is also well developed (Zhang et al. 2008). Areas between 1,000 and 3,000 meters (3,281 and 9,843 feet) provided conditions for humid mixed evergreen-deciduous broadleaved forests, xeric river valley scrub, and sclerophyl- lous evergreen broadleaved forests, depending on slope and moisture conditions. The drier formations are often characterized by intro- duced Opuntia (a cactus genus) on cliffs along the dry river gorges, making them reminiscent of a West Texas landscape. Between 3,000 and 4,000 meters (9,843 and 13,123 feet) are subalpme coniferous forests dominated by Pinus densata, Picea likiangen- sis, other species of Picea, and Abies squamata, as well as by deciduous broadleaved species of Betula (birch), Populus (poplar), Acer (maple), Quercus (oak), Prunus (cherry), Tilia (linden), Fraxinus (ash) and Sorbus (mountain ash). Above 3,800 meters (12,467 feet) are alpine scrub and alpine meadows dominated by Cyperaceae (sedge family) members, particularly Kobresia (bog sedge). The subalpine scrub vegetation is dominated by shrubs of Rhododendron, Juni- perus, Caragana (peashrub), Artemisia, Salix (willow), and a complex number of forms of Dasiphora (syn. Potentilla ) fruticosa and D. glabra. Species of Kobresia, Arenaria (sand- wort), Bistorta, Aster, Saussurea, Pedicularis (lousewort), various Apiaceae (carrot family), Primula (primrose), Allium (onion), Cyanan- thus, Corydalis, Astragalus, Hedysarum and Oxytropis dominate the alpine meadows. On steep slopes at 4,500 meters (14,764 feet), the alpine scrub and meadows are replaced by alpine scree vegetation or by stony soils that pro- vide habitat for numerous interesting endemic species of Saussurea, Corydalis, Solms-laubachia and other Brassicaceae (mustard family), and Meconopsis (a genus in the poppy family), or by high cold grasslands or high cold desert mead- ows where the major species are members of Stipa, Kobresia, Carex, Arenaria, Bistorta and Artemisia. The photos on the following pages provide just a small sample of the floristic rich- ness of this unique and fascinating region. Sichuan, Baiyu Xian, Zhandu Xiang. Mixed conifer-mixed broadleaved deciduous forests, with Salix (willow) growing near the stream, along a branch of the Ou Qu in Ase Gou (Ase Gorge). References Cited Boufford, D. E. and P. P. van Dijk. 2000. South-Central China, pp. 338-351, in R. A. Mittermeier, N. Myers, and C. G. Mittermeier, eds. Hotspots: Earth’s biologically richest and most endangered terrestrial ecoregions. Mexico City: CEMEX/Agrupacion Sierra Madre. Boufford, D. E. and H. Ohba. 1998. Sino-Japanese Flora: Its Characteristics and Diversification. University Museum, University of Tokyo, Bulletin 37. Eaton. D. A. R., C. B. Fenster, f. Hereford, S. Q. Huang and R. H. Ree. 2012. Floral diversity and community structure in Pedicularis (Orobanchaceae). Ecology 93(8) Supplement S182-S194. Kilpatrick, J. 2014. Fathers of Botany: Missionary- Botanists and the Western Discovery of Chinese Plants 1862-1914. In press, to be published by Royal Botanic Gardens, Kew, and University of Chicago Press, autumn 2014. Li, Z. Y. and L. Shi. 2007. Plants of Mount Emei. Beijing: Beijing Science and Technology Press. Sichuan Vegetation Study Group. 1980. Sichuan Zhibei (Vegetation of Sichuan). Chengdu: Sichuan People's Press. Wang, H. and D. Z. Li. 2005. Pollination biology of four Pedicularis Species (Scrophulariaceae) in northwestern Yunnan, China. Annals Missouri Botanic Garden 92: 127-138. Wang, W. T., S. G. Wu, K. Y. Lang, P. Q. Li, F. T. Pu, and S. K. Chen (eds.). 1993. Vascular Plants of the Hengduan Mountains. Vol. 1, Pteridophyta, Gymnospermae, Dicotyledoneae (Saururacea to Cornaceae). Beijing: Beijing Science and Technology Press. Wang, W. T., S. G. Wu, K. Y. Lang, P. Q. Li, F. T. Pu and S. K. Chen (eds.). 1994. Vascular Plants of the Hengduan Mountains. Vol. 2, Dicotyledoneae (Diape nsiaceae to Asteraceae) to Monocotyledoneae (Typhaceae to Orchidaceae). Beijing: Beijing Science and Technology Press Ward, F. K. 1937. Plant Hunter’s Paradise. London: J. Cape. Williams, P., T. Ya, Y. Jian, and S. Cameron. 2009. The bumblebees of Sichuan (Hymenoptera: Apidae, Bombini). Systematics and Biodiversity 7(2): 101-189. Wu, Z. Y. 1988. Hengduan Mountain flora and her significance. Journal Japanese Botany 63: 297—3 1 1 . Zhang, D. C., Y. H. Zhang, D. E. Boufford, and H. Sun. 2008. Elevational patterns of species richness and endemism for some important taxa in the Hengduan Mountains, southwestern China. Biodiversity Conservation 18: 699-716. Published online 13 December 2008. David E. Boufford is a Senior Research Scientist at the Harvard University Herbaria. 32 Arnoldia 72/1 • July 2014 WOODY PLANTS A few of the woody plants of the Hengduan region, clockwise from upper left: • The orange fruits of Tibetan sea-buckthorn (. Hippophae tibetana ). • Immature cone of Prince Rupprecht larch ( Larix gmelinii var. principis-rupprechtii ). • Flowers of Clematis rehderiana, named in honor of Alfred Rehder. • Flowers of Dipelta wenxianensis. • Young leaves of the shrub Helwingia japonica var. papillosa, which are cooked in oil with chopped garlic and eaten as a green vegetable. • Fruits of Eleutherococcus cissifolius, a shrub in the aralia family (Araliaceae). Hengduan Hotspot 33 GENTIANACEAE Gentians ( Gentiana ) and their relatives, notable for blue flower color, are characteristic of the Hengduan flora. Of the 248 species of Gentiana in China, 117 occur in the Hengduan region. Clockwise from upper left: • Gentianopsis contorta • Gentiana crassicaulis • Lomatogonium perenne • Gentiana aristata • Comastoma falcatum • Gentiana atuntsiensis The Asteraceae (aster or composite family) is another diverse plant group in the Hengduan region. Saussurea, Ligularia, Cremanthodium, Anaphalis, and Leontopodium (edelweiss) are among the most species-rich genera in the Hengduan region. Clockwise from upper left: • Saussurea Stella displays showy purple leaf bases. • Saussurea obvallata has translucent bracts that form a protective globe around the small purple flowers within. • These Anaphalis inflorescences feature pearly white bracts. • Cremanthodium humile growing on a scree slope. • The foliage of Saussurea pilinophylla is densely covered with soft hairs. • Because it grows at elevations as high as 5,000 meters (16,404 feet), Rhodiola crenulata is believed to have special medicinal properties and is being extirpated by herb collectors throughout its range. Hengduan Hotspot 35 PEDICULARIS Pedicularis has its main center of distribution in the Heng- duan Mountain region, where 217 of China's 352 species occur. The plants are reported to be hemiparasitic, getting at least part of their nutritional needs from host plants. Despite many attempts, we have been unsuccessful in exca- vating the underground parts to find the connections with a host plant. While easy to recognize vegetatively as being a species of Pedicularis, the flowers are needed for identi- fication to the species level. The beak (galea) and orienta- tion of the corolla appear to be correlated with pollination by bumblebees (Eaton et al. 2012; Wang and Li 2005). The Hengduan region, with 65 species, is also the world's center of diversity for bumblebees (Williams et al. 2009). Clock- wise from upper left: • Pedicularis stenocorys • Pedicularis siphonantha (two color forms within same population) • Pedicularis alopecuros • Pedicularis kansuensis • Pedicularis mollis • Pedicularis armata var. trimaculata A Shady Character: Platanus x acerifolia Nancy Rose O n hot, sunny summer days, visitors gravitate toward the Arboretum's magnificent old specimen trees whose dense, leafy canopies provide welcome shade. One such specimen is a centenarian London planetree ( Platanus x acerifolia, accession 16595-B) growing in a prominent location near the juncture of Bussey Hill Road and Valley Road. This stately tree was accessioned in April 1891, received as a plant from Thomas Meehan and Son nursery in Philadelphia. With an age of about 125 years, it currently measures 31 meters (102 feet) tall, 24.5 meters (89 feet) wide, and has a trunk dbh (diameter at breast height) of 132.5 centimeters (52 inches). London planetree was long considered to be a hybrid of Oriental planetree ( Platanus orien- talis ) and American sycamore [P. occidentalis), though it required modern molecular analysis to prove this definitively. The species' exact origin and correct scientific name have been the subject of debate over the years. The parent species are from Eurasia and North America, respectively, so it was only through human transportation of germplasm between conti- nents that they were able to hybridize. The first hybrid may have occurred at the Oxford Botanic Garden around 1670, though an ori- gin in Spain has also been suggested. The first recorded binomial was Platanus hispanica in 1770, followed by P. hybridus in 1804, then P. acerifolia in 1805. Current references are split, with some listing P. x acerifolia (Ait.) Willd. and others Platanus x hispanica Mill, ex Miinchh. as the accepted name. Because of its hybrid nature, seed-grown Lon- don planetrees can be quite variable in growth habit, leaf shape, and fruit production. This is further compounded by potential backcross- ing with either of the parent species. Mature London planetrees typically have a spreading crown and substantial trunk, and reach a height of 60 to 90 feet (18.3 to 27.4 meters) or more. The large (up to 10 inches [25.4 centimeters] wide) leaves have 3 to 5 lobes and are medium green with limited yellowish fall color. Male and female flowers are borne separately in globose inflorescences,- the bumpy, tan, golf- ball-sized fruit holds multiple achenes. The fruit are usually borne in groups of 2 and may persist well into winter before breaking apart. London planetree's most notable ornamental feature is its thin, exfoliating bark that displays a camouflage-like pattern in shades of white, brown, and green. A number of London planetree cultivars have been selected and vegetatively propagated; these cultivars are often preferred over seed-grown plants in landscapes where uniform tree shape and size is desirable. The species can be affected by several diseases including anthracnose, pow- dery mildew, and canker stain, so disease resis- tant cultivars have been especially sought after. The original "London" form (which lead to the common name) was likely a clonal selection, though "London planetree" is now widely used to denote the species as a whole. Because of its large size and abundant leaf and fruit litter, London planetree is not ideal for many residential lots, especially small city lots. It is best reserved for sites where it can achieve its full stature, such as parks, public gardens, and campuses. London planetree is noted for its tolerance of heavy pruning and is often pruned and trained to limit crown growth, especially in Europe. Pollarding, a severe type of pruning that heads back growth to short, knobby limbs, is commonly practiced on Lon- don planetrees in European park and boulevard plantings. At the Arboretum, accession 16595-B and surrounding London planetrees have been allowed to grow in their natural, wide-spreading form, thus providing a shady haven during the dog days of summer. Nancy Rose is the editor of Arnoldia. n i /* *5 1 / 25/14 Pi. 10 4, r .J. Jofy i*Y//y American Chesnut ( (ht'tanca vtsca ^WWffliV.u tNOV 2 5 2014 A f. ‘FA CRAY HERBARIUM ^ LIBRARY amoldia The Magazine of the Arnold Arboretum VOLUME 72 • NUMBER 2 • 2014 CONTENTS J 6 £^7 f Amoldia (ISSN 0004-2633; USPS 866-100) is published quarterly by the Arnold Arboretum of Harvard University. Periodicals postage paid at Boston, Massachusetts. Subscriptions are $20.00 per calendar year domestic, $25.00 foreign, payable in advance. Remittances may be made in U.S. dollars, by check drawn on a U.S. bank; by international money order; or by Visa, Mastercard, or American Express. Send orders, remittances, requests to purchase back issues, change-of-address notices, and all other subscription-related communica- tions to Circulation Manager, Amoldia, Arnold Arboretum, 125 Arborway, Boston, MA 02130- 3500. Telephone 617.524.1718; fax 617.524.1418; e-mail arnoldia@arnarb.harvard.edu Arnold Arboretum members receive a subscrip- tion to Amoldia as a membership benefit. To become a member or receive more information, please call Wendy Krauss at 617.384.5766 or email wendy_krauss@harvard.edu Postmaster: Send address changes to Amoldia Circulation Manager The Arnold Arboretum 125 Arborway Boston, MA 02130-3500 Nancy Rose, Editor Andy Winther, Designer Editorial Committee Phyllis Andersen Peter Del Tredici Michael S. Dosmann William (Ned) Friedman Kanchi N. Gandhi Copyright © 2014. The President and Fellows of Harvard College JR ARNOLD ARBORETUM of HARVARD UNIVERSITY 2 Hamamelidaceae, Part i: Exploring the Witch-hazels of the Arnold Arboretum Andrew Gapinski 1 8 Did American Chestnut Really Dominate the Eastern Forest? Edward K. Faison and David R. Foster 33 Reading Tree Roots for Clues: The Habits of Truffles and Other Ectomycorrhizal Cup Fungi Rosanne Healy 40 The Castor Aralia, Kalopanax septemlobus Kyle Port Front cover: Flowers of a hybrid witch-hazel cultivar, Hamamelis x intermedia 'Jelena' (accession 462-65-A). Photo by Kyle Port. Inside front cover: Illustration of American chestnut ( Castanea dentata) from Franqois Andre Michaux's The North American Sylva, Volume 3, published in 1819. Note that the illustration uses the old synonym C. vesca and an alternate spelling of the common name, "chesnut." Inside back cover: The leaves of Kalopanax septemlobus accession 84 1-81 -A, which grows near the Arboretum's Rehder Pond, developing bright greenish yellow fall color. Photo by Kyle Port. Back cover: Fall-flowering common witch-hazel (Hamamelis virginiana ) blooms in a Minnesota garden. Photo by Nancy Rose. KYLE PORT Hamamelidaceae, Part 1: Exploring the Witch-hazels of the Arnold Arboretum Andrew Gapinski H amamelidaceae, the witch-hazel family, includes approximately 30 genera repre- senting around 100 species of deciduous trees and shrubs. Members of the family are found in both temperate and tropical regions of North and Central America, Eastern Asia, Africa, the Pacific Islands, and Australia. The Arnold Arboretum has a rich history with the family, from plant exploration to the naming and introduction of its members to cultivation. The Arboretum's Hamamelidaceae collection, which currently comprises ten temperate region genera, can be found in groupings throughout the Arboretum landscape. Specific locations Many witch-hazels display attractive fall color; seen here, Hamamelis x intermedia 'Arnold Promise' (accession 380- 94-C) with red orange foliage and Hamamelis virginiana f. rubescens (accession 527-92) with yellow foliage. Hamamelidaceae, Part 1*3 All In the Family The Arnold Arboretum currently has living specimens representing these genera within Hamamelidaceae: Corylopsis Fortunearia Fothergilla Hamamelis Liquidambar Loropetalum Parrotia Parrotiopsis Sinowilsonia x Sycopanotia Chinese winter-hazel ( Corylopsis sinensis)-, American sweetgum ( Liquidambar styraciflua )• Large fothergilla ( Fothergilla major ) include the area around the Hunnewell Visitor Center, the Leventritt Shrub and Vine Garden, scattered among the trees in the North Woods, on the edges of the hickory (Cary a) collection, near the summit of Bussey Hill, and among the jewels of the Explorers Garden. As autumn arrives at the Arboretum, the flow- ering season for the witch-hazel family begins, and will carry through until spring. Starting in October, common witch-hazel (Hamamelis virginiana ) — a New England native — begins to bloom, the straplike yellow petals of its fragrant flowers extending on warm days and curling up when temperatures drop near freezing. This show can persist into December even as the snow begins to fall. Other members of the witch- hazel genus represent the earliest of bloomers, starting in January and lasting well into March — a remarkable sight in the depths of winter. As the ground begins to warm in April, sev- eral species of Corylopsis — commonly called the winter-hazels — produce many pendulous clusters of bell-shaped yellow flowers. The fothergillas (Fothergilla) round out the family's flowering season in the Arboretum with their bottle-brush-like white blooms in May. Beyond the showy flowering of these genera, many are also aesthetically valuable for their unique foliage, vibrant fall colors, and, in the case of Parrotia, attractive exfoliating bark. Given these attributes, perhaps no other plant group- ing holds greater ornamental potential and yet is so underutilized in today's landscape than the witch-hazel family. This two-part article explores various historical, taxonomic, and hor- ticultural facets of Hamamelidaceae taxa in the Arboretum's collection. We begin with Hama- melis, the genus for which the family is named. KYLE PORT (ALL) ANDREW GAP1NSKI 4 Arnoldia 72/2 • October 2014 Hamamelis Whilst winter's hand is yet heavy on the land the Witch-hazels boldly put forth their star-shaped yellow blossoms but the native Hamamelis vernalis is over-shadowed by its more brilliant Chinese and Japanese relatives. Ernest H. Wilson, Plant Hunting, 1927 Witch-hazel ( Hamamelis ) is the most well-known Hamamelidaceae genus among gardeners and includes the only native New England representative of the family — Hamamelis virginiana, the common witch-hazel. There are two other North American species, H. vernalis (vernal or Ozark witch-hazel) and H. ovalis (big-leaf witch-hazel), and two Asian relatives, H. mollis (Chinese witch-hazel) and H. japon- ica (Japanese witch-hazel). All of these Witch-hazel flower petals can furl and unfurl depending on air temperature. Seen here are flowers of Hamamelis mollis 'Princeton Gold'. A common witch-hazel ( Hamamelis virginiana ) in fall bloom, growing in Virginia's Shenandoah National Park. KYLE PORT Hamamelidaceae, Part 1 • 5 Yellow flowers and yellow fall foliage blend on the branches of this common witch-hazel. species are shrubs or small trees inhabiting temperate regions. They share charac- teristically narrow, straplike flower petals and capsulate fruit that is explosively dehiscent, capable of eject- ing seeds as far as 10 meters (33 feet). Much work has been done to create hybrids [H. x intermedia) between the Chinese and Japanese species, resulting in the development of horticul- turally desirable selections. Today these hybrids, as well as cultivars of H. mollis, are the witch-hazel family members most popular with American gardeners. Both the North American and Asian witch-hazels have a rich history, with fascinating stories of discovery and much hor- ticultural potential. North American Discoveries Common witch-hazel has a wide-ranging native distribution along the east coast from Nova Scotia to Florida and west to the Mississippi River, petering out in the Ozarlcs. Its western limit runs from eastern Texas to Minnesota. It is commonly found in forest understories as a large multi-stemmed shrub. For non-gardeners, witch-hazel may be a familiar name not as a forest-dweller but for its use as a component in first-aid and skincare products. Native Ameri- cans used witch-hazel for its healing properties, and open-minded New Englanders soon recog- nized its potential. In 1866, the first commercial witch-hazel extract distillery was founded in Essex, Connecticut, by Thomas Newton Dick- inson. Today, the distilling facility is located in East Hampton, Connecticut, and is the world's largest source of witch-hazel extract, still pro- duced from witch-hazel wild-harvested from New England's woodlands. The flowering time of common witch-hazel is definitely unique. Just as it seems that the last of the years' blooms have faded, H. vir- giniana comes into flower. Depending on the specimen in question, blooms start as early as October and can last into December. The spe- cies' fragrant flowers are composed of four yel- low, straplike petals that furl and unfurl with the temperature swings of late autumn. In many cases, full bloom occurs when the plant's yellow fall foliage is still present, making it dif- ficult to appreciate the flowers' full grandeur. This is viewed by some as an aesthetic fault of the plant, hut to those who know what to look for, it is quite a remarkable display. With noth- ing else in bloom, the common witch-hazel has little competition for pollinators seeking a late season food source. The Arboretum's largest concentration of H. viriginiana can be found in the North Woods, just past the Aesculus collection along Meadow Road, uphill from the short stretch of post-and- rail fence. A visit to explore this nook should be part of any autumn walk in the Arboretum. A bit farther down Meadow Road, at the northern end of Rehder Pond, is the Arboretum's oldest accession (14693-D) of common witch-hazel, wild-collected as a plant from western Massa- chusetts and brought back to the Arboretum in 1883 by Jackson Thornton Dawson, the Arbo- retum's first plant propagator. Steps away from this specimen grows another one of the Arboretum's centenarian witch- MICHAEL DOSMANN 6 Arnoldia 1212 . October 2014 hazels, Hamamelis vernalis accession 6099-D. Unlike common witch-hazel, the vernal witch- hazel, as the name suggests, flowers very early in the year (January through March). Although its geographic range overlaps with that of com- mon witch-hazel, it only grows natively in the Ozark highlands of Missouri, Arkansas, and Oklahoma, and in small populations in Texas and Louisiana. A truly grand representation of the species, accession 6099-D was wild- collected as a seedling in Missouri and sent to the Arboretum in 1908 by Benjamin Franklin Bush under the consignment of Charles Sprague Sargent, the Arboretum's first director. At the time of this plant's collection, H. vernalis had yet to be officially named and described by science, although, as herbarium records show, it was found growing in Missouri by Saint Louis botanist Dr. George Engelmann as early as 1845. Nonetheless, common witch- hazel was the only identified North American species at this point. In fact, Bush authored the 1895 publication A list of the trees, shrubs and vines of Missouri in which H. virginiana is mentioned as the sole representative of the genus. Sargent's 1890 publication The Silva of North America, a description of the trees which grow naturally in North America exclusive of Mexico, made the same conclusion. The story of vernal witch-hazel's discovery begins with Sargent's and Bush's plant explora- tions in Missouri and Arkansas in September- October of 1907, the main goal of which was to search for new Crataegus (hawthorn) species. On October 8, 1907, the explorers collected a herbarium specimen in Swan, Missouri, of a Hamamelis in fruit, but lacking flowers,- this certainly sparked their curiosity since it appeared dissimilar to the known fall-blooming species, H. virginiana. Returning to Boston, Sargent anxiously requested of Bush that he return to Missouri to collect seeds and flower- ing herbarium specimens that winter. In a letter to Bush dated January 22, 1908, Sargent wrote, "Are you doing anything about the flowers of that Southern Missouri Hamamelis ? I am very anxious to get these this spring if possible and Flowers and old seed capsules of a 1908 accession of Hamame- lis vernalis (6099-D) growing near Rehder Pond. I am counting on you to do it, either through our friend at Swan or through your brother." Sargent received his first flowering vouchers of the suspicious witch-hazel on March 14, 1908, and wrote: Dear Mr. Bush: I am very much obligated for the Hamame- lis specimens which arrived today. They were gathered a little too soon and if you had only put them in water a few days before pressing then the flowers would have fully expanded. I think there is no doubt, however, that this is an undescribed species. We want to describe and publish a figure of it in an early number of Trees and Shrubs, so I hope you won't "give it away" to anyone else ... We must manage to get some young rooted plants of the Hamamelis as none of the seeds we got last autumn were good. Apparently after they were gathered they were destroyed by the weevil . . . Yours very truly, C. S. Sargent Original October 8, 1907, herbarium voucher of Hamamelis sp. collected by B. F. Bush and C. S. Sargent in Swan, Missouri. This collection would lead to further investigation and the naming of a new North American witch-hazel species — Hamamelis vernalis — by Sargent in 1911. Note that the specific epithet “vernalis” was later added to the original description. ROBERT MAYER Material from Packet Meyer A)J So-Vj*^ I TnJO, < X 01 C ' ' ' 1 1 U. S. NATIONAL ARBORETUM HERBARIUM. WASHINGTON. D. C ^RBARlGr OF THE \ ARNOLD ARBORETUM ; ^ VAtip univE S^V^ i *.-ynlf*A 3-t>. $\AsTisyi, j jyti . (SUt.r,iwr. 7 " Vegetative specimen of Humamelis from an area where H. X vernalis Sarg. aiul //. vtrginiana L. vur. virginiana both occur. Positive determination uncertain, dependent upon floral structures. Examined at Vanderbilt University in a study of variation in North American llamamelix 1.. f Hamamelidaceae). Gertrude E. Jenne 196S ARNOLD ARBORETUM l'l.ANT.S OF .Missorui (JoLI.KI TKD BY K. V. BIJRJI. kt A- r>yjJL l& %. , f < n^ ( ?yu, fay*.. 2 <7 'HOt. Hanwmeli . X vernal u Sarg. (pro

□ >40% A . V, -+) 4 ' - P V* ‘*)P * • • r '■ BEECH Pre-Colonial Relative Abundance □ Absent □ 0 to 2.5% □ 2.5 to 5% □ 5 to 10% □ 10 to 20% □ 20 to 40% ■ >40% A * •* J#Vr * - ■ /owC't* 2 % •• t ' ^ •/ • ± n * r * American chestnut abundance compared with American beech and eastern hemlock abundance in the Northeast at the time of European settle- ment as determined by early land survey data (Thompson et al. 2013) of trees in a single town. In contrast, beech comprised 22% of trees across the region; oaks, predominantly white oak, 17.5%; and hemlock 11%. Two decades ago, forest historian Gordon Whitney compiled maps of tree species abun- dance from land survey data across the mid- western United States. Data from about 100 counties or townships across eight states of the upper Midwest reveal that chestnut was never the dominant tree, comprising 5 to 15% of trees in a small section of Ohio and 0 to 4% of trees in the rest of the region. In contrast, beech and especially white oak were frequently the dominant tree, often comprising 25 to 65% of all trees. Limited early land survey data from the southern regions of the eastern forest also portray chestnut as a secondary species. Chest- HEMLOCK Pre-Colonial Relative Abundance □ Absent □ 0 to 2.5% □ 2.5 to 5% □ 5 to 10% □ 10 to 20% □ 20 to 40% > ■ >40% *’ * * a ' * V -W jif k p^Vf»4 * f VI * w 24 Arnoldia 72/2 • October 2014 Dominant tree species and corresponding abundance and rank of American chestnut at the time of European settlement identified from early land survey data in the southeastern United States. Adapted from Abrams (2003). Location Dominant Tree Species Chestnut Chestnut Reference and Abundance (%) Abundance (%) Rank Eastern West Virginia - Ridge and Valley White oak (33) 5 5 Abrams and McCay 1996 Eastern West Virginia - Allegheny Mts. Beech (13) 6 8 Abrams and McCay 1996 Southern West Virginia White oak (24) 12 2 Abrams et al. 1995 Northern Virginia White oak (49) 0 NA Orwig and Abrams 1994 Southwestern Virginia Red oak (25) 9 3 McCormick and Platt 1980 Western Virginia White oak (26) 5 5 Stephenson et al. 1992 Pine, mostly loblolly Central Georgia and shortleaf (27) Post oak (18) 2 9 Cowell 1995 Northeastern Georgia Pine (26) American chestnut (20) 20 1 Bratton and Meier 1998 Southcentral Tennessee Post Oak (11) 2 11 DeSelm 1994 Northern Florida Magnolia (21) 0 NA Delcourt and Delcourt 1977 Southeastern Texas Pine, mostly longleaf (25) 0 NA Schafale and Harcombe 1983 Southeastern Louisiana Magnolia (13) 0 NA Delcourt and Delcourt 1974 Pine, longleaf, shortleaf, Northeastern Louisiana and loblolly (24) White oak (11) 0 NA Delcourt 1976 Eastern Alabama Pine, 7 species (44) Post oak (12) 2 9 Black et al. 2002 Southern Arkansas Black oak (18) 0 NA Bragg 2003 American Chestnut 25 A white oak ( Quercus alba ) in New Braintree, Massachusetts. nut was the first-ranked species in only one of 15 locations, whereas white oak was the first- ranked tree in five of 15 locations (see Table on facing page). Early Twentieth Century Forest Surveys E. Lucy Braun conducted and compiled exten- sive forest surveys and observations across 120 counties of the eastern forest in the early twen- tieth century. Her data were predominantly gathered from "original" forests and thus fill in gaps in the witness tree studies, particularly in regions such as the Cumberland Mountains of Kentucky and the Blue Ridge Mountains of North Carolina and Tennessee. Although Braun acknowledged her unequal coverage of different regions, her work remains by far the most com- prehensive assessment of the eastern deciduous forest, including American chestnut's abun- dance, at the time of the chestnut blight. Her surveys and data tables reveal that chestnut was a tree of surprisingly limited dominance. Chest- nut was dominant (the most abundant canopy tree) in at least one survey in only 15 of the 120 counties (12.5%) sampled by Braun and others. Sugar maple, white oak, and hemlock were all dominant species in over 20% of the counties sampled, and beech was a dominant tree in over 40% of the counties sampled. In fact, Braun's data suggest that chestnut was not even the most abundant tree within its own geographic range: beech was a dominant species in at least one survey in almost half (48%) of the counties sampled in chestnut's range, whereas chestnut was a dominant tree in less than a quarter (23%) of the counties sampled. American chestnut was spectacularly abun- dant in some locations. On north slopes in foyce JOHN S, BURK HARVARD FOREST ARCHIVES, HARVARD UNIVERSITY 26 Arnoldia 72/2 • October 2014 Kilmer Memorial Forest in North Carolina, for instance, it comprised over 83% of the canopy trees, and on the slopes of Salt Pond Mountain in western Virginia, it made up 56 to 85% of the canopy trees (Braun 1950). Chestnut could also grow to enormous size. In a forest in Central Kentucky, Braun wrote that chestnuts, which comprised 22% of the canopy trees, were "by far the largest trees, about 5 feet d.b.h. (diameter at breast height)." But chestnut was far from the only tree to achieve such local dominance; beech, hemlock, sugar maple and white oak all achieved comparable abundances in other stand locations. In 1876, forester A. R. Crandall wrote the following in eastern Kentucky: "white oak A stand of American beech ( Fagus grandifolia ) in Harvard Forest's Pisgah Tract in New Hampshire, April 1930. has a wider range and greater development in numbers than any other species. In size it ranks with the largest of the hardwood trees ..." The Rise of Nineteenth Century Logging and Chestnut In its destructiveness and lack of legal con- trol, nineteenth century commercial log- ging was similar to the unrestricted hunting that decimated the passenger pigeon and the bison. However, in an ironic twist to the story of American chestnut, this particular act of exploitation actually promoted chestnut to dominance in parts of its range where it hadn't been dominant before. Chestnut's remarkable A ring of new shoots growing around the cut stump of an American chestnut, from the image collection American Envi- ronmental Photographs, 1891-1936, University of Chicago Library Special Collections. American Chestnut 27 AMERICAN CHESTNUT w * m | r ' v ■ 9 a “ * -#7 'jJP \ 'T f l * * w-^V-1 5.0k "* ->T J 'N 400 200 0 400 Kilometers Chestnut Range Counties Sampled | Dominant Present ■ Absent American chestnut's geographic range and extent of dominance compared to that of white oak and American beech in the early twentieth century. Data compiled by Braun (1950). ability to sprout vigorously from cut stumps, including those of large diameter and advanced age, made it better adapted to intensive logging than any other hardwood tree including oaks. As the early Connecticut foresters Hawley and Hawes (1912) wrote, "this sprouting capacity of the species is its strongest characteristic and the one by which with each successive cutting it gains in the struggle for existence with the rival inmates of the woodlot." Interestingly, chestnut's sprouting capacity was much more prominent in the Northeast than in the south- ern parts of chestnut's range. In heavily cutover forests of northern New Jersey and southern New England, chestnut increased from 5 to 15% of the forest during the early colonial period to an estimated 50% of the standing timber in Connecticut. Because Braun focused WHITE OAK w * ’ t a* I N 400 200 0 400 Kilometers White Oak Range Counties Sampled H Dominant Present BB Absent 28 Anioldia 1212 . October 2014 A stand of American chestnut in Big Creek Gap, Tennessee, from the image collection American Environmental Photographs, 1891-1936, University of Chicago Library Special Collections. American Chestnut 29 on "original" forests in her surveys, she largely avoided surveying the cutover southern New England region so her data probably underes- timate chestnut's abundance in the Northeast. But it's important to remember that southern New England represents a small fraction of chestnut's range and the eastern forest overall. The Last to Arrive: Chestnut Since the Last Ice Age Fossil pollen records in the Eastern forest enable reconstruction of vegetation communi- ties and tree species that have dominated for- ests over the past 15,000 to 50,000 years. In formerly glaciated areas such as the Northeast, pollen records provide a chronological record of recolonization of forest vegetation after glacial melt some 15,000 to 20,000 years BP (before present). In southern New England, ash ( Fraxi - nus), birch ( Betula ), ironwood (both Ostrya and Carpinus, whose pollens are indistinguishable from each other), and oak arrived first, followed by maples, • deciduous forests replaced conifer- ous forests about 9,000 years BP. Beech arrived about 8,000 years BP, and hickory about 6,000 years BP. Not until about 2,000 years BP does chestnut pollen appear in the sediment record, earning chestnut the distinction of being the last major tree species to recolonize the region SPATIAL SCALE Spatial scale refers to the size or extent of the area under consideration. A stand is a relatively small area of forest that is spatially continuous in struc- ture and composition and is exposed to similar soil and climatic conditions. In paleoecology the size of the catch basin (e.g., lake, pond, swamp, or small hollow) determines the distance from which pollen in the sediments originates. Sediments from a small forest hollow will contain pollen from vegetation growing predominantly in the immediate stand (a "stand scale" investigation), whereas sediments from a large lake are dominated by pollen from the broader landscape up to 20 miles away. after deglaciation (Davis 1983). When chestnut finally does appear in the sediment record, it generally doesn't exceed about 4 to 7% of the pollen types across the region with the excep- tion of one record in northwestern Connecti- cut where it reaches 18 to 19% (Paillet 1991, Oswald et al. 2007). In contrast, oak pollen consistently comprises 40 to 60% of the pol- len and beech 5 to 20%. Interestingly, chestnut does achieve great dominance (40 to 70%) at the stand scale in a few local New England pol- len records (Foster et al. 1992, 2002), exemplifying the importance of spatial scale when considering the abundance of this species. What accounts for chestnut's late arrival to New England? One possi- ble reason is that the climate of the Northeast throughout much of the Holocene was too dry for chestnut. Other researchers have posited a lack of favorable well-drained germination sites in southern New England after deglaciation, or too much lime in the soil that took millennia to leach away. Chestnut is also self-sterile unlike many other trees that are self-fertile, and thus the chances of establishing new populations were much lower for this tree. Whether dispersal or envi- ronmentally limited, it is clear that A micrograph of American chestnut pollen. MISSOURI BOTANICAL GARDEN, WWW.BOTANICUS.ORG 30 Arnoldia 72j2 • October 2014 chestnut was poorly adapted to recolonizing the deglaciated Northeast compared to other hardwood trees. Chestnut had a much longer history in the unglaciated Southeast. Chestnut pollen appears in the pollen record as early as 16,000 years BP in Tennessee (Davis 1983). Although a few records show chestnut to be dominant or co-dominant with oaks during the Holocene in the North Carolina and Tennessee moun- tains, most of the records from the southern and central Appalachians analyzed by William Watts, Paul and Hazel Delcourt, and others reveal oaks to be dominant over chestnut. Still, comparisons between oak and chestnut pollen abundance should be undertaken with caution. Oak pollen grains are indistinguishable among species, and many are therefore combined into a single category of "oak" pollen. Chestnut, on the other hand, is the only species in its genus in the Northeast and is one of two species (the other is dwarf chinkapin, Castanea pumila ) in the central and southern Appalachians. Oak pollen is wind dispersed and therefore is gen- erally produced in larger quantities than is chestnut pollen, which is partially dispersed by insects. Hence, chestnut pollen is generally underrepresented in the pollen record, rela- tive to oaks. Still, chestnut's relatively minor status in the pollen record is consistent with its secondary status in the witness tree data and in accounts by early settlers. In addition, An illustration of dwarf chinkapin ( Castanea pumila ) from Mark Catesby's The Natural History of Carolina, Florida, and the Bahama Islands, Volume 1. This etching was first published in 1729. American Chestnut 31 chestnut's great abundance (40 to 45%) in a few southern Appalachian pollen records ana- lyzed by the Delcourts and stand-level records from Massachusetts are consistent with twen- tieth century forest surveys in which chestnut achieved great dominance in some landscapes and topographic positions, but generally not at broader scales. Concluding Thoughts American chestnut was once a common tree species throughout its Appalachian Moun- tain range and a dominant species in parts of its central and southern range (primarily the oak-chestnut forest region). However, prior to European settlement, it was less dominant than white oak and beech and far less wide- spread than most other major tree species. With increasing timber harvesting in the nineteenth and early twentieth centuries, chestnut's domi- nance increased in the northern part of its range in heavily cut-over forestland. Still, the tree remained absent from fully two-thirds of the eastern forest, precluding it from ever being the dominant tree of this biome. Revealing the truth about American chest- nut's relatively limited place in the Eastern forest does not diminish the grandeur of this great tree, its historical importance to cultures of the central and southern Appalachians, and the great tragedy of its demise. Chestnut remains the flagship example of the potential dangers posed by introduced pathogens in our native forests. But we should be careful not to let a great tragedy and impassioned restoration efforts trump the available data when discuss- ing the history of this tree. References: Abrams, M. D. 2003. Where has all the white oak gone? Bioscience 53: 927-939. Abrams, M. D. ; D. A. Orwig, and T. E. DeMeo. 1995. Dendroecological analysis of successional dynamics for a presettlement-origin white pine- mixed oak forest in the southern Appalachians, USA. Journal of Ecology 83: 123-133. Abrams, M. D., D. M. McCay 1996. Vegetation-site relationships of witness trees (1780-1856) in the presettlement forests of eastern West Virginia. Canadian Journal of Forest Research 26: 217-224. American chestnut research and restoration project. 2014. http://www.esf.edu/chestnut/background.htm Bartram, W. A. 1976. Travels and Other Writings. Princeton: Princeton University Press. Black, B. A., H. T. Foster, and M. D. Abrams. 2002. Combining environmentally dependent and independent analyses of witness tree data in east-central Alabama. Canadian Journal of Forest Research 32: 2060-2075. Bolgiano, C. and G. Novak. 2007. Mighty Giants: an American Chestnut Anthology. American Chestnut Foundation, Bennington, VT. Bragg, D. C. 2003. Natural presettlement features of the Ashley County, Arkansas area. The American Midland Naturalist 149:1-20. Bratton, S. P. and A. J. Meier. 1998. The recent vegetation disturbance history of the Chattooga River Watershed. Castanea 63: 372-381. Braun, E .F. 1950. Deciduous Forests of Eastern North America. Caldwell, New Jersey: The Blackburn Press. Burnham, C. R. 1988. The restoration of the American chestnut. American Scientist 76: 478M-87. Cowell, C. M. 1995. Presettlement Piedmont forests: patterns of composition and disturbance in central Georgia. Annals of the Association of American Geographers 85: 65-83. Davis, M. B. 1983. Quaternary history of deciduous forests of eastern North America and Europe. Annals of the Missouri Botanical Garden 70: 550-563. Delcourt, H. R. 1976. Presettlement vegetation of the north of Red River Band District, Fouisiana. Castanea 41: 122-139. Delcourt, H. R. 1979. Fate quaternary vegetation history of the eastern Highland Rim and adjacent Cumberland Plateau of Tennessee. Ecological Monographs 49: 255-280. Delcourt, H. R and P. A. Delcourt. 1974. Primeval magnolia-holly-beech climax in Fouisiana. Ecology 55: 638-644. 32 Arnoldia 72j2 • October 2014 Delcourt, H. R. and P. A. Delcourt. 1977. Presettlement magnolia-beech climax of the Gulf coastal plain: quantitative evidence from the Apalachicola River bluffs, north-central Florida. Ecology 58: 1085-1093. Delcourt, P. A. and H. R. Delcourt. 1998. The influence of prehistoric human set fires on oak-chestnut forests in the southern Appalachians. Castanea 63: 337-345. Delcourt, P. A., FF. R. Delcourt, P. A. Cridlebaugh, and J. Chapman. 1986. Holocene ethnobotanical and paleoecological record of human impact on vegetation in the Little Tennessee River Valley, Tennessee. Quaternary Research 25: 330-349. DeSelm, H. R. 1994. Vegetation results from an 1807 land survey from southern middle Tennessee. Castanea 59: 51-68. Foster, D. R., T. Zebryk, P. Schoonmaker, and A. Lezberg. 1992. Post-settlement history of human land-use and vegetation dynamics of a Tsuga canadensis (hemlock) woodlot in Central New England. Journal of Ecology 80: 773-786. Foster, D. R., S. Clayden, D. A. Orwig, B. Hall, and S. Barry. 2002. Oak, chestnut, and fire: climatic and cultural controls of long-term forest dynamics in New England, USA. Journal of Biogeography 29:1359-1379. Hawley, R. C. and A. F. Hawes. 1912. Forestry in New England. New York: John Wiley and Sons. Little, E. L., Jr. 1971. Atlas of United States trees, volume 1, Conifers and Important Hardwoods'. Misc. Pub. 1146. Washington, D.C.: U.S. Department of Agriculture. 9 p., 200 maps McCormick, J. F. and R. B. Platt. 1980. Recovery of an Appalachian forest following the chestnut blight or Catherine Keever — you were right! American Midland Naturalist 104: 264-273. Orwig, D. A. and M. D. Abrams. 1994. Land-use history (1720-1992), composition, and dynamics of oak- pine forests within the Piedmont and Coastal Plain of northern Virginia. Canadian Journal of Forest Research 24: 1216-1225. Oswald, W. W., E. K. Faison, and D. R. Foster. 2007. Post- glacial changes in spatial patterns of vegetation across southern New England. Journal of Biogeography 34: 900-913. Paillet, F. L. 1991. Relationship between pollen frequency in moss polsters and forest composition in a naturalized stand of American chestnut: implications for paleoenvironmental interpretation. Bulletin of the Toney Botanical Club. 118: 432-443. Russell, E. W. B. 1987. Pre-blight distribution of Castanea dentata (Marsh.) Borkh. Bulletin. Torrey Botanical Club 114: 183-190. Shuman B., P. Newby, Y. Huang, and T. Webb III. 2004. Evidence for the close climatic control of New England vegetation history. Ecology 85: 1297-1310. Smith, J. 1616. A Description of New England. Electronic Texts in American Studies Libraries at University of Nebraska-Lmcoln. Stephenson, S. L., H. S. Adams, and M. L. Lipford. 1992. The impacts of human activities on the upland forests of western Virginia. Virginia Journal of Science 43: 121-131. Thompson, J. R, D. N. Carpenter, C. V. Cogbill, and D. R. Foster. 2013. Four centuries of change in northeastern United States forests. PLoS ONE 8: e72540. Wang, G. G., B. O. Knapp, S. C. Clark, and B. T. Mudder. 2013. The Silvics of Castanea dentata (Marsh.) Borkh., American chestnut, Fagaceae (Beech Family) Gen. Tech. Rep. SRS-GTR-173. Asheville, NC: U.S. Department of Agriculture Forest Service, Southern Research Station. 18 p. Watts, W. A. 1979. Late quaternary vegetation of central Appalachia and the New Jersey coastal plain. Ecological Monographs 49: 427-469. Watts, W. A. 1980. The late quaternary vegetation history of the southeastern United States. Annual Review of Ecology and Systematics 1 1: 387M09. Whitney, G. G. 1994. From Coastal Wilderness to Fruited Plain: A History of Environmental Change in Temperate North America from 1500 to the Present. New York: Cambridge University Press. Edward K. Faison is Ecologist at Highstead in Redding, Connecticut, and David R. Foster is Director of Harvard Forest, Harvard University. Reading Tree Roots for Clues: The Habits of Truffles and Other Ectomycorrhizal Cup Fungi Rosanne Healy H ere's something to ponder: The health and regeneration of grand old oaks ( Quercus ) and majestic pines ( Pinus ) is dependent on the well-being of tiny fungi that associate with the trees' roots. Such small organisms have a big role to play not only for oaks and pines but also for many other trees that rely on their fungal partners to get them through lean and dry times. An estimated 86% of plant species benefit from (or are even depen- dent on) fungal root associates that transfer water and nutrients to the plant in exchange for carbohydrates (Brundrett 2009). Carbohydrates from plants are the result of atmospheric C0 2 (carbon dioxide) fixation through photosynthe- sis and subsequent processes, which the fungi are incapable of doing. The fungal root associates are the mycor- rhizal (myco=fungus / rhiza=root) fungi. They can be roughly sorted into two types based on how they associate with the roots. One type is mostly invisible to us because their hyphae are inside the root (endomycorrhizae), and the other can be seen as a mantle surrounding the root tip (ectomycorrhizae). The endomycorrhi- zal fungi are root associates of the vast majority of herbaceous plants and certain tree species. This article focuses on ectomycorrhizal fungi, which grow mostly in association with trees rather than herbaceous plants. They make their presence known to us not only because we can see them on tree roots hut also because we see their fruiting bodies, particularly from midsum- mer into fall here in New England. Trees such as the red oaks ( Quercus rubra ) and eastern white pines [Pinus strobus) seen here benefit from ectomycorrhizal fungi. The color and "furry" appearance of this ectomycorrhizal red oak root tip are from the fungal symbiont, a Scleroderma fungus. ALL IMAGES BY THE AUTHOR EXCEPT WHERE NOTED NANCY ROSE 34 Arnoldia 72/2 • October 2014 The ectomycorrhizal root tips (top) and fruiting bodies (bottom, at several stages of maturity) of the basidiomy- cete fungus Cortinarius armillatus. Which fungi are they? Thanks to ever more ingenious methods of molecular fingerprinting of fungi, and a grow- ing database of DNA sequences for fungi of all kinds, we now know much more about what species are involved in these relationships. The ectomycorrhizal fungi include some of the largest and most colorful of the fleshy basidio- mycete fungi like Cortinarius and Russula, as well as prized edibles like the king bolete and chanterelle, and deadly poisonous species such as the death cap, Amanita phalloides. Far less is known about the cup fungi that form ecto- mycorrhizae, despite their long history of study. The term "mycorrhiza" was coined by bot- anist Albert Frank in 1885 while he studied the relationship of Tuber, a truffle cup fungus, with its host tree roots in order to determine how to cultivate this gastronomically impor- tant fungus. He and his student, Albert Schli- cht, discovered that the majority of apparently healthy plants that they surveyed in Germany had fungal root associates. Frank was the first to hypothesize that the fungi observed on roots were mutually beneficial with the trees rather than parasitic (Trappe 2005), a hypothesis that has since been borne out by many studies. Most truffles, including the economically and gastronomically important Tuber species that interested Frank, are ectomycorrhizal. I have been studying Pachyphlodes, a common but generally ignored truffle genus, for the past 15 years. During these studies I collaborated with Harvard University Herbaria cup fungus experts Don Pfister and Matthew Smith (now at the University of Florida). We noticed that the asexual form of truffles, termed sporemats here, occur most abundantly on bare or nearly bare soil. This was consistent with reports that fruit- ing bodies of ectomycorrhizal Pezizales (the nomenclatural order for cup fungi) tend to occur in disturbed habitats such as dirt paths or roads in the forest (Petersen 1985). I am now working with Don Pfister to test the hypothesis that ectomycorrhizal Pezizales are more prevalent in managed rather than natural environments. To do this, we are comparing the ectomycorrhi- zal fungi on roots of red oaks (Quercus rubra) in the Arnold Arboretum with those on red oaks in Harvard Forest. A Tale of Two Sites Why choose these two sites for this study? There are some important differences between the Arboretum and the Harvard Forest. The Arboretum habitat is more like a residential area, where much of the understory is kept clear of non-cultivated plant life and the grass is kept short. The soil organic layer is comparatively shallow, and there is not much variety in the litter layer. In contrast, the forests here in New England are characterized by an understory of regenerat- Ectomycorrhizal Cup Fungi 35 Research indicates that the ample foot paths, mowed lawns, and sparse understory in the Arnold Arboretum will favor Pezizales fungi on the root tips of the ectomycorrhizal trees. Sporemats of truffle fungi Pachyphlodes sp. nov. (left) and Tuber sp. nov. (right). An example of a sporemat and the truffle ( Pachyphlodes ligericus ) that its fungal barcod- ln g sequence matches. ing trees, native shrubs, vines, and herbs. The ground under the trees is covered by woody and leafy litter, and under that layer is a deep organic layer composed of roots, soil, and partially broken down organic matter that together form a dense mat that requires a knife to cut through it. Compared to the forest habitat, there is not much in the Arboretum habitat to obstruct the passive transfer of fungal spores produced on the soil sur- face to roots and mycelia in or below the organic layer. This is possibly an important feature for the cup fungi because in order to fruit, the hyphae of outcrossing species such as Tuber must come in contact with a compat- ible mating type nucleus in another hypha. This is in contrast to most ectomycorrhizal basidio- mycete species that form their mycelia with both nuclei soon after germi- nation of their sexual spores. How do com- patible mating types of truffles get together if the mycelia are underground? Perhaps the sporemats on the soil surface play a role m this event. If so, mating may be facili- tated in an environment such as that found in the Arboretum over that found in a forest. 36 Arnoldia 72/2 • October 2014 Ectomycorrhizal basidiomycete fruiting bodies (top) and their root tips (bottom) from (left to right) Amanita rubescens, Craterellus fallax, and Scleroderma areolatum. Let's explore that idea a bit. The sporemats are produced on the soil surface, presumably from the ectomycorrhizal roots below the soil surface. They in turn produce massive numbers of spores that are small, light colored, and thin walled, and therefore probably not designed to function as survival structures. We don't know what their function is, but it makes sense that they might be involved in the mating of truffles and other cup fungi that produce them. With this in mind, as part of the study of ectomycor- rhizal communities, we also collected spore- mats and fruit bodies in the vicinity of the trees we sampled from. Fungus Findings In order to determine what species are on the roots of the trees we sampled, we utilized a technique that yields the nucleotide sequence of the fungus genome from a nuclear region that is known to mutate quickly enough to show differences in nucleotides between species, but not so quickly that they differ much within spe- cies. This region of the genome is not a coding region, and therefore, the mutations have no known impact on reproduction. It is called the internal transcribed spacer region (ITS), and is one of the most useful for studying species lim- its in the fungi. In fact, this region was recently adopted as the first fungal bar code marker in the recently updated International Code of Nomen- clature of algae, fungi and plants (McNeill et al. 2011). There is sufficient data from this genome region available in the National Center for Bio- technology Information (NCBI) that are depos- ited from national and international studies to be able to place most of the sequences from our study within a genus, and in some cases feel confident about the species, or to tell if it is likely an un-named (in NCBI) species. We can also compare our sequences with others in NCBI from a geographic locality perspective, and thus analyze the likely origins of the fungi on the root tips in our study to decide whether they are native or non-native. While our study is not yet complete, I would like to share several interesting vignettes that have come to light. Basidiomycetes were the most frequently sequenced from the root tips in both habitats with 59 molecular taxonomic Ectomyconhizal Cup Fungi 37 This Russula fungus (fruit body and root tip shown) has a sequence that matches root tips in this study, as well as root tips and fruit bodies from a 2006 study by Don Pfister and Sylvia Yang in which they determined that many Russula species are exploited by the Indian pipe plant, Monotropa uniflora. units (MOTUs) from Har- vard Forest and 56 MOTUs from the Arboretum, 17 of which overlapped in both sites. Some MOTUs could be matched to sequences in GenBank from described species or at least sequenced fruit bodies. Russula spe- cies were the most fre- quently sequenced in both habitats with 32 MOTUs. A number of our other sequences matched Russula sequences from a previous study by Don Pfister and Sylvia Yang, but not sequences of any described species. A distant second place for most com- monly sequenced genus was Cortinarius (14 MOTUs) followed by Lactarius [9 MOTUs). Even less common (genus followed by MOTUs within parentheses): Amanita (4), Boletus (1), Byssocorticium (1), Clavulina (4), Craterellus (1) , Entoloma (3), Inocybe (4), Laccaria (1), Pilo- derma (1), Pseudotomentella (1), Scleroderma (2) , Sistotrema (1), Strobilomyces (1), Tomen- tella (7), Trechispora (1), and Tylopilus (1). Nearly equal numbers of Ascomycete MOTUs were sequenced from each site. However, there was little overlap in species. It is particularly interesting that the Pezizales had significantly greater species richness and number of root tips in the Arboretum (10 MOTUs) than in the Forest (3 MOTUs). The cup fungi detected on roots in the Arboretum included Hydnotrya, four species of Pachyphlodes, three species of Tuber, and two root tip sequences that have no match to a fruit body sequence. From Harvard Ectomycorrhizal ascomycete fruiting bodies (above) and their root tips (below) from (left to right) Elaphomyces muricatus, Pachy- phlodes sp. nov., and Tuber separans. oS Arnoldia 72j2 • October 2014 Fruiting bodies of Leotia lubrica, commonly known as jelly babies, were found in Harvard Forest. The researchers sequenced this unusual blue spore- mat, which may be Chromelosporium coerulescens or a related species. The distinctive black ectomycorrhiza of a Cenococ- cum fungus. Forest we detected Leotia lubrica (commonly known as jelly babies) and Elaphomyces (hart's truffle). Cup fungi detected included Tuber sep- arates, and the same species of Tuber (species 46) as found in the Arboretum. We also recovered a sequence that matches that of a lovely blue sporemat for which no fruiting body is known. This sporemat may be Chromelosporium coe- rulescens or a close relative. Cenococcum, an ascomycete not known to make a fruiting body, but with a very characteristic black ectomycor- rhiza was ubiquitous on roots in both habitats. We collected a number of truffle sporemats on the soil surface in the Arboretum, but in Harvard Forest they were found on top of the leaf litter, and even on the lower trunks of trees. Although we know from other ectomycorrhizal root studies that these species colonize roots, few of their sequences were detected on the roots sampled in this study, and none of their fruiting bodies found. The only evidence of their presence using our sampling technique was their sporemats. This may be because the Pezizales tend to be patchy in their coloniza- tion of roots, so they could easily be missed during sampling. The fact that they devel- oped on the surface of the substantial organic layer in the forest shows that the originating mycelium is capable of navigating through the root mat and litter layer from the root tip. Where do the spores from the sporemat go and to what purpose? We don't know. We now see that they are quite capable of being formed atop heavy woodland litter, but we don't know how efficient their dispersal and ultimate journey into the soil is in either a forest or arboretum-like setting. A second mystery came to light when one of the Tuber species detected on roots of a native red oak in the Arboretum was nearly identi- cal in sequence to a species native to Europe, Tuber borchii. To our knowledge, this species has never been detected outside of cultivation in North America. Hannah Zurier, a Harvard undergraduate, received a Microbial Sciences Initiative fellowship to (in part) attempt to reconstruct how this truffle came to reside in the Arnold Arboretum. She found the truffle Ectomycorrhizal Cup Fungi 39 The fruiting body and root tips of the newly named Tuber arnoldianum. again on the same tree, and is in the process of looking for it on other trees in the vicinity. A third interesting story involves another Tuber species. We detected a species (termed ''species 46" by Tuberaceae expert Gregory Bonito, a mycologist at the Royal Botanic Gar- dens in Melbourne, Australia) on the roots of several trees scattered throughout the Arbore- tum, as well as from one of the trees sampled in Harvard Forest. Our sequences match those for an undescribed species, known previously only from orchid root tips in New York and red oak root tips from an urban area in New Jersey. We were fortunate to recover some fruiting bodies from the Arboretum so that we will now be able to describe this taxon. The Arnold Arboretum staff has chosen the name Tuber arnoldianum for this truffle. While data are still being gathered, enough has been analyzed at this point (985 root tip sequences from 24 trees in each site) that I expect the pattern of Basidiomycete to Peziza- les MOTUs in the two sites to hold up. This pattern continues to support the hypothesis that Pezizales are more prevalent in managed woodland sites such as the Arboretum. We can't be certain of the determining factors for this pattern, but refining the experimental param- eters will help to zero in on those factors that are correlative. The well documented history of each accessioned tree, the ease of access to the rich information regarding Arboretum veg- etation, and the encouragement and support of research by the staff at the Arnold Arbore- tum and Harvard Forest make these sites ideal for helping to resolve some of the outstanding questions regarding the ecology of ectomycor- rhizal cup fungi. References Brundrett, M. C. 2009. Mycorrhizal associations and other means of nutrition of vascular plants: understanding global diversity of host plants by resolving conflicting information and developing reliable means of diagnosis. Plant Soil 320: 37-77. McNeill, J., F. R. Barrie, W. R. Buclc,V. Demoulin, W. Greuter, D. L. Hawksworth, P. S. Herendeen, S. Knapp, K. Marhold, J. Prado, W. F. Prud'homme van Reine, G. F. Smith, J. H. Wiersema, N. J. Turland, eds. 2012. International Code of Nomenclature for algae, fungi, and plants (Melbourne Code), adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011. Regnum Vegetabile 154. Germany: Koeltz Scientific Books. Petersen, P. M. 1985. The ecology of Danish soil inhabiting Pezizales with emphasis on edaphic conditions. Opera Botanica 77: 1-38. Trappe, J. M. 2005. A. B. Frank and mycorrhizae: the challenge to evolutionary and ecologic theory. Mycorrhiza 15: 277-281. Yang, S. and D. H. Pfister. 2006. Monotropa uniflora plants of eastern Massachusetts form mycorrhizae with a diversity of russulacean fungi. Mycologia 98: 535-540. Rosanne Healy is a 2013-2014 Sargent Scholar at the Arnold Arboretum, with matching support from Harvard Forest, and is a post-doctoral researcher with Donald Pfister in the Harvard University Herbaria. The Castor Aralia, Kalopanax septemlobus Kyle Port alopanax is a monotypic genus in Araliaceae, the ginseng family. The lone species, K. septemlobus, is a dominant tree in northeastern Asia (Japan, China, Korea, the Russian Far East) where it is valued for the ethnopharmacology of its plant parts and its tim- ber quality. Across Korea, overuse has threat- ened some wild populations and there are now calls to protect the species. Castor aralia is a large deciduous tree that can grow to nearly 100 feet (about 30 meters) tall and has an average trunk diameter of about 40 inches (about 100 centimeters). Its stems are armed with stout prickles that yield to thick, deeply furrowed bark with age. It has very large (to 14 inches [36 centimeters] in diameter), long- petioled, 5- to 7-lobed leaves that may turn bril- liant greenish yellow in autumn. Castor aralia bears large, wide (to 12 inches [31 centimeters] in diameter) inflorescences with numerous small umbels of white flowers that open in August and September here, providing late season nourish- ment to an assortment of pollinators. Success- ful pollination yields abundant blue-black fruits that are retained into winter. A single castor aralia plant was sent to the Arnold Arboretum in January 1881 by Alphonse Lavallee of Segrez, France. This inaugural specimen was accessioned as Acanthopanax ricinifolium — the species' accepted name at the time — and its accession card states only that it was "disposed of" in 1890. Intrigued by its char- acteristics and determined to cultivate speci- mens in Boston, Arboretum Director Charles Sprague Sargent collected seeds of the species on his first excursion to Japan in 1892. Two plants hailing from this collection thrive in the Arbo- retum today. Sargent's account of castor aralia in Forest Flora of Japan (1894) inspired additional collections, including J. G. Jack's 1905 seed collections at Lake Chuzenji (Chuzenjiko) and Sapporo, Japan. A total of 27 Kalopanax septem- lobus accessions are documented in our curated databases and three plants currently grow in the permanent collections. These handsome specimens grow on the east- ern bank of Rehder Pond (accession 84 1-81 -A) and near the paved summit path on Peters Hill (accession 12453-A and C). The younger speci- men (84 1-81 -A) was received as a seedling in 1981 from the United States National Arbore- tum, originating from seeds they received from China's Nanjing Botanical Garden. Growing without competition, its relatively uniform spread of 43 feet (13.1 meters) and height of 35.1 feet (10.7 meters) is remarkable. This specimen is marvelously tactile as the prickles around its 19.6 inch (49.8 centimeter) diameter trunk can still be felt when pressed. The two largest and oldest castor aralias on the grounds are those from Sargent's 1892 collection in Japan. Speci- men 12453-A is 52 feet (15.8 meters) tall and has an astoundingly broad spread of 77 feet at its widest point; 12453-C is 34.7 feet (10.6 meters) tall and has a spread of 53 feet (16.1 meters). In the July 19, 1923, issue of the Bulletin of Popular Information, Sargent wrote of castor aralia: "It is one of the most interesting trees in the collection and, because it is so unlike other trees of the northern hemisphere it is often said to resemble a tree of the tropics." The Arnold Arboretum subsequently distributed Kalopanax septemlobus seeds and plants to scores of researchers, institutions, nurseries, and hobby- ists across the globe. Most prominently, it was among 10 taxa offered as a "reverse birthday present" in celebration of the Arboretum's cen- tennial in 1972 and was included in institutional articles and listings of the best ornamental trees for the New England area. Enthusiasm for castor aralia has since been tempered, however, as it has shown invasive tendencies in some areas, including the Arbore- tum grounds. Its fruits are readily consumed — and seeds subsequently dispersed — by birds; the Hokkaido Research Center in Japan documented 27 bird species feeding on Kalopanax septemlo- bus fruits across a 22 acre (9 hectare) site. Rec- ognizing that dispersed seeds germinate in high percentages, we removed 7 accessioned castor aralias between 2010 and 2012. In addition, the practice of culling castor aralia seedlings from natural and cultivated areas of the Arboretum was formalized in our 201 1 Landscape Manage- ment Plan. The conservation of taxa reported to be invasive is a topic of ongoing discussion here and at other botanical institutions. For the time being, don't miss the opportunity to study and marvel at a few of North America's oldest castor aralia here on our grounds. Kyle Port is Manager of Plant Records at the Arnold Arboretum. The Magazine of the Arnold Arboretum VOLUME 72 • NUMBER 3 . The Magazine of the Arnold Arboretum VOLUME 72 • NUMBER 3 • 2015 Amoldia (ISSN 0004-2633; USPS 866-100) is published quarterly by the Arnold Arboretum of Harvard University. Periodicals postage paid at Boston, Massachusetts. Subscriptions are $20.00 per calendar year domestic, $25.00 foreign, payable in advance. Remittances may be made in U.S. dollars, by check drawn on a U.S. bank; by international money order; or by Visa, Mastercard, or American Express. Send orders, remittances, requests to purchase back issues, change-of-address notices, and all other subscription-related communica- tions to Circulation Manager, Amoldia, Arnold Arboretum, 125 Arborway, Boston, MA 02130- 3500. Telephone 617.524.1718; fax 617.524.1418; e-mail arnoldia@arnarb.harvard.edu Arnold Arboretum members receive a subscrip- tion to Amoldia as a membership benefit. To become a member or receive more information, please call Wendy Krauss at 617.384.5766 or email wendy_krauss@harvard.edu Postmaster: Send address changes to Amoldia Circulation Manager The Arnold Arboretum 125 Arborway Boston, MA 02130-3500 Nancy Rose, Editor Andy Winther, Designer Editorial Committee Phyllis Andersen Peter Del Tredici Michael S. Dosmann William (Ned) Friedman Kanchi N. Gandhi Copyright © 2015. The President and Fellows of Harvard College CONTENTS 2 Bark: From Abstract Art to Aspirin Eva Begley 14 A Dream Come True Peter Ashton 22 Lighting the Night: The Use of Pitch Pine and Bayberry in Colonial New England Sheila Connor 28 Erable de Montpellier, the Montpellier Maple Katherine Urban-Mead Front cover : The bark of paper birch ( Betula papyrifera) shows the prominent horizontal lenticels characteristic of many birch species. Photo by Paul and Eva Begley. Inside front cover: A coalition of local parks organiza- tions, including the Arboretum, worked with the Boston Parks Department to establish the Boston Park Rangers program in 1982. The program was based on the New York City Urban Park Rangers program, established in 1979; this slide of a New York City ranger was likely used in presentations aimed at rallying community support for the Boston program. Archives of the Arnold Arboretum. Inside back cover: Native to the Mediterranean region, Montpellier maple ( Acer monspessulanum ) is noted for its small, leathery leaves and brightly colored samaras. Photo courtesy of Paulo Rocha Monteiro. Back cover: The unique bark of cork oak ( Quercus suber) is used to make cork stoppers, flooring, and other products. Photo courtesy of Amorim. The ARNOLD ARBORETUM of HARVARD UNIVERSITY ALL IMAGES BY PAUL AND EVA BEGLEY EXCEPT WHERE NOTED In the fading light of dusk, satiny bark curls on a greenleaf manzanita ( Arctostaphylos patula ) take on a purplish sheen. The bark of whitebark pine ( Pinus albicaulis) is much finer- textured than that of most pines and resembles an extreme close-up of an impressionist painting. The trunks of giant sequoias ( Sequoiadendron giganteum ) are protected by thick layers of fibrous, fire-resistant bark. Bark: From Abstract Art to Aspirin Eva Begley T o many people, bark is just the gray or brown stuff that covers tree trunks, but it's actually much more interesting than that. Woody dicotyledons and gymnosperms depend on their bark to keep insects and patho- gens out. Bark also minimizes evaporation of water from trunks and branches. The fire- resistant bark of giant sequoia ( Sequoiadendron giganteum ) grows up to 18 inches [45.7 centi- meters] thick and has allowed some individuals to thrive for more than 3,000 years. Cork oak ( Quercus suber), native to southwestern Europe and northwestern Africa, can also survive forest fires thanks to its thick bark. While functional for the tree, bark can be aesthetically pleasing for us. The bark of some trees shows surprising colors, including green, blue, and orange. It can be rough or smooth, stringy or flaky,- it can peel away in long shreds or curl like chocolate shavings on an elaborate gateau. The textures and patterns in bark may remind you of abstract painting or sculpture, jig- saw puzzle pieces, or an old cable-knit sweater. Bark's charms are sometimes accentuated when festooned with lichens or providing a foothold for epiphytes. Anatomy of a Tree As a tree grows taller and adds more leaves and branches, its weight increases. To support the added weight, the trunk and branches grow in diameter. They do that thanks to a sleeve of almost-forever-young cells called the vascular cambium. During the growing season, these cells divide many times, mainly in a plane par- allel to the surface of the trunk or branch. Cells produced on the inner side of the vascular cam- bium become xylem, which, as so-called sap- wood, conducts water and minerals absorbed by the roots to the rest of the tree, then turns into the strong woody core of the tree — the heartwood, which is usually darker in color Bark 3 Mixture of dead cork cells and older, dead phloem Oldest, dead cork cambium Older, dead cork cambium New, live cork cambium Phloem Botanists usually use the term “bark" to refer to everything outside the vascular cambium: phloem; phloem fibers; the innermost, live cork cambium and all its inner and outer derivatives; and older, dead cork cambia along with whatever else has accumulated outside the live cork cambium. The cork cambium and its products (that is, phellem and phelloderm) are collectively referred to as “periderm." The live, deeper-seated components of the bark are sometimes called "inner bark." than the sapwood. Cells produced on the outer side of the vascular cambium become phloem, which conducts sugars and other carbon-based nutrients throughout the tree. In temperate climates, the xylem and phloem formed early in each growing season usually contain lots of relatively large cells,- cells formed later in the growing season are smaller. As a result, the xylem and phloem are built up of concentric rings, each ring constituting one year's growth. Phloem rarely lasts more than a few years (more on that in a moment). Xylem, however, can last well beyond the life of the tree in the form of standing snags or downed wood, or as lumber in buildings and furniture. Similar processes take place in roots. Once in a while, to keep up with the increas- ing girth of the tree, the cells of the vascular cambium divide in a radial plane. The phloem and most other cells outside the vascular cam- bium, though, have matured and aren't able to keep dividing or enlarging — they get stretched to the breaking point. That triggers the develop- ment of a new layer of squat, dividing cells, the cork cambium or phellogen, usually near the stem's surface. Like the cells of the vascular cambium, those of the cork cambium divide mainly in a plane parallel to the surface. (Inter- estingly, the cork cambium isn't necessarily active at the same time as the vascular cam- bium — the cork cambium seems to function more on an as-needed basis, perhaps in response MB 4 Arnoldia 72/3 • February 2015 Front and side views of the bark of sugar pine ( Pinus lambertiana ). The crevices are deep enough to peer into and see the longitudi- nal arrangement of the bark plates formed by successive cork cambia. to the damage caused by stretching and ruptur- ing of cells around the perimeter of the trunk or branch.) The relatively few new cells formed on the inner side of the cork cambium, collec- tively called the phelloderm, usually stay fairly unspecialized; they may separate a bit, allow- ing some air circulation between them, and in some species they become photosynthetic, col- oring the bark green. Far more new cells are pro- duced on the outer side of the cork cambium; but except in a few aquatic or wetland plants, they stay tightly packed, with no air spaces between them. Unlike animal cells, each plant cell is enclosed by a wall composed primarily of cellulose. As the cell matures, its wall may be reinforced by additional layers of cellulose, or, in most cells in the xylem, by a strong, rigid substance called lignin. In the outer deriva- tives of the cork cambium, the cellulosic wall is lined by layers of a waterproof substance, suberin, sometimes alternating with sheets of waxes or lignin. Eventually, these outer deriva- tives die and their interiors become tiny gas- filled pockets, giving them a squishy feel: they have become phellem, commonly called cork. Of course that isn't the end of the story, because in the meantime the vascular cambium continues increasing the plant's girth. Eventu- Bark 5 ally, that first layer of cork also gets stretched excessively and starts to crack. In cork oak, occasional cell divisions in a radial plane allow the cork cambium to keep pace with the growth in girth, but more commonly the first-formed cork cambium dies and new cork cambium forms deeper in the trunk or branch, sometimes even in the outer, older part of the phloem. In some species, each new cork cambium forms a complete sleeve,- other species produce many small, overlapping patches of cork cambium, a bit like curling shingles on an old roof. Often, these later cork cambia are initiated right underneath cracks in the tree's surface, like internal bandages, ensuring that no crack gets deep enough to damage the living interior of the tree. This process is repeated over and over throughout the life of the plant. Eventually, a complex structure is formed, with everything outside the innermost, most recently formed cork cambium either dead or dying. The bark of lacebark elm ( Ulnms parvifolia) has a jigsaw-puzzle-like pattern. Bark Variations The texture of the bark depends largely on the shape and location of successive cork cambia and on the types of cells "trapped" between them. Chinese or lacebark elm ( Ulmus par- vifolia), for example, has many overlapping, irregularly shaped cork cambia fairly close to the surface. Trees with deeper-seated cork cam- bia have rougher, craggier bark, like northern red oak (Quercus rubra) and tulip tree ( Lirio - dendron tulipifera). Layers of thin-walled cells, whether the inner derivatives of the cork cambium or part of the phloem, are structur- ally weak, so bark characterized by such lay- ers is likely to flake or peel off easily. Phloem sometimes contains lots of long, skinny, thick- walled but pliable cells, called fibers,- as old phloem gets incorporated into the bark, these fibers give it a stringy texture. In some pines, the outer derivatives of the cork cambium con- sist of alternating bands of suberized cork cells This Garry oak, also known as Oregon white oak ( Quer- cus garrayana ), has deeply creviced bark. 6 Arnoldia 72/3 • February 2015 The bright green bark of palo verde ( Cercidium flori- duiri), a member of the legume family (Fabaceae), can be quite variably patterned; this particular tree shows kite-like shapes. and short, heavily lignified cells, called stone cells, that harden the bark. Layers of dead, waterproof cells are fine for protecting trees from bugs, desiccation, and other dangers, but they also hinder gas exchange. Like most living things, the live cells inside trunks and branches, including those of the vascular cambium and phloem, need oxygen. Lenticels provide the solution. They are small patches of loosely packed cells with lots of air spaces between them that the cork cambium produces here and there instead of dense arrays of cork cells. In some species, the lenticels are hidden at the bottom of cracks in the hark; in others, such as paper birch ( Betula papyrifera), they form a prominent and characteristic part of the bark's appearance. Gases diffuse in and out through the lenticel's air spaces, allowing the live interior parts of the trunk to "breathe." Also, any green, chlorophyll-containing cells in the bark produce oxygen as a byproduct of pho- River birch ( Betula nigra ) is admired for its multicol- ored, dramatically peeling bark. Close examination reveals that each papery sheet is covered with the long transverse lenticels often found in the genus. tosynthesis. That oxygen gets snapped up by nearby, live, non-photosynthetic cells, which give off carbon dioxide, which their photo- synthetic neighbors then use to produce more sugars — as neat a solution as any recycling sys- tem devised by engineers. Different species of the same genus can have very different bark colors and patterns. Take the birches, for example. Sweet birch ( B . lenta) has rather ordinary-looking gray hark, but paper birch and European white birch ( Betula pen- dula ) have smooth white bark with long, trans- verse lenticels. The lenticels of western water birch ( B . occidentalis) form a similar pattern against a beautifully shiny, pinkish brown back- ground, while in yellow birch ( B . alleghanien- sis) the background is yellowish brown or dark gray. River birch ( B . nigra) is often grown for the tan, reddish brown, and dark gray sheets of hark that peel off its trunk in shaggy disarray. The maples are even more varied. Many have NANCY ROSE Bark 7 bark that is plain gray in color, albeit with vari- ous textures. But then there's the aptly named paperbark maple (Acer griseum) with peeling sheets of cinnamon colored bark, Father David's maple (A. davidii) with its characteristic ver- tical white squiggles on a bright green back- ground, and coral bark maple (A. palmatum 'Sango-kaku'), a Japanese maple that adds color to winter gardens with its brilliant red branches. Bark's appearance often changes with age, and it's common for the bark of twigs and young branches to differ from that of older limbs. An extreme example is European white birch, in which the rough, gray to almost black bark near the base of the trunk forms a stark contrast to the creamy white bark higher up. And in aspen ( Populus tremuloides), wherever the trunk has been wounded, be it by fungal attack, natural Younger branches of coral bark maple ( Acer palmatum 'Sango- kaku') are bright red. abscission of the lower branches as the tree gets taller, a bear climbing the tree, or lonely sheep- herders or bored teenagers carving their names into the tree, the bark becomes black and fis- sured, very different from the tree's normally smooth, pale bark. Bark Beneficiaries Thick bark has some obvious benefits to trees, but the cracks and fissures in that bark can also provide good habitat for other species. Especially on rough-barked trees, enough soil, organic debris, and moisture can collect to fill minute pockets in which lichens, mosses, and larger epiphytes such as ferns and orchids can get a toehold. Often, different species of lichens and mosses grow on the upper and lower sur- faces of leaning tree trunks and large limbs. Black bears have left permanent calling cards on the trunks of this quaking aspens ( Populus tremuloides). 8 Arnoldia 72/3 • February 2015 The bark on the upper part of these old red fir ( Abies magnified) trunks is almost hidden by wolf lichen ( Letharia spp.); the lichens don't grow below the average snow line in the grove. Some mosses and lichens may prefer certain species of trees; for example, in the northern Sierra Nevada mountains, wolf lichen ( Letharia spp.) usually seems to grow more luxuriantly on the trunks of red fir ( Abies magnified ) and incense cedar [Calocedrus decurrens ) than on the trunks of nearby seemingly equally rough-barked pines, though, the pines' branches sometimes bear dense chartreuse masses of this lichen. Insects use the cracks and fissures in bark as places to hide,- some feed on bark; others lay their eggs on or under the bark of dead or dying trees or trees stressed by drought. Col- lectively, these insects and their larvae provide a smorgasbord for insectivorous birds such as nuthatches, creepers, and woodpeckers. Sap- suckers [Sphyrapicus spp.), also members of the woodpecker family, drill horizontal rows of holes into the trunks of favorite tree species to feed on the nutritious inner bark and the sap that oozes out, along with insects caught in the flow. Subsequently, other woodpeckers, orioles, hummingbirds, warblers, and even some insects and mammals feed at these "sapsucker wells. ,, Nuthatches ( Sitta spp.), gray jays ( Perisoreus canadensis), and some species of woodpeck- ers cache nuts, seeds, and even dead insects by thrusting them into bark crevices, but acorn woodpeckers ( Melanerpes formicivorus), native to the western United States and parts of Mexico, have raised the art of food storage to a new level. These social birds typically live in families of two to a dozen or more animals, and each family creates a communal acorn larder in the bark of thick-barked living trees, the bark or wood of standing snags, and even util- ity poles and fence posts. Acorns are stored in individual cubbyholes, each of which takes a total of about an hour to make although it's rarely finished in one sitting; typically, family members take turns drilling it over a period of a few days. A "granary tree" may have anywhere Bark 9 Sapsuckers drilled multiple rows of holes in this white alder ( Alnus rhombifolia). Extensive sapsucker drilling may partially girdle trees, which can eventually lead to the tree's decline. from one or two thousand to tens of thousands of acorn-sized cubbies, and each year the birds drill many more holes to replace those lost as limbs break off and old trees fall. In fall, the birds harvest ripe acorns from the branches of nearby oak trees (they rarely collect acorns that have already fallen to the ground), pry off the caps, and hammer the acorns into the pre- drilled holes. The flat end of the acorn, which provides a better surface for hammering, is almost always on the outside. If the first hole is too large or too small, the bird will try other holes until it finds one that is just the right size for a snug fit. The acorns provide an impor- tant food source for the family throughout the winter and early spring. Contrary to earlier belief, it seems that the birds feed directly on the acorns, not just on the insect larvae that sometimes infest them. Acorn woodpeckers constructed a granary in this valley oak ( Quercus lobata ). The tree is now dead, but the presence of a few remaining slabs of bark full of the distinctive holes indi- cates that the birds started their work while the tree was still alive or at least still had bark on it. Some mammals feed directly on bark. Por- cupines and snowshoe hares like conifer bark. Moose will eat bark in winter if nothing more to their liking is available. Beavers, on the other hand, love bark, especially aspen (which is abominably bitter to human taste buds), but also other Populus species, willows ( Salix spp.), birch, red-osier dogwood ( Cornus sericea), and other species. I've even seen conifers (specifi- cally, lodgepole pine, Pinus contorta subsp. munayana ) felled by beavers. During the grow- ing season, the animals eat the buds, leaves, and twigs of these plants as well as the bark. In winter, bark is their primary food. Since bea- vers can't climb trees to reach the goodies up in the canopy, their solution is to gnaw down the entire tree. They are amazingly efficient at this: I once watched a beaver scramble out of an Ozark river and up a steep bank to a young 10 Arnoldia 72/3 • February 2015 Acorn woodpeckers drilled holes for various acorn sizes in this blue oak ( Quercus douglasii). maple, with a trunk diameter of maybe 4 to 5 inches (10 to 13 centimeters). Within moments the tree's crown was swaying wildly, and in less than five minutes the heaver had dragged the entire tree through thick undergrowth back into the water and was swimming away with it. The animals don't waste much: debarked trunks and branches are used to construct or reinforce the beavers' lodges and the dams that they are famous (or notorious, depending on your point of view) for building. And wherever winters are typically cold enough for ponds to freeze over, heaver families cache enough young branches each fall to last them through the win- ter, usually by jamming the butt ends deep into the mud at the bottom of the pond, sometimes by building floating rafts, placing already peeled logs and less-preferred foods such as alder on top of the raft and favorites like aspen and wil- low below so that the branches are easily acces- sible from underwater. Canoes, Quinine, and Corks Bark benefits people too. Leafing through Dan- iel Moerman's encyclopedic Native American Ethnobotany, I get the impression that Native Americans found the bark of just about every native tree species useful in some way, be it medicinally or to make baskets and other con- tainers, rope, cloth, dyes, and many more items. In winter, the Lakota, Blackfoot, and Cheyenne fed their horses with cottonwood and aspen bark. Some tribes used slabs of bark as roof- ing material. In the upper Midwest the Ojibwe (also known as the Chippewa) stitched sheets of paper birch bark together with spruce roots Beavers leave tell-tale signs wherever they fell trees. Bark 1 1 i j >&j 1 ■ The bark of cork oak ( Quercus suber ) is carefully hand-harvested. The bark regrows and can be harvested again in about ten years. to waterproof their homes. In fact, so versatile is the bark of paper birch that it was used for everything from canoes to kitchen funnels; as Moerman puts it, "Nearly any kitchen utensil common to the white man could be duplicated in birch bark by the Ojibwe." The homes and barns of North America's European settlers were often roofed with the bark of American chestnut ( Castanea den- tata). Some of those buildings might have been painted using brushes made by boiling bass- wood ( Tilia americana ) bark in lye, then pound- ing it to extract its hemp-like fibers, a technique the settlers learned from Native Americans who made rope, sewing thread, and woven hags from basswood bark. The settlers probably wore shoes made of leather processed with tannins extracted from hemlock or oak hark, and some of their clothes may have been dyed with quer- citron, derived from the yellow-orange inner hark of the black oak [Quercus velutina). Alone or in combination with mordants or other dyes, quercitron can yield colors ranging from bright yellow to warm browns. It was used commer- cially until well into the twentieth century, when cheaper synthetic dyes were discovered. Human health has also henefitted from cer- tain chemical compounds in bark. To limit being incessantly munched by herbivores and damaged by insects, some plants produce chem- ical defenses. Some of these defenses are sim- ply metabolic by-products, such as the calcium oxalate crystals that render the bark of some pines unpalatable to browsers. Others, such as various alkaloids, tannins, and cyanogens (which give cherry bark its distinctive bitter almond scent and cough-suppressing proper- ties), require greater metabolic input and their synthesis consumes nutrients, but they pro- vide valuable protection to long-lived plants. It's these same compounds that make the bark of some species medically useful. COURTESY OF AMORIM AND APCOR (PORTUGUESE CORK ASSOCIATION! 12 Arnoldia 1213 • February 2015 Two of the most famous drugs we owe to bark are aspirin and quinine. The Greeks used wil- low bark extracts as long as 2,400 years ago to relieve pain,- similarly, many Native American tribes used willow bark to treat colds, fevers, and headaches. In 1827, a French chemist, Henri Leroux, isolated a compound he called salicin from willow bark; a related compound, salicylic acid, was discovered in 1839. Both compounds, though, cause nausea and gastric pain, and chemists continued searching for an effective pain reliever. Another related com- pound, acetylsalicylic acid, was discovered in 1853, but it wasn't until 1899 that its pharma- ceutical value was recognized and the Bayer Company began marketing it as aspirin. Quinine and other anti- malarial alkaloids are derived from the bark of several species of Cin- chona, native to the Andes and related to coffee. There are conflicting accounts of how Cinchona trees reached the Old World. In the nine- teenth century, both the English and the Dutch tried to smuggle seeds or seed- lings out of South America, where the quinine trade was tightly controlled. Eventu- ally the Dutch established large Cinchona plantations on Java, and through breed- ing and selection increased the bark's alkaloid yield from 7% to 17%. Today other drugs are available, but the microscopic proto- zoan that causes the disease is becoming resistant to many of them, and millions of people are still affected by malaria annually. To conclude on a happier note, though, where would we be today without the cork oak, whose thick outer bark is used to make flooring, fishing rod handles, wood- wind instrument joints, and wine bottle corks by the bil- lion? People have used cork at least since Roman times: Pliny the Elder, writing in the first century A.D., listed fishing floats, women's win- ter shoes, and stoppers for Like many of the 60 or so species of manzanita ( Arctostaphylos ), this one (species unknown) displays eye-catching bark. Bark 13 wine jars among its uses. It takes a cork oak tree 25 to 40 years to build up a layer of cork thick enough to harvest, but the first harvest consists of hard, crumbly material good only for bulletin boards and insulation. If the cork is removed carefully, a new phellogen devel- ops in the phloem 25 to 35 days later. The tree resumes cork production and can he harvested again 9 or 10 years later. Not until the third harvest, however, is the cork of sufficient qual- ity for wine stoppers. The trees typically live 250 to 350 years, so each tree can be harvested many times. The practice of harvesting bark in cork oak forests actually helps preserve this unique ecosystem from land development so many conservation organizations promote the use of natural cork. And even though oenologi- cal research suggests that it doesn't really make much difference whether wine is sealed with natural cork, synthetic stoppers, or screw caps, yanking a plastic stopper out of a bottle just doesn't provide the same sort of tactile pleasure that pulling a real cork does. So pull a real cork, pour a glass, and drink a toast to bark. Further Reading Bugalho, M. N., M. C. Caldeira, J. S. Pereira, J. Aronson, and J. G. Pausas. 2011. Mediterranean cork oak savannas require human use to sustain biodiversity and ecosystem services. Frontiers in Ecology and the Environment 9: 278-286. Costa, A., H. Pereira, and A. Oliveira. 2003. Variability of radial growth in cork oak adult trees under cork production. Forest Ecology and Management 175: 239-246. Cutter, E. 1978. Plant Anatomy. Part 1: Cells and Tissues, 2nd edition. Reading, Massachusetts: Addison- Wesley Publishing Company. Elphick, C., J. Dunning, and D. Sibley. 2001. The Sibley Guide to Bird Life and Behavior. New York: Alfred A. Knopf. Esau, K. 1965. Plant Anatomy, 2nd edition. New York: John Wiley and Sons. Esau, K. 1977. Anatomy of Seed Plants, 2nd edition. New York: John Wiley and Sons. Heinrich, B. 2003. Winter World: the Ingenuity of Animal Survival. New Yorlc: Harper Perennial. Howard, E. T. 1971. Bark structure of the southern pines. Wood Science 3(3): 136-138. Kaufert, F. 1937. Factors influencing the formation of periderm in aspen. American Journal of Botany 24(1): 24-30. Kwiatkowsky, M. J., J. K. Skouroumounis, K. A. Lattey, and E. J. Waters. 2007. The impact of closures, including screw cap with three different headspace volumes, on the composition, colour, and sensory properties of a cabernet sauvignon wine during two years' storage. Australian Journal of Grape and Wine Research 13: 81-94. Lanner, R. M. 1999. Conifers of California. Los Olivos, California: Cachuma Press. Moerman, D. E. 1998. Native American Ethnobotany. Portland, Oregon: Timber Press. Moreira, F., I. Duarte, F. Catry, and V. Acacio. 2007. Cork extraction as a key factor determining post- fire cork oak survival in a mountain region of southern Portugal. Forest Ecology and Management 253: 30-37. Pereira, H. and M. Tome. 2004. Cork oak. In: J. Burley et al., eds. Encyclopedia of Forest Sciences. Oxford, UK: Elsevier, pp 613-620. Pliny the Elder. Translated by J. F. Healy. 1991. Natural History: a Selection. London: Penguin Books. Rupp, R. 1990. Red Oaks and Black Birches: the Science and Lore of Trees. Pownal, Vermont: Storey Communications. Schery, R. W. 1952. Plants for Man. Englewood Cliffs, New Jersey: Prentice-Hall,. Silva, S. P., M. A. Sabino, E. M. Fernandes, V. M. Correlo, L. F. Boesel, and R. L. Reis. 2005. Cork: properties, capabilities, and applications. International Materials Reviews 50(6): 345-365. Stevens, K. J., R. L. Peterson, and R. J. Reader. 2002. The aerenchymatous phellem of Lythrum salicaria L.: a pathway for gas transport and its role in flood tolerance. Annals of Botany 89: 621-625. Vander Wall, S. B. 1990. Food Hoarding in Animals. Chicago: University of Chicago Press. Waisel, Y., N. Liphschitz, and T. Arzee. 1967. Phellogen activity in Robinia pseudoacacia L. New Phytologist 66: 331-335. Zeiner, D. C. et al. 1990. California’s Wildlife : Volume III — Mammals. State of California, Department of Fish and Game. Eva Begley, Ph.D., is a botanist and retired environmental planner who has worked in academia, private industry, and government. She lives in Sacramento, California. A Dream Come True Peter Ashton T he possibility of being appointed director of the Arnold Arboretum in 1978 had come as a considerable surprise, but I jumped at it. Ever since my first professional appointment in 1962 as forest botanist in the Sultan of Brunei's government, I had been send- ing plant specimens to the Arnold as one of the six leading botanical research institutions both within and outside the Far East that special- ize in the flora of East Asia, tropical as well as temperate. I respected the Arnold's scientific reputation in large part because of former Arbo- retum director Elmer Drew Merrill's astonish- ing achievements on the flora of the Philippines and southern China. Arboretum notables Ernest Wilson and Alfred Rehder were also well known to me and, as a life-long gardener and amateur horticulturist, the Arboretum's unique design by Frederick Law Olmsted intrigued me. Mary, my wife, and I will never forget our first glimpse of the Arboretum. During my interview, I sensed unhappiness among staff; morale was low. Mary was asked why she would wish to leave Scotland and her sheep; "Why on earth do you wish to come to this place?" quizzed another. Even the housekeeper in the fine old guesthouse at the faculty club, where we were accommodated on the Harvard campus, expressed the same feelings, and the (somewhat mythical) view that the Boston area had a crime level unimaginable in Aberdeen. When I arrived, curation and the living col- lections policies bore the mark of the celebrated horticulturist Donald Wyman who had been at the Arboretum from his appointment by tropical systematic botanist and director Elmer Drew Merrill in 1935 until his retirement in 1970. Wyman's interest had been in ornamen- tal horticulture, reflected in his book Wyman’s Gardening Encyclopedia, still the most com- prehensive text specifically designed for Ameri- can gardeners. The Arboretum then, as now, continued to sustain the keen interest and sup- port of many members of the Garden Club of America and the Federation of Garden Clubs, as well as the ornamental nursery industry. But I was skeptical that Harvard and its upper administration really understood its fundamen- tal scientific importance, nor the importance of its potential role within the university. Indeed, only one director following Charles Sprague Sargent, Karl Sax, had used the living collec- tions in his research. But research universities focus on endeav- ors that advance scientific theory. The Arbo- retum's global herbarium collection, and with it the systematic botanists, had been removed to Harvard campus in Cambridge in the 1950s on the recommendation of a review chaired by Professor Irving H. Bailey. That decision alone led to nearly a decade of litigation between the University and the Association of the Arnold Arboretum, Inc. Harvard's adjacent Bussey Institute for plant research finally closed near that time, its distinguished faculty, scholars and researchers having been relocated to Cam- bridge two decades earlier in the 1930s. The Arnold Arboretum had become a backwater for the University, indeed "an orphan institu- tion" within the broad missions of the Univer- sity to educate and discover. Among faculty, Carroll Wood was alone in running a course based on the collections by our time, though Peter Stevens also used them later. Around the time I assumed my position, the Jamaica Plain-West Roxbury neighborhoods had been experiencing long decline, and this, too, had impacted the Arboretum. Trash col- lection had become a major activity for grounds staff, kids periodically drove beat-up automo- biles off the summit of Peters Hill, while two corpses were discovered in our first year, one head-first down a road drain. So, there was no shortage of challenges, but that gave the job particular interest! Once I accepted this challenging position, it became my goal to reinvigorate the research functions of the living collections of the Arbo- ALL IMAGES FROM THE ARCHIVES OF THE ARNOLD ARBORETUM Peter Ashton 15 Peter Ashton in the greenhouse, 1983. Given the pristine appearance of the Arboretum today, it's hard to believe that it was once plagued by litterbugs and vandals. The photo above shows a trash-strewn slope in the Conifer Collection in 1973. return. Colleagues in Cambridge had to be convinced that a systematic col- lection of specimen trees could be a resource for cutting-edge research. But first the living collections themselves had to be reviewed, and a new cura- torial policy defined and executed, before a convincing case could be made. Because Sargent, on advice from Asa Gray, one of the world's leading botanists in his time, had established a systematic collection of woody plants, carefully selected and documented, the key was to bring this founding vision back to the fore. As I soon discovered, the Arboretum could then assume a unique role among gar- dens in Boston that complemented Boston's other two great living botani- cal and horticultural gardens: Mount Auburn Cemetery, a horticultural landscape focused on trees,- and the Garden in the Woods, a native wild- flower garden. Together, these three wonderful botanical collections could together offer the public a diversity of plants unequaled anywhere else in the New World, and in very few other places elsewhere. I realized that our collective objective should be to com- plement, rather than compete. My first quest, therefore, was to see the original Olmsted road plan and planting scheme. As Sargent had intended, the collections were laid out in such a way that a visitor could observe the families of trees hardy in the climate of Roxbury "with- out alighting from his carriage." On inquiry, I discovered that the Arbo- retum library did not have the plans, nor was it clear where they could be found! But the old Olmsted firm buildings and archives still existed at Fairsted in Brookline, thanks to the interest and commitment of the land- scape architect Joe Hudaclc. Arbore- tum archivist Sheila Connor spent a fortnight searching for the original plans in a garage full of Olmsted's 16 Arnoldia 72/3 • February 2015 teenth century, to decorate garden space and to ornament domestic architecture. John Claudius Loudon, in England, was the leader, adorning colorful but often fussy gardens with masonry in formal classical mode while, by the end of the century William Robinson was promoting mythical bucolic utopia in elaborate pastiches. But Olmsted returned to those more serene and unified landscapes, when the whiggish English aristocracy of the eighteenth century could afford to create scenes recalling Claude Lorraine's paintings, and of sufficient scale for architecture to be subordinate to nature. Perhaps significantly, these potentates were against the king and often much in sympathy, politically as well as esthetically, with the American project (did you know that Thomas Hollis, whose name is commemorated in the Harvard library system, Hollis House, and the town of Holliston, was a landowner here in Somerset, England, and a major Harvard benefactor who never visited America?). The foremost proponent of their mythical land- scapes, Lancelot "Capability" Brown, used mass plantings of native trees to sculpt his spaces with only the occasional exotic as punctuation. Olmsted was in that spirit and I was empathetic, having been at a high school set in one of Brown's creations. That was the time when Sar- gent, Gifford Pinchot, and their colleagues were instigating the first systematic survey of the American tree flora, gauging the extent of America's forests and revealing the enormous diversity of native trees and their potential for parks and gardens — in com- parison to England's rather paltry thirty-five native tree species. Olmsted, although responsible for the plan of Biltmore and other great American private estates in the Brown tradition, was primar- original works,- she found them and retrieved them for copying. Only later, Fairsted became a National Historic Site, while the original plans are now in the Library of Congress. One must recall how revolutionary Olmsted's landscape philosophy was in the late nineteenth century. This was the time when leafy suburbs started to expand on a grand scale, when a new industrial urban rich could express their fan- tasies in ornate gardens. A vast array of plant introductions from other regions of similar climate had become available during the nine- Arboretum visitors near Bussey Brook in the early 1970s. Peter Ashton 17 ily focused on bringing an appreciation of natural land- scapes to the general public in city parks, university cam- puses, and m his involvement with the growing conserva- tion movement. Harking hack to Capability Brown, he exploited the majestic spaces of the new continent includ- ing the growing cities, and achieved what was unachiev- able in crowded Europe. This accomplishment can still be admired and cherished in Boston's Emerald Necklace. Olmsted's Arboretum plans revealed how he seamlessly combined his philosophy of landscape design with the „ ^ . . ... 1 ° Peter Ashton in his requirements of a systematic botanical collection. Bearing in mind that trees within genera and even families share much architecture in common, groves of tree fami- lies, rather than species, can achieve a similar effect in the landscape. But cultivars selected for outstanding color or shape must he used with utmost discretion. Thus it became clear that the Olmsted- Sargent design and planting plan not only pro- vided an optimal solution to the design of an arboretum whose purpose was both to provide a representative systematic collection for sys- tematic and comparative research, but it is a historic landscape for designers and planners: a park within which the public can both recreate and learn. I realized that such a project remained unique. The Royal Botanic Gardens, Kew, are a historic landscape, but their land is uncom- promisingly flat, denying the curving sweep of Olmsted's contour-hugging roads at the Arnold. Neither did Kew start with a clear accession plan. The aim at the Arnold, to introduce at least three provenances of each taxon, to record location of collection, and to ensure nomencla- tural verification with an herbarium voucher, is known to me in only one other great nine- teenth century botanical garden, Buitenzorg, which was originally established by the Dutch as an ornamental garden around the palace of office at the Arboretum, 1983. their governor-general of the East Indies. Mod- eled after the king of Prussia's garden Sans Souci ("carefree"), Buitenzorg was set in Bogor, the town that was built as the colonial administra- tive center on the island of Java. The gardens were reorganized and landscaped under Stam- ford Raffles, founder of Singapore, who, in his twenties, governed the Dutch East Indies for the British who had expropriated them during the Napoleonic wars. The gardens became a scien- tific establishment thereafter, while remaining a public park. For me, with a decade in Borneo at the start of my career, the plant explorations of Sargent and Engelmann west of the Mississippi River recalled the great Johannes Teijsmann. Thanks to his intrepid explorations of Borneo and Sumatra in leech-gorged clogs, the Buiten- zorg gardens (now the National Botanic Gardens of Indonesia) hold the world's greatest collec- tion of tropical woody plants. From the outset they too had been meticulously documented and curated. And they are beautiful to look at, though nothing compared to the Arboretum! And they have had a research laboratory on their grounds for over a century (though they, too, recently had their herbarium moved to Jakarta by unthinking biological policy-makers). My prime objective, of returning the Arbo- retum to the fold of great research institutions 18 Arnoldia 72/3 • February 2015 within a research university, had therefore to be to review collections policy, and especially to redefine accessions policy. This was admirably accomplished under horticultural taxonomist Stephen Spongberg's leadership. This resurgence also called for enhanced documentation and ver- ification of the living collections. To accomplish this, with National Science Foundation fund- ing, herbarium vouchers were obtained, afresh or for the first time, from all established living collections and sent to taxonomic authorities for verification. That project was led by David Michener, who had little difficulty in attracting a burgeoning team of enthusiastic volunteers. And collections documentation and manage- ment was computerized: BG-BASE was intro- duced by its creator, Kerry Walter, who had come with the fledgling Center for Plant Conservation to whom we had offered the Hunnewell Build- ing attic, at that time unreconstructed. This critical and widely used database system was based on the Arboretum's documentation and workflows, and the Arboretum became the very first user of BG-BASE. Since then, these pio- neering efforts in curation and collections man- agement have been enhanced to bear the fruits that represent the Arboretum's current superb program led by Curator of Living Collections Michael Dosmann. The program of public education, which expanded as membership in the Friends of the Arnold Arboretum had grown, was awarded a major grant to initiate a schools program, including a botany and interpretation program for teachers. In the meantime, we were reach- ing out to local communities, and to the West Roxbury police who received a Christmas cake from my unstoppable and persuasive Mary. This worked with such effect that officers on horseback soon appeared. And a crash campaign against trash resulted in a dramatic response from the public and less work for grounds staff. Meanwhile the gentrification of Jamaica Plain, Roslindale, and West Roxbury, which was to utterly change community interest in the Arboretum, was starting. Thanks also to Mary's involvement with our vol- unteers, a support group, the Arboretum Associates, was formed. The group success- fully raised funds for a variety of Arboretum projects that had heretofore been on the back burner. The annual plant give- away and plant sale became a major event thanks to the support gained by the Associ- ates among leading nurseries. For instance, an accompanying auction attracted media atten- tion: Bids came from as far as Paris, and a yellow-flowered Clivia went for a princely $2,000! But returning active funda- mental research to the living collections remained an unre- solved challenge. Harvard is a "guided democracy." The heart and soul of Harvard is the Fac- ulty of Arts and Sciences (FAS). All academic policy, including The late 1970s and early 1980s saw an upswing in violence and vandalism in Boston, which led to a subsequent drop-off in visitation to city parks. In response, the Arboretum collaborated with several parks associations and the Boston Parks Department to create the Boston Park Rangers program, with the goal of increasing safety and visitorship. Seen here, mounted Park Rangers interact with Arboretum visitors along Meadow Road in 1983. Peter Ashton 19 Peter Ashton (center, seated) at a meeting in front of the Hunnewell Building, 1982. faculty appointments, rests with the faculty themselves. The university's schools have their own faculty and policies. But the allied institutions, such as the Arnold Arboretum, are in a no-man's land in which respon- sibility for faculty and research appointments has changed from time to time. Those allied institutions that are recognized as essential assets for FAS aca- demic departments were in the best position, for their appoint- ment priorities coincide. But the director of the Arnold Arbore- tum, clarified by the lawsuit of the fifties, reported directly to the university's president. Derek Bole, president at that time, was Peter and Mary Ashton in 1988 20 Arnoldia 72/3 • February 2015 determined to bring the directors of Harvard's rich panoply of allied institutions, who under- standably were perceived as unfettered oli- garchs, under appropriate authority within FAS. This intent was particularly desirable in plant science, which was and still is fragmented under several institutions, each with its own endowment: four herbaria (the Arnold Arbo- retum, Gray, Ames, and Farlow), the Botani- cal Museum, Harvard Forest, and the Arnold Arboretum. Only in the case of the Arboretum is there a legal constraint on subsum- ing the institution within the program of an academic depart- ment — and only the Arbo- retum possessed a sufficient and substantial endowment. President Bok insisted that all research appointments, both curatorial and faculty, receive the support of the faculty of that academic department whose mission was closest to the Arboretum's, in this case, Organismic and Evolutionary Biology (OEB). This at once orphaned the applied research in horticulture and forestry for which the Arboretum had built a distinguished reputation. The Museum of Comparative Zoology (MCZ) had an invaluable research and pedagogic relationship with Harvard's school of applied zoology: the Medical School. But there has been no botanical equivalent at Harvard since the Harvard Forest's program in forestry ceased in 1931. Research appointments at the Arboretum were then exclusively in the field of systematic botany (taxonomy), at that time no longer at the cutting edge of theory as in Sargent's day, although there was about to be a renaissance thanks to advances in molecular genetics. Research was confined to the herbar- ium, which had been amalgamated with other herbaria in Cambridge. I saw limitless opportunities for exciting new comparative research that would avail of a systematic collection of living trees, but colleagues in the Arboretum and OEB were unconvinced, skeptical whether candidates of stature could be found. Thanks in large part to the support of Professor Lawrence Bogorad, who chaired the committee of directors of bio- logical institutions at that time, I was able to initiate a search for a junior faculty appoint- ment on the Arboretum staff, in root biol- ogy. Bogorad happened to be a distinguished colleague in a different department, Cellular and Developmental Biology. John Emset was appointed, and a modest lab set up for him in the Dana Greenhouses headhouse. His work, on the evolution and systematics of hormonal response to root initiation, was pathbreaking and of both theoretical interest and practi- cal application. Besides, he had the friendly and sympathetic personality that made him a superb instructor and a star among our volun- teers and Friends. But Emset did not succeed in gaining tenure, and opinion hardened against my experiment. Most difficult, I was convinced that no research program would flourish at the Arboretum without a good field laboratory, which would allow fresh plant material from the living collections to be brought in at once for study and experiment. Peter and Mary Ashton at the Arboretum for a reception to honor Peter's receipt of the prestigious Japan Prize in 2007. Peter Ashton 21 Without researchers on the staff who wished to avail of a laboratory, I sought to attract the interest of faculty in the several plant science departments in the universities of the Boston region. Thanks to some beneficent friends of the Arboretum, funds had been promised for construction of a modest lab. But new labora- tories are normally approved at Harvard only where there is a potential or existing faculty to attract to them, or where a group of existing fac- ulty campaign for one. Unfortunately, my own research in tropical tree biology could hardly be said to avail of our temperate living collections. Had I depended on the living collections in Jamaica Plain and Roslindale, a case could have been made as a condition of my appointment. Instead, a conclusion was reached at a meeting of the OEB Visiting Committee in 1988 that the Arnold Arboretum should retain a separate existence from the department and therefore FAS, and that no strong case therefore existed for faculty appointments on its staff. Lawrence Bogorad, a past president of the American Association for the Advancement of Science, alone continued to support my viewpoint: It was clearly time for someone more suitably placed to take up the challenge. Eddy Sullivan, educator and at that time vice-mayor in the City of Boston's mayor Kevin White's govern- ment, who had become a staunch supporter in my negotiations with the city, quipped, "You don't have to worry, Peter,- if it all fails, you can always go home to Ireland"! Seen in this setting, it was no surprise that my successor as Arboretum director, Bob Cook, was not initially optimistic about the prospects of my case to embed the university's research back into the Arboretum. Bob had come from directing Cornell Plantations, which enjoyed a successful research and pedagogic relation- ship with academic departments in one of the leading universities in both fundamental and applied agricultural research. In the expected way, he arrived with a new broom. It was not long, though, before he came to realize the importance, even if against all odds, for build- ing a laboratory at the living collections if they were to stand any chance of returning to Harvard's academic fold. Freed of faculty influ- ence as he was by the Arboretum's detachment from FAS, it is to Bob's great credit that with dogged determination he gained the support of the president's representatives in the adminis- tration. Those were the times of skyrocketing endowment values, and Bob's ambition came to vastly exceed my wildest dreams. But he — and the endowment — paid a heavy price when the recession of 2008 arrived. But the new labora- tory building was nearing completion; it was fortunately too late to go back. Bob Cook should be remembered as the director who success- fully brought the Arnold Arboretum back to a position where it could valuably contribute to Harvard's research and pedagogic mission, and in which it could reignite a major program in fundamental tree research — but this is his story to tell. For the first time in almost a century, the magnificent new Weld Hill Research Build- ing might serve as a magnet for a new director, who could be a leader in a field that would avail of both them and what is now again the out- standing research collection of living trees in the temperate world. And so it has befallen! In spite of severe bud- getary constraints, current Arboretum director William (Ned) Friedman has brought the new laboratory building to life with graduate stu- dents, with new faculty and classes availing of the living collections, and is attracting research- ers from other institutions. Most importantly, thanks to a new generation of faculty in OEB and changing understanding in the Harvard administration, Friedman has been able to gain the university's support for advancing the Arboretum's scholarly mission in spite of cur- rent financial constraints. And in the spirit of the original intent, the public programs have been enriched by enhancing public apprecia- tion of science. Regular research seminars have returned to the Arboretum, while the Director's Lecture Series is introducing increasing audi- ences to a variety of issues in the social as well as biological sciences. My dream has indeed come true, and with a flourish! Peter Ashton is Harvard University Bullard Professor Emeritus and was Director of the Arnold Arboretum from 1978 to 1987. He and Mary live in Somerset, England. Lighting the Night: The Use of Pitch Pine and Bayberry in Colonial New England Sheila Connor TORCHES OF PINE I n dark, small-windowed Colonial homes, the roaring fireplace brightened the room by day, and it often produced the only light available at night. Had domestic animals been abundant, the typical melted beef-suet or mutton-suet candles that the guildmakers produced in England would have been made. Tallow was scarce, however, and the inventive and resourceful settlers turned to materials ranging from extremely combustible meadow rushes soaked in lard to fish oil burned in shallow, wrought-iron holders, called Betty lamps, to illuminate their homes. These lamps An illustration of pitch pine ( Pinus rigida ) showing the cones still tightly closed, from A Description of the Genus Pinus by Aylmer Bourke Lambert, 1832. Pitch Pine and Bayberry 23 sputtered, smoked, and smelled unpleasant. A new method of lighting discovered by the colonists consisted of burning the resin-rich wood of a conifer that grew on the sandy coastal plains and ridges and in the sand barrens of river valleys. Pinus rigida earned the names candle- wood and torch pine from the Europeans after they had observed how easily the Indians pro- duced a bright flame by igniting several slivers of wood cut from its ''fat" heartwood. The colo- nists referred to these sputtering torches that dripped pitch as "splint lights." Whether growing in sterile seaside sands, where they are frequently bathed by salt spray, or rooted on exposed, windswept rocky hill tops, the torch or pitch pine thrives under adverse conditions. Easily blown over when young, a pitch pine eventually develops a root system that is substantial and deep enough to anchor it and to allow the tree to grow on an extremely dry site. Trees not more than four inches in diameter can have roots that penetrate to a depth of more than nine feet. Forest fires in these dry, windy habitats are devastating; however, not only do pitch pines survive, they often come to dominate the landscape after a fire. In New England, only Pinus rigida and the rarer P. banksiana, the jack pine — a tree of the Boreal Forest — are members of a group of coni- fers known as fire pines. These trees can with- stand fire because they have evolved several specialized characteristics. All fire pines are pioneer trees — trees able to tolerate growing in full sun. Some have a high percentage of cones that remain closed until heat generated by fire melts the resin that glues the tips of their scales together, thereby releasing their seeds. These seeds remain viable inside the cone for many years, and they have the ability to germinate on soil totally lacking a humus component. The term "serotinous," which means late-develop- ing, describes the habit of bearing closed cones that contain viable seeds for many years. Jack pines retain their tightly closed cones for so long that they often become embedded in the wood of the tree's branches and can completely disappear as the branches thicken. Pitch pine's special adaptations include a thick, protective bark, some cones that remain closed, and the ability — unusual among conifers — to sprout A mature pitch pine cone that has opened and released its seeds. Cones may persist on the tree for years. from dormant buds on the main stem or at the base of the trunk if the tree is burned or cut. In New England, wherever the soil is excep- tionally sandy, it is likely that pitch pines will he found. One of the few trees that can grow at the ocean's edge, flourish in salt marshes, and inhabit slowly moving sand dunes, Pinus rigida abounds on Cape Cod. Stunted oaks (black, red, scarlet, and white), along with the smaller post oak (Quercus stellata ) and the Cape's ubiqui- tous scrub oak (Q. ilicifolia ), are the common deciduous trees, but rising slightly above their crowns are the branches of the pitch pine, the true indicator of this sand-plain community. Usually reaching heights of less than fifty feet under the best of growing conditions, at thirty feet these pitch pines overtop the Cape's stunted forest canopy or form pure stands of low pine woods. Whether described as being New England 's most grotesque or most pic- turesque pine, a stand of P. rigida growing on a sandy hillside evokes an image of an untamed landscape. Pitch pines seldom grow straight; they twist this way and that. Their bark is remarkably rough and scaly, its color a very dark reddish gray-brown. Sparse, irregularly TIM BOLAND TIM BOLAND 24 Arnoldia 72/3 • February 2015 spaced limbs droop downward. Many of them are dead and devoid of any foliage, but they are still covered with old, open, weathered gray or blackened cones. The stiff, twisted needles grow at the ends of stout, short twigs. Each fascicle, or bundle, has three of these three- to five-inch-long yellowish-green needles. These dense clusters of needles festoon the live branches and also form tufts of foliage along the trunks. A multitude of cones with sharp, curved spines at the end of the scales also cling closely to the branches. A few of these cones mature, shed their seeds, and then fall off; most, how- ever, remain firmly attached to the branches long after their seeds have been dispersed. PITCH— THE JUICE OF THE PINE It was Pinus rigida’s imperfection as a source of illumination that proved to be a clue to its most marketable asset — its abundance of pitchy tar. In the scramble to find and develop commodities for trade, the production of naval stores — pitch, tar, rosin, and turpentine — flourished on the sand plains of the New Eng- land colonies, the home of P. rigida. As early as 1628, residents of Plymouth, Massachu- setts, requested that "men skylfull in making of pitch" be sent from England. Boiling pine tar made pitch, but extracting pine tar could be accomplished only by burning trees. To extract tar, a kiln is constructed that is much the same as that of a charcoal burner — that is, a furnace that greatly restricts the amount of air reach- ing the fire. The process requires that a pile of pitch pine be burned in the kiln as slowly as possible, often for two weeks or more, while an encircling ditch traps the liquid product as it oozes outward. The simple process of "boxing" or "milking" a tree — chopping away a section of the lower trunk, followed by chip- ping a channel in the bark — produced rosin, another salable commodity. Apparently, this process appealed to almost everyone who pos- sessed a hatchet. Although the life span of trees treated this way was shortened, a farmer could add to his yearly income by "boxing" a stand of pine for several seasons. As the production and trade of naval stores increased, whole forests of pitch pines vanished from coastal regions and from the outskirts of river valley towns. When rampant cutting of these trees occurred near the ocean, dunes became unstable, and drifting sand threatened harbors, homes, and pathways. Less than thirty years after the founding of Plymouth, rigid restrictions governing the cutting and the use of pitch pine had been established. By 1702, the town fathers forbade the taking of any pine from Plymouth's beaches. A wealth of pines grew on the sandy plains along rivers, and the rivers themselves provided an easy means for transporting forest products. Although families Northern bayberry fruits are small nutlets with a thick waxy coating. Northern bayberry ( Morelia pensylvanica [synonym Myrica pensylva- nica ]) is a shrubby plant that usually grows to a height of three to eight feet, but, in some situations, it can become a leggy shrub of fifteen feet or so. A typical plant usually assumes a dense, rounded, somewhat coni- cal shape, but in places where the plants are exposed to constant winds, such as the seashore, they form a matted ground cover about twelve to fifteen inches high. Northern bayberry is a pioneer species that can colo- nize sandy, sterile dunes, nutrient-poor abandoned fields, and disturbed waste places. It is a perfect plant for use in dune stabilization. The waxy coating on bayberry fruits is a vegetable tallow made up of stearin, palmitin, myrsitin, and glycerides. While ordinary white candles are sometimes coated with bayberry wax to give the olive green color and scent of bayberry, most of the "bayberry" candles sold today are made of a chemically scented synthetic wax or are made from the wax of one or more shrub species endemic to Central and South America that are somewhat related to the North American bayberries. Pitch Pine and Bayberry 25 Pitch pines growing on Cape Cod. NANCY ROSE TIM BOLAND 26 Arnoldia 72/3 • February 2015 Northern bayberry has leathery, dark green leaves. were allowed to continue gathering wood for lighting and fuel, the taking of pitch pine for making tar was prohibited within six miles of the Connecticut River. Massachusetts enacted conservation measures in 1715 to protect both the pine trees and the land. No one, without a license, could "cut, carry off, hark or box any pine tree...." Violation of the law carried a fine of twenty-five shillings for each tree harmed. Caught between the need to generate revenues and the desire to conserve resources, the fledg- ling government levied excise taxes, estab- lished fixed prices, and imposed controls on the quality and the quantity of naval stores. This New England industry flamed as brightly and burned out as quickly as a knot of pitch pine. By the first quarter of the eighteenth century, Multiple specimens of northern bayberry and pitch pine can be seen in the Arboretum's collections. the pine belt in the Carolmas and Georgia — a region with an abundance of yellow and loblolly pine — would claim the lead in the production of these commodities. Thus, North Carolina came to be known as the Tar Heel State and its citizens as "tarheelers." BY EARLY CANDLELIGHT For lighting the home, New England's sand- plain flora yielded an even more aromatic and cleaner-burning plant product. Sharing the abil- ity of the pitch pine to grow in pure sand, the northern bayberry ( Morelia pensylvanica [syn- onym Myrica pensylvanica ]) was abundantly distributed along the coast when the colonists arrived. The native Americans made medicinal tea from its aromatic leaves and bark and knew how to obtain wax from its "berries," but it was the new settlers who first turned the fatty coating on its berrylike nutlets into candles. Burning with a steady blue flame and emitting a pleasant, delicate odor, bayberry wax was considered by the colonists to be far superior to splint lights, pine knots, Betty lamps, and candles made from animal tallow. In autumn, after the bayberries had rip- ened, the thrifty housewife turned pounds and pounds of berries into a few precious, straight, green candles. (Between five thousand and ten thousand berries were needed to make a single two-ounce candle.) Forming low, dense mounds on seaside dunes, the many-branched, angular plants were easy to find when laden with small berries, whose color is unlike that of any other northern plant. Its hard, nutlike seeds are embedded in a waxy substance speckled with grayish or bluish gran- ules. These fruits, about a quarter of an inch in diameter, are borne by female plants, and they appear in conspicuous clusters on short spikes along the branches and at the base of the twigs of the preceding year's growth. Most of the species in the bayberry family (Myricaceae) are evergreen. Unlike the ever- green southern species, Morelia cerifera (syn- onym Myrica cerifera ), the northern bayberry is deciduous. A wise woman waited to gather the berries until several light frosts had brought the growing season to an end and the bayberry's green, shiny leaves had fallen. Stripping the Pitch Pine and Bayberry 27 berries earlier than September 10th was out- lawed in Connecticut beginning in 1724. Berry gatherers apparently ignored this legislation, however; and illegally collected berries before the authorized date. As they picked, the women and children noticed that their hands grew smooth as they acquired a thin film of wax from the berries. Inventive housewives saved some of the berries that they collected and filled cloth bags with them in order to grease the bottoms of their heavy flatirons. For candlemaking, the twigs and other debris that came home in the berry pails were removed, and the cleaned berries were placed in large cauldrons, covered with water, and heated and simmered for hours. A greenish, oily liquid floated to the top and solidified as it cooled. Repeated several times, this part of the process included straining the liquid through cloth to remove any impurities. Finally, a clear, solid cake of olive green wax resulted. The blue green water that remained was put to good use: home- makers used it to dye their homespun cloth. Patience and a steady hand came next. Dip- ping a wick twenty-five times or more into the remelted wax made a thin, tapered candle. Allowing each layer of wax to harden before the candle was dipped again meant that this process could take at least half an hour. Dipping several wicks at once saved time; only the size of the pot governed the number of candles that could be produced. Revolving candle stands that enabled the woman to dip several wicks at once decreased the time required, and tinsmiths made metal molds into which the heated wax could be poured, which eliminated the labori- ous dipping process altogether. It is no wonder that these highly prized and brittle candles, the finest light source available, were carefully stored in long, narrow boxes specifically made for holding candles. Not only were bayberry candles a useful domestic product that was saved for use on special occasions, they also became articles of trade in the colonies, and they were probably the first objects manufactured by women to be exported from New England. The English held these candles in highest regard, and they even tried to grow bayberries themselves. The French also hoped to establish bayberry plan- tations. Flowever, neither the French nor the English succeeded in bringing Morelia pensyl- vanica into cultivation on a large enough scale to support a candlemaking industry. Sheila Connor is the former Horticultural Research Archivist at the Arnold Arboretum. This article is adapted from New England Natives by Sheila Connor, Harvard University Press, 1994. 3 6673667 U.S. POSTAL SERVICE STATEMENT OF OWNERSHIP, MANAGEMENT, AND CIRCULATION (Required by 39 U.S.C. 3685) 1. Publication Title: Arnoldia. 2. Publication No: 0004-2633. 3. Filing Date: October 9, 2014. 4. 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Copies Not Distributed. Average No. Copies Each Issue During Preceding 12 Months: 115. Actual No. Copies of Single Issue Published Nearest to Filing Date: 16. i. Total. Average No. Copies Each Issue During Preceding 12 Months: 2,200. Actual No. Copies of Single Issue Published Nearest to Filing Date: 2,200. j. Percent Paid and/or Requested Circulation. Average No. Copies Each Issue During Preceding 12 Months: 76%. Actual No. Copies of Single Issue Published Nearest to Filing Date: 76%. I certify that all information furnished on this form is true and complete. Nancy Rose, Editor. Erable de Montpellier, the Montpellier Maple Katherine Urban-Mead L ast year I declared I could never love any other tree as much as a sugar maple. After accepting a several-month ecology intern- ship in Montpellier, France, I bid a teary adieu to the stunning October foliage around my Hud- son Valley home. Then 1 stepped off the airplane into a new world of dusky gray and gnarled Mediterranean greens. Ancient olive trees stand like statues in the roundabouts; streets are dot- ted with palms, cypresses, and occasional figs; tightly-pruned planetrees line esplanades and bike paths alike. There is no maple syrup here. On my first day at work, I climbed a rickety external staircase to the third floor, and with some confusion saw samaras waving from an unfamiliar tree growing alongside the stairs. Paired samaras (one-seeded fruits with papery wings) are characteristic of the maples (Acer), a group of plants I had worked with as a horti- cultural intern at the Arboretum last year. Dur- ing my internship I had puzzled over hawthorn maple (A. crataegifolium ) and communed with paperbark maple (A. griseum), but had never taken time to get to know the species that I now greeted with great glee. It was not a sugar maple, but instead the aptly-named Montpellier maple, Acer monspessulanum. After my joy at finding a local maple subsided, I had to admit that the Montpellier maple is not a particularly elegant tree. It is sometimes referred to as a shrub ( arbuste in French), with an average height of only 15 to 25 feet (4.6 to 7.6 meters). Its slow growth and small trunk, frequently branched into several stems, give it a craggy feel characteristic of many Mediterra- nean region trees. Montpellier maple's leathery three-lobed leaves are rounded and smooth- edged, are borne on long petioles, and are only 1.5 to 2.75 inches (4 to 7 centimeters) wide and 1.25 to 2 inches (3 to 5 centimeters) long. By mid-November the morning chill in Montpellier had become crisper; the endearing leaves of the tree I pass each morning turned first yellow then red. Finally brown, they fell and were scattered through the halls by passing boots. In the spring, Montpellier maple bears small, bright greenish yellow flowers that open earlier than its leaves, followed by the parallel-winged samaras frequently tinted pink or red and matur- ing to tan. This drought-tolerant species handles occasional cold and persists in USD A hardiness zones 5 to 9 (average annual minimum tempera- tures -20 to 30°F [-29 to -1°C] ; Montpellier has a Zone 9 climate). Montpellier maple is shade intolerant, so should not be sited near faster growing species. It thrives in alkaline and nutri- ent poor soils,- on a recent hike in the Cevennes I found A. monspessulanum growing on lime- stone bluffs near a holly oak (Quercus ilex) and the scrub mountain pine ( Pinus mugo ). Montpellier maple has a wide native range and corresponding variability in form. Taxonomy resource The Plant List reports five accepted subspecies — cinerascens, ibericum, persicum, turcomanicum, and microphyllum; the latter, found in Turkey, Lebanon, and Syria, has very small leaves, just 1.25 inches (3 centimeters) maximum width. Including all subspecies, Acer monspessulanum spreads across southern Europe from Portugal to Romania and across Northern Africa and east to the Hyrcanian forests in Iran and Azerbaijan. Here in southern Europe, A. monspessulanum is most often confused with the field or hedge maple, A. campestre. The field maple, however, has larger, distinctly five-lobed leaves and milky instead of clear sap. There are three specimens of Montpellier maple at the Arboretum, so you don't need to fly across the pond to find it. Accession 1491- 83-B, located just a short way down Oak Path, was wild-collected in the Lautaret botanical garden near Grenoble, France, and is currently 24 feet (7.3 meters) tall. Two other specimens are nestled in the Maple Collection along Wil- low Path. One young accession (264-2004-B; just under 10 feet [3 meters] tall) originated from a cultivated plant at the Bordeaux Botani- cal Garden. The second (12507-A), a mature tree accessioned in 1910, is an astonishing 43 feet (13 meters) tall. Bonsai enthusiasts also appreciate A. monspessulanum because its small leaves reduce even further under bonsai culture — perhaps we'll see it one day in the Arboretum's Larz Anderson collection. Although I'll always love sugar maple, there's something to be said for its sturdy Mediterra- nean cousin. I think I can make some room in my heart for two very-favorite maples. Katherine Urban-Mead was a 2014 Isabella Welles Hunnewell Intern at the Arnold Arboretum. + 1.8 + / 1 5 The Magazine of the Arnold Arboretum VOLUME 72 • NUMBER 4 ^ CRAY HERBARIUM ^ library amolaia The Magazine of the Arnold Arboretum VOLUME 72 • NUMBER 4 • 2015 CONTENTS ! ‘fUOi/ Arnoldia (ISSN 0004-2633; USPS 866-100) is published quarterly by the Arnold Arboretum of Harvard University. Periodicals postage paid at Boston, Massachusetts. Subscriptions are $20.00 per calendar year domestic, $25.00 foreign, payable in advance. Remittances may be made in U.S. dollars, by check drawn on a U.S. bank; by international money order,- or by Visa, Mastercard, or American Express. Send orders, remittances, requests to purchase back issues, change-of-address notices, and all other subscription-related communica- tions to Circulation Manager, Arnoldia, Arnold Arboretum, 125 Arborway, Boston, MA 02130- 3500. Telephone 617.524.1718; fax 617.524.1418; e-mail arnoldia@arnarb.harvard.edu Arnold Arboretum members receive a subscrip- tion to Arnoldia as a membership benefit. To become a member or receive more information, please call Wendy Krauss at 617.384.5766 or email wendy_krauss@harvard.edu Postmaster: Send address changes to Arnoldia Circulation Manager The Arnold Arboretum 125 Arborway Boston, MA 02130-3500 Nancy Rose, Editor Andy Winther, Designer Editorial Committee Phyllis Andersen Peter Del Tredici Michael S. Dosmann William (Ned) Friedman Kanchi N. Gandhi 2 The History of Minimum Temperatures at the Arnold Arboretum: Variation in Time and Space Michael S. Dosmann 12 2014 Weather Summary Sue A. Pfeiffer 20 Hamamelidaceae, Part 2: Exploring the Witch-hazel Relatives of the Arnold Arboretum Andrew Gapinski 36 Pterostyrax hispidus, the Fragrant Epaulette Tree Pamela J. Thompson Front and back covers: After a stunningly cold and snowy winter in Boston, spring's colorful flowers and fresh foliage will be especially welcome. The Malus collection on Peters Hill (with Hemlock Hill, the summit of Bussey Hill, and the Boston skyline in the background) is seen in this image from early May, 2008. Photo by Nancy Rose. Inside front cover : The fragrant flowers of Magnolia 'Judy Zuk' (accession 183-2011) were in bloom last year on May 19. This hybrid cultivar has M. acuminata, M. liliiflora, and M. stellata in its parentage. Photo by Kyle Port. Inside back cover: The pendent panicles of fringed flowers on Pterostyrax hispidus lead to its common name, fragrant epaulette tree. Photo by Pamela J. Thompson. Copyright © 2015. The President and Fellows of Harvard College TFc ARNOLD ARBORETUM of HARVARD UNIVERSITY The History of Minimum Temperatures at the Arnold Arboretum: Variation in Time and Space Michael S. Dosmann G iven the original charge to cultivate "all the trees, shrubs, and herbaceous plants, either indigenous or exotic, which can be raised in the open air," it's not surprising that the Arnold Arboretum has long been interested in documenting local climate and weather, par- ticularly as they relate to plant hardiness. Early publications such as Garden and Forest and Arnoldia’s predecessor, the Bulletin of Popu- lar Information, are replete with notes of what did and did not survive New England's climate. Arnoldia continues that theme with annual summaries of the previous year's weather (see page 12 in this issue), often with notes on plant performance. One of the most innovative projects link- ing plants and climate was Alfred Rehder's creation of the first Arnold Arboretum Hardi- ness Zone Map, which was published in the first edition of his Manual of Cultivated Trees and Shrubs Hardy in North America (Rehder 1927). On this map, Rehder divided the United States into eight different zones based on the average minimum temperature of the cold- est month. Then, using information about what survived the winters in Boston and other regions, he assigned plants in his Manual to particular Arnold Arboretum zones of maxi- mum hardiness. This novel application was further updated and improved by the Arnold Arboretum, and later inspired and gave rise to the hardiness zone map (see page 9) created and now perpetuated by the United States Depart- ment of Agriculture (USDA). (See Del Tredici 1 990 for a broader review, as well as Dosmann and Aiello 2013 for a brief discussion on the 2012 version of the map and its application to plant acquisition and collections planning.) It is important to bear in mind that the zone parameters in the Arnold Arboretum scheme were different from those in the USDA's, thus giving rise to confusion about a species' cold tolerance, particularly when a species was sim- ply said to be "hardy to Zone 6" without fur- ther clarification— was it the Arnold's Zone 6 (average annual minimum temperature -5 to 5°F [-20.6 to - 1 5°C] ) or the USDA's Zone 6 (-10 to 0°F [-23.3 to -17.8°C])? The Arnold Arboretum map was last updated in 1971, and the now accepted industry stan- dard, the USDA Plant Hardiness Zone Map, is based on the principle of average annual mini- mum temperature. Although other climatic fac- tors (e.g., heat, rainfall, wind) certainly affect a plant's ability to survive in a given location, it is the minimum temperature in winter that is a primary driver of plant survival. The Arbore- tum lies within USDA Hardiness Zone 6. This means that in most winters we can expect a minimum temperature between -10 and 0°F, but it does not mean that temperatures lower than -10°F do not occur. Just as the Arboretum has been curating plant data for almost 150 years, it has also been gath- ering and archiving weather data for nearly a century. Starting in 1918, William Judd, Arbo- retum propagator at the time, began to collect and record weather statistics on a daily basis. He collected these data near the greenhouse, which at the time was located near the former Bussey Institution and what is now the Mas- sachusetts State Laboratory near the Forest Hills train station. Judd diligently recorded the data until his death in 1946, leaving us with a wonderful resource. In 1963, a new weather station was installed at the Dana Greenhouses (which had been constructed the previous year) and the Arboretum began to collect data again in earnest (Fordham 1970). In 2011, a new state-of-the-art weather station was erected at Arboretum Microclimates 3 Location of Weather Stations at the Arnold Arboretum of Harvard University 0.25 Mi Hunnewell Visitor Center N A Weld Hill Research Building I Weld Hill 1 75 ft. Weather Stations Years Active O Current • 2009-2014 1934-1935 O 1918-1946 Over almost a century the Arboretum has acquired temperature data from three permanent stations (William Judd's measurements at the former Arboretum greenhouse [1918-1946]; the Dana Greenhouses; and the Weld Hill Research Building) as well as tempo- rary stations set up by Hugh Raup (1934-1935) and, most recently, data loggers located throughout the grounds (2009-2014). IORDAN WOOD 4 Arnoldia 72/4 • April 2015 the Weld Hill Research Building, which, among other attributes, allows digital archiving of data and access via the web. Although there is a 17-year gap between the end of the Judd period and the beginning of data collection at the Dana Greenhouses, the long-term collection has yielded volumes of information. One notable finding is the dra- matic variability over time in the extreme minimum temperature events. The figure below depicts the temperatures from three Arboretum weather stations; I also included the annual minimum temperatures recorded at the Blue Hill Observatory (elevation 635 feet [194 meters]) in Milton, Massachusetts, some 8 miles south of the Arboretum. (Blue Hill Observatory has been collecting weather data since 1885 and is the oldest continuously operating weather observatory in the United States.) At the Arboretum, annual minimum temperatures have, by and large, stayed within the USDA Zone 6 range. However, there have been notable exceptions, including the bitter winters of 1933 and 1934 when Judd noted the thermometer hitting -17 and -18°F (-27.2 and -27.8°C), respectively. These were clearly Zone 5 (-20 to -10°F [-28.9 to -23.3°C]) winters, and the Arboretum documented the death of plants that could not tolerate that extreme. It has been thirty years since the Arboretum experi- enced a Zone 5 winter, and it was borderline (the Dana Greenhouse thermometer measured -10°F). Since then, annual minimum tempera- tures have remained in the Zone 6 range, with a number of years experiencing even warmer minimums. Are these due to climate change, or urban heat island effect? Perhaps a combination of both. Do these trends place the Arboretum in a new hardiness zone? I do not believe so. Even if 9 out of 10, or even 19 out of 20 winters never creep below 0°F (i.e., are in the Zone 7 range), all it takes is one Zone 6 winter to elimi- Blue Hill Observatory a William Judd ♦ Dana Greenhouse • Weld Hill Year Annual minimum temperatures from the three permanent stations at the Arboretum, plus the annual minimum temperatures recorded since 1885 at the Blue Hill Observatory for comparison. Arboretum Microclimates 5 nate those plants unable to survive at those temperatures. It pays to he conservative when playing the hardiness game. Location, Location, Location In examining nearly a century of annual varia- tion in minimum temperature at the Arbore- tum, one must bear in mind that those data were obtained from three separate and distinct locations, each with its own elevation and prox- imity to buffering buildings or canopies, as well as differences in aspect. And although we know that the present Weld Hill and Dana Green- house stations are sufficiently far away from buildings not to be influenced by them, we are not exactly sure where Judd's station was — it may have been somewhat protected. The Arbo- retum landscape comprises some 281 acres, with elevations that range from 44 feet (13.4 meters) above sea level in the Meadow by the Hunnewell Building to 240 feet (73.2 meters) on the summit of Peters Hill. Peters, Hemlock, and Bussey Hills each have their own character and microclimates distinct from surrounding areas. / 1*? /lea J-C-A *1 J. ^ v -/ ‘ JV. // ' S'. o->si , Cjr. ** '• /O /' 7/ tit*. / ^ /3 mjcL / -'V ^ j; ° VT , JO *• * , - 2 s«*' 31 y . t ^ 3 2 . l.t-h / cAjck L ii ^ah c- • •-«. ^ ’oU, - i 4 4 T i