EDIBLE PLANTS

Eduardo H. Rapoport and Barbara S. Drausal

Universidad Nacional del Comahue and CONICET, Argentina

I. Food Habits each animal lives. Since the geographic ranges of species
II. The Diversity of Food Plants are relatively widespread, the individuals of a given
III. Geographic Patterns of Food Plants animal species may vary their food resources in different
IV. Are Edible Weeds, Weeds? sites of the range, according to their opportunities. For
this reason, the variety of plants ingested by a given
species is always greater than the variety of plants in-
gested by an individual or by an entire population.
GLOSSARY Domestic as well as wild herbivores may eat a wide
variety of food items, but they have clear preferences
cultivar Cultivated variety or genetic strain of a domes- for particular plant species. Some ungulates are capable
ticated food plant. of selecting the most nutritious individual plants among
domesticate Plant that has been selected by humans those of the same species. They select forage mainly by
and adapted for use as a food crop, nutrient, fiber, smell, and secondarily by taste. Volatile substances in
or other purpose. the plants may either inhibit or attract foragers, and
ethnobotany Study of the variety, natural history, and are largely responsible for their palatability. According
characteristics of the plants used by human cultures. to Klein (1970), the nutritive value of plants available
to wild ruminants depends on the stage of maturity of
the vegetation, with highest nutritive quality coinciding
with the initiation of growth, as well as with soil type
THE VARIETY OF PLANTS NORMALLY CONSUMED and climate. Rapid growth in plants is correlated with
BY HUMANS represents a tiny proportion of what na- high nutritive quality. Similar conclusions were re-
ture supplies. Of the estimated 270,000 plant species ported by Gardarsson and Moss (1970) in a study of
recognized in the world, about 12,500 species from food selection by the Icelandic ptarmigan (Lagopus mu-
over 3000 genera are considered edible to humans. tus). This bird consumed leaves and flowers of 8, 11,
10, and 11 species, respectively, in summer, autumn,
winter, and spring.
I. FOOD HABITS Similarly, the European hare (Lepus europaeus) in
northwestern Patagonia makes use of 17 to 21 species
Animals, being terrestrial or marine, have limitations of plants in a given season out of a total of 28 species
with respect to the variety of species they consume. that it consumes over the year. Table I provides a short
They depend on what nature offers in the place where sample of the variety of food consumed by different

Encyclopedia of Biodiversity, Volume 2

Copyright  2001 by Academic Press. All rights of reproduction in any form reserved. 375
376 EDIBLE PLANTS

TABLE I
The Number of Food Plants Consumed Annually by Different Mammal Species

Mammal species Common name No. of plant species Source

Alouatta fusca Brown howler monkey, SE Brazil 52 Galetti et al. (1994)

Ateles spp. Spider monkey, Panama 14 Milton (1981)
Bos taurus Cattle, NW Patagonia 23 Relva (1998)
Capra hircus Goat, Mendoza, Argentina 76 Dalmasso et al. (1995)
Cebus apella Capuchin monkey, SE Brazil 73 Galetti and Pedroni (1994)
Cervus elaphus European red deer, NW Patagonia 34 Relva (1998)
Chiropotes satanas Monkey, Venezuela 29 Kinsey and Norconk (1993)
Ctenomys mendocinus Tuco-tuco, Argentina 28 Madoeri (1993)
Lagidium viscacia Vizcacha de la sierra, Argentina 21 Galende and Grigera (1998)
Lama guanicoe Guanaco, Mendoza, Argentina 47 Candia and Dalmasso (1995)
Lepus europaeus European hare, NW Patagonia 28 Galende and Grigera (1998)
Ovis aries Soay sheep, St. Kilka Island, U.K. 앑12 Gwynne and Boyd (1970)
Pithecia pithecia Monkey, Venezuela 25 Kinsey and Norconk (1993)

herbivorous and omnivorous mammals. The case of vegetables, fruits, grains, nuts, and condiments in an
the Soay sheep was included to show how a domestic exceptionally well-provisioned supermarket, the figure
herbivore may restrict its diet in a species-poor environ- (including different varieties and brands) may rise to
ment. Of course, the range of foods ingested by other 600 according to Duke (1992).
animals may vary widely. Monophagous insects restrict The stomach contents of two mummies that were
themselves to only one plant species, soil amoebae found well-preserved in Danish bogs provided interest-
(Acanthamoeba) normally ingest five species of micro- ing information about the gastronomic habits of people
scopic algae (Heal and Felton, 1970), and polyphagous, during the Iron Age. Their last meals contained 66
pest arthropods may feed on more than 300 species of different plant taxa (Godwin, 1960; King, 1966), many
crops and wild plants. The number of food plants eaten of which are nowadays considered as cosmopolitan
by humans is not far from the figures shown in Table I. weeds. Before the invention of agriculture, in the Paleo-
Domestic and wild ungulates may show a copious lithic Age, humans were hunter-gatherers, and probably
range of food species but they focus on a few, preferred had a better knowledge of the variety of edible wild
plants. A number of less palatable species are used only plants than modern people. This knowledge, however,
in time of food scarcity. Studies performed in western has slowly been lost since the Neolithic and, in present
Argentina by M. B. Kufner and S. Monge showed that times, is still lost after one or two generations of accul-
the rodent Lagostomus maximus increases the variety of turation in aboriginal communities (Plotkin, 1993). The
its food sources in degraded habitats and during process of ‘‘civilization’’ goes hand in hand with the
droughts. loss of knowledge, as well as with the abandonment of
traditional crop varieties and the habit of gathering wild
plants. But at the same time, new cultivars, coming
A. Standards of Consumption from distant countries, are constantly increasing the
On an individual basis, people use a small number of variety of foods. A recent case is that of the kiwi fruit
plant items per day, perhaps between 10 and 20 species (Actinidia deliciosa), which originated in China and
or products. A normal diet includes common vegeta- then was renamed, cultivated, and popularized in New
bles, fruits, seeds (in the form of flour or oil), roots, Zealand. The roots of the ahipa (Pachyrhizus ahipa) and
sugar, beverages (beer, wine, colas), condiments, teas, jı́cama (P. erosus), of Central American origin, have
and herbals. The number of plant species normally used become increasingly popular in the United States and
by an individual over a year, however, is about 100, Southeast Asia, especially the latter species, which has
although this is limited by the number of edible plant a similar texture and flavor to the bamboo shoots and
items commonly offered by popular markets and super- is used by Asian food restaurants in Western countries
markets. Taking into account all the variety of greens, (National Research Council, 1989; Brücher, 1989). Rice
 EDIBLE PLANTS 377

(Oryza sativa), of Asian origin, is at present the most Europe has conserved people’s knowledge of gastro-
popular staple in warm countries of South America, nomic matters. From the botanical point of view, the
while the South American potato (Solanum tuberosum) United Kingdom is probably the best-known country
has become ‘‘mandatory’’ in the European cuisine. in the world. If we compare the floristic list compiled
by Martin in 1976 with Kunkel’s list of food plants,
and discard the exotic species, hybrids, and other sub-
II. THE DIVERSITY OF FOOD PLANTS specific taxa, as well as plants used only during famine
times, we can verify that out of 1503 species considered,
No one has compiled a complete record of edible plants 350 are edible. In other words, 23% of the British flora
for the entire world. The Food and Agriculture Organi- is edible. Thus, we have two estimates of the possible
zation (FAO), part of the United Nations, publishes an richness of edible vascular plants—10 and 23%—and
annual report of the production of the commercially they represent between 27,000 and 62,000 species, re-
most important foods. This list includes about a hun- spectively, based on the 270,000 known at present.
dred species of plants. In The Oxford Book of Food Plants Because the description of the world flora has not been
(Nicholson et al., 1969), the number increases to 389 completed yet, the final list of comestibles will probably
species distributed among 81 plant families. These are increase in the future.
both locally and widely known cultivated plants. Duke By comparison, less than 2% of the Central American
(1992) estimated that North American Indians ate 1112 flora is eatable, based on the list prepared by Duke
plant species. This figure is set at 1886 species according (1992). Possible explanations for this remarkable differ-
to Moerman (1998). More than 3000 edible species are ence are: (1) greater taxonomic ignorance and/or less
carefully listed and commented on in the voluminous exploration of the natural resources—because the flora
book ‘Cornucopia’, compiled by Facciola (1990), but in of Central America is much richer than the flora of
its preface Noel D. Vietmeyer suggests that there are Britain, humans may have concentrated on fewer, more
about 20,000 edible species across the world. Probably, abundant and profitable plants, and disregarded the less
the most complete inventory is Kunkel’s (1984) book, useful ones; and (2) widespread loss of cultural heritage
which lists roughly 12,560 species from 3100 genera and environmental knowledge following the conquest
belonging to about 400 families of flowering plants and and colonization by European countries.
ferns. This list, however, is being constantly enriched
by the contribution of many ethnobotanical studies.
The proportion of edible plant species in slightly
A. The Most Prolific Taxa
disturbed communities is variable. In the Sonoran De- A first, rough estimation at higher taxonomic ranks
sert it is about 15%. Ona Indians from Tierra del Fuego indicates that the proportions of edible species are quite
made use of at least 6% of this island flora, whereas similar to the proportions of ‘‘common’’ (edible and
the Chácobo Indians, in the Bolivian Amazon, use 21% nonedible species) species present in the plant king-
of their surrounding flora. Medium to highly disturbed dom. The right-hand column in Table II is based on a
communities may contain similar or higher proportions random sample of 1790 food plants appearing in Kun-
of edible species for human consumption. For example, kel (1984).
in western Uruguay the proportion is 17%, in south- If the property of being eatable or palatable were
western Córdoba province (Argentina) it is 19%, in the
outskirts of Havana (Cuba) it is 33%, in swidden (slash-
and-burn) fields of northern India it is 43%, and in
TABLE II
experimental fields in Saskatchewan (Canada) it may
reach 61% of all wild plants. Yet studies like these do A Comparison between Common and Edible Species in
Higher Taxonomic Groups (Figures Represent Percentages of
not necessarily reveal the actual possibilities offered by Their Respective Totals)
nature, but rather the knowledge of informants and/
or the perspicacity, experience, and field-work time Common species Edible species
employed by the investigators. According to the esti- Taxonomic group (n ⫽ 270,000) (n ⫽ 1790)
mate that about 10% of any flora represents food re- Pterydophyta 3.9 1.9
sources, then 10%, or 27,000, of the 270,000 species Gymnospermae 0.3 1.0
of plants already recognized by world botanists should Dicotiledoneae 69.9 75.5
be edible. Monocotiledoneae 25.9 21.6
Since historical times, because of written testimony,
378 EDIBLE PLANTS

TABLE III There is no clear relation among the ratios of number

A Ranking of the Abundance of Genera per Plant Family of species per genus that allows us to differentiate edible
from common species. Among families with the lowest
Common species Edible species
ratios are the Asclepiadaceae (8.0), Cruciferae (8.6),
Compositae (Asteraceae) Compositae and Rutaceae (10.0). Families that are richer in species
Orchidaceae Leguminosae per genus are the Begoniaceae (255.0), Aizoaceae
Leguminosae (Fabaceae, Mimosaceae) Gramineae (208.3), and Eriocaulaceae (92.3), yet they show no
Gramineae (Poaceae, Bambusaceae) Cactaceae evidence of having experienced a process of selection,
Rubiaceae Umbelliferae that is, of ‘‘proclivity’’ or ‘‘rejection’’ by humans, that
Cruciferae (Brassicaceae) Palmae
would have led them to speciate toward palatability or
Umbelliferae (Apiaceae) Rubiaceae
distastefulness.
Euphorbiaceae Labiatae
Of the 389 more frequently cultivated species consid-
Liliaceae Euphorbiaceae
ered by Nicholson et al. (1969), the ranking goes as
Asclepiadaceae Cruciferae
follows: Rosaceae (13.3% of total species), Leguminosae
(8.5%), Gramineae (6.4%), Compositae (5.9%), Umbel-
Acanthaceae Rosaceae
liferae (5.4%), and Cruciferae (5.1%). They are followed
Labiatae (Lamiaceae) Myrtaceae
by Palmae, Cucurbitaceae, Rutaceae, Alliaceae, Cheno-
Palmae (Arecaceae) Araceae
podiaceae, Dioscoreaceae, Annonaceae, Ericaceae,
Scrophulariaceae Apocynaceae
Grossulariaceae, and 66 less prolific families. Kunkel
Rutaceae Moraceae
(1984) states that the Rosaceae is the richest family
among food plants. The analysis of a sample of 6222
items from his list confirms this assessment. Rosaceae
appears at the top of the list, comprising 5.8% of the
randomly distributed among the different taxa, then it cases, insofar as Leguminosae are split into Fabaceae
would be predictable that the most numerous families of (4th place), Mimosaceae (6th place), and Caesalpina-
plants would contain a higher number of edible species ceae (82nd place). On the contrary, if the latter three
(Table III). This relation seems to be valid since many families are considered as a unit, the Leguminosae stand
of the most prolific families are also among the most in first place, comprising 6.7% of the sample. The rank
productive in edible plants. This is the case with the of the first 30 families is shown in Table IV.
Compositae (Asteraceae), Leguminosae (Fabaceae),
Gramineae (Poaceae), Euphorbiaceae, and Rubiaceae,
which occupy the top positions in the ranking of both
B. Edible Parts
common species and edible species. The most numer- Some plant genera are extremely abundant in edible
ous of all plant families, the Orchidaceae, however, has species and may show particular tendencies toward a
few edibles. Among the most suggestive cases is the given kind of food (Table V). For example, all of the
number of genera in the Cactaceae family, which ap- 205 species of Rubus appearing in Kunkel’s list provide
pears in 4th place for edibles but is 31st in the rank of edible fruits. Among them, there are three species whose
common plants. leaves are also used as tea. Similarly, the 80 or more

TABLE IV
A Ranking of the Abundance of Edible Species in the 30 Most Prolific Familiesa

1. Rosaceae 9. Rubiaceae 17. Polygonaceae 25. Caesalpiniaceae

2. Compositae (Asteraceae) 10. Myrtaceae 18. Palmae (Arecaceae) 26. Annonaceae
3. Dioscoreaceae 11. Solanaceae 19. Ericaceae 27. Zingiberaceae
4. Fabaceae 12. Cactaceae 20. Rutaceae 28. Vitaceae
5. Liliaceae 13. Gramineae (Poaceae) 21. Umbelliferae (Apiaceae) 29. Araceae
6. Mimosaceae 14. Fagaceae 22. Sapotaceae 30. Cucurbitaceae
7. Moraceae 15. Euphorbiaceae 23. Guttiferae (Clusiaceae)
8. Ebenaceae 16. Cruciferae (Brassicaceae) 24. Asclepiadaceae

a
The richest family of common edible and nonedible species, the Orchidaceae, appears in 45th place.
 EDIBLE PLANTS 379
TABLE V
The Most Prolific Genera of Food Plants

Genus Family No. of food species Total No. of species % food species

1. Rubus Rosaceae 205 2500–3000 7–8

2. Ficus Moraceae 137 700 20
3. Dioscorea Dioscoreaceae 110 600 18
4. Solanum Solanaceae 100 1400–1700 6–7
5. Acacia Leguminosae 80 800 10
6. Eugenia Myrtaceae 79 800 10
7. Diospyros Ebenaceae 69 200 35
8. Garcinia Guttiferae 68 400 17
9. Quercus Fagaceae 67 470–1000 7–14
10. Vaccinium Ericaceae 66 300–400 17–22
11. Passiflora Passifloraceae 58 500 12
12. Opuntia Cactaceae 52 250 21

species of Prunus provide edible fruits, as also occurs An analysis of the data compiled by Duke (1972)
with Rosa spp. and Ribes spp. The majority of Piper for Central America indicates that 85% of the plant
species are used as black or white pepper or as a spice species are used for a single purpose, 10% have two
for curries. Rumex provides 44 species with leaves used uses, 4% have three uses, and 1% have four uses (leaves,
as vegetables and 3 species with edible roots. Of the flowers, fruits, and seeds). A similar analysis of the 350
100 edible species of Solanum, 59 are used only for edible species of the native British flora yields slightly
their fruits, 20 species only for their tubers, 14 for both different proportions: 78%, 19%, ⬍3%, and ⬍1% for
fruits and leaves, 6 species only for their leaves, and a one, two, three, and four purposes, respectively. One
single species exclusively for its seeds. of the exceptional cases of variability of uses is that of

TABLE VI
An Estimate of Food Usage (as Percentages of Regional Totals) from Different Sources

World flora World flora Panama Isthmus United Kingdom Andes Cambodia Botswana
(Facciola, 1990) (Kunkel, 1984)a (Duke, 1972) (Martin, 1976) (NRC, 1989) (Ito, 1969) (Campbell, 1986)

Leavesb 21.8 28.9 20.6 46.8 7.6 22.8 16.2

Fruits 19.6 30.5 37.4 9.5 61.4 29.9 33.3
Seeds 13.9 13.2 17.5 10.1 10.6 17.0 8.1
Condiments, flavorings 11.5 6.2 3.2 6.9 6.1 6.5 0.0
Tea, herbals 9.5 2.9 1.6 7.6 0.0 3.1 4.0
Beverages 7.0 0.8 6.0 0.0 2.3 1.7 4.0
Flowers, capers 6.7 4.0 4.1 4.8 0.0 9.2 1.0
Rootsc 5.6 8.7 6.3 12.6 12.1 7.5 26.3
Sapsd 4.2 3.9 2.2 0.6 0.0 2.0 7.1
Barks 0.2 0.9 1.0 1.1 0.0 0.3 0.0
No. of species 3000 1790 182 350 98 186 77
No. of items 6311 2442 336 476 132 294 99
(multiple uses)

a
A more detailed analysis of food usages appears in Table VIII.
b
Including stems, sprouts, and meristems.
c
Including bulbs and rhizomes.
d
Including gums, latex, sugars, and masticatories.
380 EDIBLE PLANTS

TABLE VII
The Distribution of Food Plants by Growth Form in Different Geographic Regionsa

Ethiopian Palearctic
Growth Total No. Percentages Nearctic Neotropical (Africa S. of (Eurasia and
form of spp. (from totals) (N. America) (C. & S. America) Indomalayan Australian the Sahara) N. Africa)

Trees 504 25.9 14.3 24.9 33.9 45.1 35.4 9.6

Shrubs 452 23.2 31.1 31.6 20.0 17.7 16.5 20.0
Herbs 787 40.4 51.2 23.7 33.9 32.4 38.8 66.5
Vines 203 10.4 3.4 19.8 12.1 4.9 9.3 3.9
Totals 1946 앑100.0 12.2 22.3 25.4 5.2 16.6 18.2

a
The sample includes 1790 species. Because, a number of species are shared between two or more regions, the total number of items
classified increases to 1946. The third column, as well as the bottom row, are percentages of the total number of species considered. The
remaining columns are percentages calculated from their respective regional subtotals.

hops (Humulus lupulus). Its leaves, roots, flowers, and Palearctic shows a significantly greater proportion of
bark may be used as food and as condiment. The pump- species that provide edible leaves, stems, and sprouts
kin (Cucurbita moschata) provides fruits, seeds, flowers, than the other regions. The Australian region is charac-
young leaves, and shoots for human consumption. terized by a greater proportion of edible seeds, and the
It is clear from Table VI that some kinds of food are Neotropics by its abundance of fruit species. Of course,
scarcely used, such as bark, flowers, sap, and liquorice. these differences were derived from the sample analyzed
In contrast, leaves (including stems, sprouts, seedlings, by us. For instance, the appearance of zero values for
and shoots) and fruits seem to be the most preferred beverages from the Australian and Palearctic regions
food. does not mean that there are no species of this kind in
their floras; they were simply not registered in our sam-
ple of 1790 species. On the contrary, the high propor-
III. GEOGRAPHIC PATTERNS OF tion of edible fruits in the Neotropical region is repeat-
FOOD PLANTS edly verified in ethnobotanical studies performed in
different countries of Central and South America. These
On the basis of a sample of 1790 species from Kunkel’s contrasts may be attributed to differential characteris-
list of food plants, it appears that edible herbs are more tics of seed dispersal evolution within their plant com-
numerous than trees, shrubs, and vines. ‘‘Vines’’ include munities, as well as to prevailing cultural trends in the
all the climbing, creeping, and epiphytic plants. Table use of natural resources. The possibility of ethnobota-
VII shows that in decreasing order of species richness, nists showing biased attention toward particular kinds
the Indomalayan regions appear first, followed by the of food should not be discarded.
Neotropical, Palearctic, Ethiopian, Nearctic, and Aus-
tralian (or Australasian) regions. By means of a chi-
square test, at a significance level P ⬍ 0.05, the Nearctic IV. ARE EDIBLE WEEDS, WEEDS?
and Australian regions show greater, and the Palearctic
lower, proportions of food trees than expected. The The habit of gathering wild food plants has not been
proportion of edible shrubs does not vary significantly totally lost. E. R. Spencer maintained that ‘‘any plant is
among regions, although at a P ⬍ 0.1 the Neotropics a weed if it insists upon growing where the husbandman
seem to have a higher proportion than the rest of the wants another plant to grow. It is a plant out of place
world. The Palearctic region shows a higher and the in the eye of man; in the nice eye of nature it is very
Neotropics a lower proportion of herbs, while the latter much in place.’’ Many of our dearest crops, however,
region is richer in vines (P ⬍ 0.05). In contrast, the have originated from weeds. In the course of time, hu-
Northern Hemisphere (Palearctic and Nearctic regions) mans learned how to profit from them. Oats (Avena
shows a significantly lower proportion of vines than sativa), foxtail millet (Setaria italica derived from S.
the Southern Hemisphere. viridis), chicory (Cichorium intybus), pak choi (Brassica
According to biogeographic regions (Table VIII), the rapa), spinach beet (Beta vulgaris), and many more
 EDIBLE PLANTS 381
TABLE VIII
A Sample of 1790 Species used in 2442 ways, Classified by Types of Food in Different Regions (Figures Are Percentages of
Regional Totals)

Nearctic Neotropical Indomalayan Australian Ethiopian Palearctic

Leavesa 24.3 14.3 30.0 25.0 27.3 48.0

Fruits 28.3 52.5 31.9 14.1 27.3 14.4
Seeds 12.8 11.7 13.7 28.9 13.3 10.0
Condiments, flavorings 3.0 3.9 8.2 2.3 6.4 8.7
Tea, herbals 4.9 2.3 2.2 4.7 2.2 3.6
Beverages 1.0 2.8 0.3 0.0 0.2 0.0
Flowers, capers 3.3 2.7 4.8 1.6 5.4 4.2
Rootsb 15.8 7.6 5.8 8.6 9.1 9.1
Sapsc 4.6 2.0 2.0 13.3 8.1 1.7
Barks 2.0 0.4 1.1 1.6 0.7 0.2
No. of items 304 487 643 128 407 471

a
Including stems, sprouts or shoots, and meristems.
b
Including bulbs and rhizomes.
c
Including gums, latex, sugars, and masticatories.

species appeared originally as invaders in ancient culti- 15,000 species of food plants are recorded and this
vated fields. Furthermore, several cosmopolitan figure is constantly growing. Yet most of the world is
‘‘weeds,’’ such as dandelion (Taraxacum officinale), gar- fed with about 20 crops. As has been pointed out by
den rocket (Eruca vesicaria), common purslane (Portu- Facciola (1990), 8000 cultivars of apples have been
laca oleracea), and shepherd’s purse (Capsella bursa- developed by humans, but only a handful are available
pastoris), are nowadays cultivated for the specialty in supermarkets.
food market.
After analyzing a set of 22,521 species of plants in- See Also the Following Articles
habiting natural ecosystems of North and South
America, we concluded that 11.3% were edible. In an- AGRICULTURE, TRADITIONAL • DOMESTICATION OF CROP
PLANTS • PLANT BIODIVERSITY, OVERVIEW
other sample of 1264 species from seminatural commu-
nities in the temperate Neotropical region, edibles were
20.3% of the total. But if only weeds are considered
(2455 widely spread species), the proportion mounts
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