Brassicaceae (Mustard Introductory article

Family) . Introduction
Article Contents

Ihsan A Al-Shehbaz, Missouri Botanical Garden, St. Louis, Missouri, USA . Related Families

. Economic Importance

. Horticultural Importance

. Morphology

. Ecology

. Dispersal

. Biogeography

. Fossil History
. Phylogeny

Online posting date: 15th July 2011

The Brassicaceae (Cruciferae) or mustard family is a well- characters, and convergence (homoplasy) is known in
defined group of about 310 genera and some 3500 species almost every conceivable morphological character.
distributed primarily in the temperate and alpine areas of The family is primarily herbaceous, and nearly two-
all continents except Antarctia. It is most highly diversi- thirds of species are perennial. About 5% of species are
fied in central and western Asia, Mediterranean Europe
woody, and typical shrubs evolved independently in 16
genera and about 2% of the family species total. They
and western North America. This article discusses the eco-
include Macaronesian species of Crambe, Descurainia,
nomic importance of the family (food, oils, condiments, Erysimum and Parolinia, north African Foleyola, Afro-
ornamentals and weeds) and role played by one of its Asian Zilla and Farsetia, South African Heliophila and
weedy member, the model organism Arabidopsis thaliana, some Australian Lepidium. The last three genera include
in the advancement of modern experimental biology. shrubs more than 2 m tall and small annuals rarely reaching
Here we also review the morphology, biogeography, 10 cm in height. Typical climbers are found in one species
ecology and phylogenetic relationship within Brassica- each of Australian Lepidium and South African Heliophila
ceae and to other families. We also cover the significance and three species each of South American Cremolobus and
of molecular data in dividing the family into 48 mono- Polypsecadium (Khanna and Rollins, 1965; Appel and
phyletic tribes and in determining its major lineages. Al-Shehbaz, 2003; Al-Shehbaz, 2006).
Finally, a brief discussion is presented on the whole-gen-
The family has been surveyed extensively for chromo-
some numbers in about 45% of the species. As shown below,
ome duplication events and their possible role in the
earlier estimates of nearly 60% of the family as diploids
radiation and diversification of the family. could easily respresent ancient ploidy events. The lowest
haploid chromosome number (n=4) is known in some
species of the Australian Stenopetalon and several of the
western North American Physaria, whereas the highest
number recorded thus far (n=128) is from the eastern North
Introduction American Cardamine (Warwick and Al-Shehbaz, 2006).
The Brassicaceae (mustard family) include about 310
genera and some 3500 species distributed worldwide
(author’s compilation). These revised estimates are slightly Related Families
lower than the 338 genera and 3709 species in Warwick
et al. (2006). Although, the family is easily distinguished by
The Brassicaceae have traditionally been considered a
its fruits and relatively uniform flowers (see ‘Morphology’),
natural group, and recent molecular studies support its
it is well known to be taxonomically difficult at the generic
monophyly. It is the largest member of the Brassicales (398
rank. Relatively few genera are distinguished by unique
genera and 4450 species), an order that includes 17 families
all of which contain mustard-oil glucosides (glucosino-
eLS subject area: Plant Science lates) and myrosin cells (Stevens, 2001). Upon crushing the
fresh parts of plants of these families, the enzyme myr-
How to cite: osinase is released from the myrosin cells and hydrolyses
Al-Shehbaz, Ihsan A (July 2011) Brassicaceae (Mustard Family). In: eLS.
the glucosinolates to release the pungent mustard oils
John Wiley & Sons, Ltd: Chichester.
DOI: 10.1002/9780470015902.a0003690.pub2
(isothiocyanates and their by products). The Brassicaceae
are most closely related to the sister family Cleomaceae and

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 Brassicaceae (Mustard Family)

together they form a lineage sister to the family Cappar- and preparations are used to treat dysentery, cold, coughs,
aceae. An earlier cladistic study (Judd et al., 1994), which asthma and diabetes. However, these attributes have not yet
was based on minimal sampling of the three families, sug- been subjected to critical modern studies.
gested their merger into a more inclusive Brassicaceae. The family also includes about 130 species of weeds,
However, subsequent molecular studies (Hall et al., 2002) especially in the genera Lepidium, Sisymbrium, Brassica,
did not support that view, and taxonomists almost uni- Cardamine and Camelina. Shepherd’s purse, Capsella
versally now favour the recognition of three families bursa-pastoris, is considered the second most common
instead of one. weed on Earth. Some weeds are hosts to fungal and viral
parasites of crop mustards. Cattle feeding on large quan-
tities of Brassicaceae weeds often produce tainted milk due
Economic Importance to the presence of sulfur compounds such as glucosinolates.
Arabidopsis thaliana (thale cress, mouse-ear cress),
The family includes several species of considerable eco- sometimes called ‘the drosophila of the plant kingdom’, is
nomic importance, especially as vegetable crops and the most widely utilised model plant in experimental biol-
sources of spices and edible and industrial oils (see Al- ogy. Its superior qualities as a laboratory organism include
Shehbaz, 1984, 1985; Appel and Al-Shehbaz, 2003). Crops having the smallest genome and least repetitive deoxy-
of the genus Brassica were utilised in India as far back as ribonucleic acid (DNA) among flowering plant, as well as
3000 BC, as evidenced from Sanskrit records, and some low chromosome number (10 chromosomes), short gen-
believe that the ancestors of cabbage were grown along eration time (about 5 weeks from seed germination to
coastal Europe nearly 8000 years ago. The fresh parts are production of fruits and seeds), small plant size (dozens can
eaten raw, fermented in brine, cooked, stewed or pickled in be grown in a small pot and several thousands in a small
vinegar. The important vegetable crops belong to Brassica growth chamber or room) and ease to grow on synthetic
oleracea and include cabbage (var. capitata), cauliflower media. It is used in fields such as genetics, development,
(var. botrytis), broccoli (var. italica), Brussels sprouts (var. physiology, crop improvement, disease resistance, ecology,
gemmifera), kohlrabi (var. gongylodes) and kales and col- evolution and population biology. Its entire genome was
lards (var. acephala). Other vegetable crops include turnip fully sequenced by the end of 2000. See also: Arabidopsis
(Brassica rapa), rape and rutabaga (Brassica napus), radish thaliana as an Experimental Organism
(Raphanus sativus), water cress (Nasturtium officinale),
cress (Lepidium sativum) and arugula or salad rocket
(Eruca vesicaria subsp. sativa). Human selection of radish Horticultural Importance
roots gave an enormous array of forms ranging from the
size of a cherry to giant Japanese radishes up to 1 m long The Brassicaceae includes a limited number of species that
and weighing up to 50 kg. A wide range of leafy forms, are cultivated as ornamentals. These include aubrietia
originally selected in China and now cultivated worldwide, (Aubrieta deltoidea), wallflower (Erysimum cheiri), candy-
belong to B. rapa (Chinese cabbage, bok choy) and Indian tuft (several species of Iberis), dame’s rocket or violet
mustard Brassica juncea. See also: Crop Plants: Evolution (Hesperis matronalis), honesty or money plant (Lunaria
Seeds of the Brassicaceae are rich in oils, and some yield annua), rock cress (Arabis), basket of gold or golden-tuft
oil contents as high as 40%. Canola is extracted from alyssum (Aurinia saxatilis), stock (Matthiola incana), sweet
rapeseed (B. napus subsp. napus) but other oils in Asia are alyssum (Lobularia maritima) and several species of
obtained from B. rapa (=Brassica campestris), B. juncea Aethionema, Draba, Malcolmia and Moricandia. Orna-
and black mustard Brassica nigra. Indeed, oils of Brassi- mental cabbage is a colour form selected from B. oleracea
caceae rank first in terms of the world’s overall tonnage var. acephala.
production. Industrial oils extracted from E. vesicaria and
other mustards are utilised in the manufacture of lubri-
cants, grease, lacquers, varnishes, plastics, soft soap, vinyl Morphology
stabilisers, resins, insect repellents, pharmaceuticals,
nylons and synthetic odours. The seedcake remaining after Plants of the Brassicaceae are annual, biennial or perennial
oil extraction has high protein contents (20–35%) and is herbs and rarely grow into woody shrubs. They have a
used as a fertiliser. watery sap that contains the nonpoisonous mustard-oil
The table mustard is manufactured from seeds of Sinapis glucosides (glucosinolates), a group of over 100 com-
alba and B. juncea or B. nigra. Mustard seeds are also used pounds that yield the pungent mustard oils (isothiocyantes)
as a spice and in pickling. The grated fleshy roots of the upon chewing the green parts. The leaves are often in a
European horseradish (Armoracia rusticana) and Japanese basal rosette, and stem leaves (when present) are alternate
wasabi (Eutrema japonica) yield the hot condiments used or rarely opposite. They are simple or rarely compound and
worldwide. without stipules. The flowers are radially symmetrical and
Many medicinal attributes linked to species of Brassica grouped in racemes or sometimes solitary on pedicels that
and Raphanus exist in the earlier records from Asia. These originate from basal rosettes. The flowers are bisexual, and
include laxatives, stimulants, emetics, tonics and antiseptics unisexual flowers are very rare. The four sepals are free or

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 Brassicaceae (Mustard Family)

rarely united, and they alternate with four petals in the which exhibit enormous diversity and used extensively in
form of a cross forming known a cruciform corolla, hence the determination of species and genera (Figure 2), are
the family name Cruciferae (Figure 1). The petals are typically a two-valved capsules usually dehiscing longi-
sometimes reduced or absent. The stamens are six, tetra- tudinally and leaving behind the placental frame (replum)
dynamous (outer pair shorter than inner two pairs), and and the septum. They are often called siliques (fruit three or
rarely are subequal in length, in three pairs of unequal more times longer than wide) or silicles (fruit less than three
length. Many Lepidium species have two or four stamens, times longer than wide), but indehiscent, nutlike, schizo-
and the Himalayan Megacarpaea polyandra has 18–24 carpic, winged or segmented fruits are also found. The
stamens. The nectar glands are always present on the embryo is oily, occupies the entire seeds, and is strongly
receptacle at the base stamens. The pistil is two-carpelled, curved or variously folded. The curvature of the radicle
two-loculed (one-loculed and the septum absent), and the (embryonic root) in relation to the cotyledons is important
placentation is parietal or rarely subapical. The fruits, taxonomically.
The Brassicaceae family is easily distinguished by having
the cruciform corolla, tetradynamous stamens, capsular
fruits described above, strongly curved embryos and pun-
gent watery sap.

Ecology
Species of the Brassicaceae occupy a wide range of habitats.
Members of the genera Nasturtium (water cress) and
Subularia, as well as a few of Cardamine and Rorippa, are
typically freshwater aquatics. By contrast, all except one
species of the sea rocket genus Cakile, some forms of the
wild radish Raphanus raphanistrum and Crambe maritima
are strand plants that are common along sandy beaches a
little beyond the reach of high tides. These strand plants are
Figure 1 Flower of Brassicaceae: left: lateral view showing one of the two often succulent, and they depend on sea water for the dis-
short stamens and two of the four long stamens; right: top view. persal of their corky fruits. Members of the genus Draba are

Figure 2 Fruit diversity of Brassicaceae.

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 Brassicaceae (Mustard Family)

most commonly found in cold climates, especially in the Raphanus) are strand plants that depend primarily on see
high alpine areas and in northern latitudes (70–808N) well currents of dispersal.
into the Arctic Circle. In fact some species of Draba flower
most of the plant is covered with snow. One species of Reproductive biology
the Himalayan Lepidostemon, Lepidostemon everstianus,
grows on scree at altitudes about 6400 m on the northern Except for weeds or members with weedy tendencies, in
slopes of Mt. Everest (Al-Shehbaz, 2000), and very few which self-pollination or autogamy is predominant, the rest
vascular plants can survive at such high elevations. The of the family includes species with showy flowers that are
majority of species in the family occupy arid habitats that pollinated primarily by insects. Bees, flies, butterflies and
receive only a minimal annual rainfall. Many species grow moths are the principal pollinators. Bird pollination is
in somewhat mesic habitats, and representatives of only a unknown in the family, and wind pollination is known thus
few genera (e.g. Cardamine) are restricted to forests. Weedy far only in the Kerguelen cabbage (Pringlea antiscorbutica),
species are abundant in disturbed habitats, including a species restricted to Kerguelen, Crozet, Prince Edward,
roadsides, ditches, waste places, farms, abandoned fields Marion, McDonald and Herd islands of the south Indian
and the like. See also: Arctic Ecosystems; Lake Ecosystems; Ocean at latitudes 45–558S. In this species the flowers are
Mediterranean Ecosystems green and densely grouped in spikes, have long staminal
filaments and large stigmas, and lack the petals or flower
odour (Al-Shehbaz, 1984). See also: Pollination by Animals
Dispersal In numerous species the flowers show adaptations that
promote outcrossing and cross-pollination. The most
Fruits and/or seeds of members of the family are adapted to common one is protogyny and less commonly protandry
different kinds of dispersal mechanisms. For example, (see ‘Glossary’ and Al-Shehbaz, 1977). Dioecism in known
winged seeds or fruits, inflated bladder-like fruits, and the in two species of Lepidium endemic to New Zealand
dust-like seeds of some of the desert species (e.g. Diplotaxis, (Heenan et al., 2007), and gynodioecism is extremely rare in
which weigh as little as 0.05 mg), are readily dispersed by the family (Garnock-Jones, 1991).
wind (Al-Shehbaz, 1985). In the majority of the family, the Asexual reproduction is manifested in the production of
seeds are generally small and rarely do they reach 4 mm in propagules (bulbils, rhizomes, tubers, aerial rosettes) in
length. They are often dispersed by rain washes and/or various genera, but perhaps the most notable one is apo-
wind. In numerous species the seed coat becomes muci- mixis. The latter has been reported in a few species of Draba
laginous when wetted, and this helps in anchoring the seeds and Erysimum, but it appears to be far more common in the
to the soil or in sticking to the fur of mammals or feathers of North American Boechera, where well over 60 species are
birds. In fact, long-distance dispersal by birds is attributed apomictic (see Windham and Al-Shehbaz, 2007; Taskin
to the presence of mucilage in the epidermal layer of the et al., 2009; Aliyu et al., 2010; Sharbel et al., 2010, and
seed coat. Many of the alien weeds became established references therein).
through the transport of animal fleeces. The Central Asian The most effective system that enforces outbreeding in
Megacarpaea gigantea has the largest seeds in the family the family is the sporophytic self-incompatibility. Here the
(up to 1.8  1.5 cm), but the seeds are strongly flattened and pollen germination on a given stigma is determined by the
they are enclosed in broadly winged fruit valves to aid their genotype of the pollen-producing plant. Two genes, each
dispersal by wind. The ‘rose of Jericho’, Anastatica hier- sometime with numerous (to 50) alleles in a given species
ochuntica, which is distributed along a stretch of 8000 km (Nasrallah, 1997), control this sterility (S) system and their
from the hot deserts of Mauritania in northwestern Africa inheritance follow a single Mendelian locus. The S-locus
through the Middle East into Pakistan, grows primarily on receptor protein kinase (SRK) gene encodes a gene
sand, and when the plant is dry, it curls like a ball and expressed on the stigma surface. The S-locus cysteine-rich
tumbles for long distances. Once the plant receives some protein (SCR) gene is expressed on the pollen surface. If a
moisture, it opens up and releases the seeds, hence the name pollen grain from a plant falls on a stigma on the same
tumbling or resurrection mustard. Species that have fruits plant, or a stigma of a plant that shares an S allele with
with hooks, spines or sticky glands are dispersed by ani- plant donating the pollen, then SCR pollen coat protein
mals, but this type of dispersal is rather uncommon in the binds with SRK protein on that stigma leading to receptor
family. The fruits of species of Cardamine dehisce explo- activation and inhibition of pollen-tube development. By
sively, but they release the seeds only a few feet from contrast, in ‘nonself’ pollen, which does not carry a shared
the mother plant. Another rare dispersal in the family is allele between its donor and that of the stigma surface, the
geocarpy, which is known in the South European SCR protein would not bind with SRK and thus no acti-
(Corsica, Sardinia) Morisia monanthos, the South American vation takes place and as a result pollen-tube development
Cardamine chenopodiifolia, the Australian Geococcus would proceed normally (Nasrallah, 2002).
pusillus, north African Raffenaldia and the Himalayan Breaking down of the self-incompatibility system took
Aphragmus. In these species, the fruiting pedicel bends place many times in the Brassicaceae, and classic examples
downward and buries the fruit next to the parental plant. are demonstrated within and among species of the genera
Only about eight species in the family (Cakile, Crambe and Leavenworthia (Busch et al., 2010, and references therein)

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 Brassicaceae (Mustard Family)

and Arabidopsis (Mable et al., 2005). Although A. thaliana

is self-compatible, most of its wild relatives are self-
incompatible. Through a clever genetic manipulation,
Nasrallah et al. (2002) successfully generated a self-
incompatible A. thaliana by the transfer of two S-locus
genes from Arabidopsis lyrata. The molecular basis of such
a breakdown in the incompatibility system is presented in
Shimizu et al. (2004).

Biogeography
The family is distributed on all continents except Ant-
arctica. It is quite abundant in the temperate and alpine
regions of the northern hemisphere, less widely distributed
in the southern hemisphere, and restricted in the tropics to
the alpine areas. The centres of highest diversity of native
species in the family include the Irano-Turanian region
(with approximately 900 species, of which some 530
are endemic), North and Central America (973 species, 541
endemic), and the Mediterranean region (630 species, 290
endemic). Other smaller centres include the Saharo-
Sindian region (180 species), South America along the
Andes from Colombia into Patagonia (367 species), South
Africa (nearly 110 species) and Australia and New Zealand Figure 3 Pollen of Brassicaceae. Top: Streptanthus carinatus (representing
(about 120 species). All genera and species now indigenous ca. 96% of the family). Bottom: Physaria gordonii, tribe Physarieae
to the southern hemisphere have their ancestors in the (representing ca. 4% of the family).
northern hemisphere, where the family first evolved.
However, there is disagreement about the centre of origin the Oligocene of Montana shows remarkable similarities to
of the family, and there is increasing evidence that the the modern and extant Thlaspi arvense (Manchester and
family most likely originated in the Irano-Turanian region O’Leary, 2010). However, the fossil record is so frag-
or Southwest Asia. See also: Biogeographical Regions mentary that it hardly has any value in the study of
The largest genus in the family is Draba (about 380 phylogenetic relationships within the family. By far the
species: north temperate and the Andes of South America), most common type of fossils is that of pollen grains, which
and the other large genera include Alyssum (180 species: has been recorded from the Cretaceous of New Zealand
Eurasia), Boechera (110 species, North America), Carda- and the Upper Miocene of France (for references, see
mine (about 200: worldwide), Erysimum (about 165: Al-Shehbaz, 1984). Unfortunately, the pollen of mustards
primarily Eurasia), Heliophila (90: South Africa), Isatis is almost universally uniform and of no value in the
(70: Eurasia), Lepidium (about 250: worldwide), Noccaea determination of genera. The single exception is the pri-
(110: mostly Eurasia), Physaria (106: mostly North marily North American tribe Physarieae in which the
America) and Rorippa (85: worldwide). These 11 genera pollen has 4–10 colpi, compared to the three-colpate pollen
collectively have 1746 species, or about 50% of the family in the rest of the family (Al-Shehbaz et al., 2006; see
total. The majority of genera (213) include one to five Figure 3). Furthermore, it is sometimes difficult to assign
species totalling 405 species, or 11.6% of the family total pollen to a given family, and the Brassicaceae are no
(author’s compilation). About 110 genera are unispecific exception. See also: Fossil Record
(with one species), and many may eventually be synony-
mised with larger genera. Only Cardamine, Lepidium
and Rorippa are represented by indigenous species on all
continents except Antarctica.
Phylogeny
Fossil History Attempts from the early nineteenth century to the early
1990s to study the phylogenetic relationships within the
The Brassicaceae is rather poorly represented in the fossil Brassicaceae based solely on morphology have led to the
records. Macrofossils, such as fruits and seeds, of some creation of several controversial and highly artificial sys-
genera (e.g. Clypeola, Draba, Lepidium and Sinapis) were tems of classifications (e.g. Hayek, 1911; Janchen, 1942;
reported from the Upper Pliocene of Germany (see also Schulz, 1936). The lack of agreement among previous
Al-Shehbaz, 1984). A fruit fossil of the genus Thlaspi from family classifications is attributed to emphases on few fruit

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 Brassicaceae (Mustard Family)

characters that have recently been shown to be subject to markers studied thus far did not diverge much during that
substantial convergence. period and subsequently.
Based on extensive molecular studies from 2006 onward
and using nearly a dozen nuclear, chloroplast and mito-
chondrial DNA markers (Bailey et al., 2006; Beilstein et al., Genome duplication
2006, 2008; German et al., 2009; Franzke et al., 2009;
Khosravi et al., 2009; Couvreur et al., 2010; Warwick et al., The Brassicaceae exhibit tremendous diversity in genome
2010, 2009), the mustard family is currently divided into 48 size (Lysák et al., 2009). Based on detailed genomic studies
monophyletic and morphologically well-defined tribes that on A. thaliana, it was shown that its 10 chromosomes
encompass nearly 93% of the genera. As currently under- reflects the product of three ancient whole-genome dupli-
stood, the family is divided into two groups, of which the cations, and its current chromosome number is derived
small tribe Aethionemeae (Aethionema and its ca. 35 spe- from ancestors with 16 chromosomes (Lysák et al., 2006,
cies) is sister to an unresolved polytomy including the 2009; Mandáková et al., 2010). Similar studies on other
remaining 47 tribes or core Brassicaceae. This core is div- mustards, especially the economically important tribe
ided into three major lineages encompasing 26 tribes that Brassiceae (Lysák et al., 2005), supported the genome tri-
include the vast majority of species (Koch and Al-Shehbaz, plication for the tribe. With the likely exception of
2009; Warwick et al., 2010; Franzke et al., 2011). All of Aethionema, the vast majority of mustards previously
the remaining 21 tribes, including the larger Arabideae believed to be diploids are most likely the product of
and Alysseae, are individually well supported, but they too three ancient whole genome duplications. Of these, the
are part of the unresolved basal polytomy of the family oldest probably took place during the diversification of
(Figure 4). Lineage I includes 15 tribes with branched tri- flowering plants, the second within the order Brassicales,
chomes and no multicellular glands, lineage II has pri- and the most recent one was specific to core Brassicaceae.
marily simple trichomes, and lineage III has branched Genome-size variation does not necessarily reflect whole-
trichomes and multicellular glands. The model organism A. genome triplication because they are followed by genome
thaliana belongs to the tribe Camelineae of lineage I, and downsizing and extensive diploidisation (Lysák, 2009;
the cultivated crops of Brassica belong to the tribe Brassi- Mandáková et al., 2010).
ceae of lineage II. It is believed that the lack of basal The age of Brassicaceae was estimated between 19
resolution in the family was probably the product of an (Franzke et al., 2009) and 55 Ma (Beilstein et al., 2010).
early rapid radiation the family into drier habitats, espe- It has been speculated that genome duplications provided
cially in the Irano-Turanian region, and that the molecular the raw genetic material for the rapid radiation and

Capparaceae
Cleomaceae
Aethionemeae
Alyssopsideae, Boechereae, Camelineae,
Cardamineae, Crucihimalayeae, Descurainieae,
Lineage I
Erysimieae, Halimolobeae, Lepidieae,
Microlepidieae, Oreophytoneae, Physarieae,
Smelowskieae, Turritideae, Yinshanieae

Lineage III Anastaticeae, Anchonieae, Buniadeae,

Chorisporeae, Dontostemoneae, Euclidieae,
Hesperideae

Alysseae, Aphragmeae, Arabideeae,

Asteae, Biscutelleae, Calepineae,
Cochlearieae, Coluteocarpeae, Conringieae,
Cremolobeae, Eudemeae, Eutremeae,
Heliophileae, Iberideae, Kernereae,
Megacarpaeeae, Notothlaspideae, Schizopetaleae,
Scoliaxoneae, Steveneae, Thlaspideae

Lineage II Brassiceae, Isatideae, Sisymbrieae

Thelypodieae

Figure 4 A highly simplified cladogram showing the three major lineages and tribes of the Brassicaceae. It is modified from Franzke et al. (2011); German
et al. (2009); German and Al-Shehbaz (2010); and Warwick et al. (2010 and in press). Each of the 21 tribes not in the boxed three lineages is connected
directly to the basal polytomy. Their grouping in threes do not reflect relationships and is intended only to simplify the phylogenetic tree.

6 eLS & 2011, John Wiley & Sons, Ltd. www.els.net

 Brassicaceae (Mustard Family)

diversification of the family coupled with the availability of German DA and Al-Shehbaz IA (2010) Nomenclatural novelties
drier habitat during its early evolution (Franzke et al., 2011). in miscellaneous Asian Brassicaceae (Cruciferae). Nordic
Journal of Botany 28: 646–651.
German DA, Friesen N, Neuffer B et al. (2009) Contribution
to ITS phylogeny of the Brassicaceae, with a special reference
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33–56.
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Botany 2: 327–333. etischer Grundlage. Beihefte zum Botanischen Centralblatt 27:
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