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Edible Plants
Edible Plants Eduardo H Rapoport and Barbara S Drausal, Universidad Nacional del Comahue, Bariloche, Argentina r 2013 Elsevier Inc. All rights reserved.
Glossary Cultivar Cultivated variety or genetic strain of a domesticated food plant. Domesticate Plant that has been selected by humans and adapted for use as a food crop, nutrient, fiber, or for other purposes.
Food Habits Animals, whether terrestrial or marine, have limitations with respect to the variety of species they consume. They depend on what nature offers in the place where each animal lives. Since the geographic ranges of species are relatively widespread, the individuals of a given animal species may vary their food resources in different 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 ingested by an individual or by an entire population. Domestic as well as wild herbivores may eat a wide variety of food items, but they have clear preferences for particular plant species. Some ungulates are capable of selecting the most nutritious individual plants among those of the same species. They select forage mainly by smell, and secondarily by taste. Volatile substances in the plants may either inhibit or attract foragers, and are largely responsible for their palatability. According 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 and climate. Rapid growth in plants is correlated with high nutritive quality. Similar conclusions were reported by Gardarsson and Moss (1970) in a study of food selection by the Icelandic ptarmigan (Lagopus mutus). This bird consumed leaves and flowers of 8, 11, 10, and 11 species in summer, autumn, winter, and spring, respectively. Table 1
Ethnobotany Study of the variety, natural history, and characteristics of the plants used by human cultures.
Similarly, the European hare (Lepus europaeus) in northwestern Patagonia makes use of 17–21 species of plants in a given season out of a total of 28 species that it consumes over the year. Table 1 provides a short sample of the variety of food consumed by different herbivorous and omnivorous mammals. The case of the Soay sheep was included to show how a domestic herbivore may restrict its diet in a species-poor environment. Of course, the range of foods ingested by other animals may vary widely. Monophagous insects restrict themselves to only one plant species, soil amoebae (Acanthamoeba) normally ingest five species of microscopic algae (Heal and Felton, 1970), and polyphagous, pest arthropods may feed on more than 300 species of crops and wild plants. The number of food plants eaten by humans is not far from the figures shown in Table 1. Domestic and wild ungulates may show a copious range of food species but they focus on a few, preferred plants. A number of less palatable species are used only in time of food scarcity. Studies performed in western Argentina by Kufner and Monge showed that the rodent Lagostotmus maximus increases the variety of its food sources in degraded habitats and during droughts.
Standards of Consumption On an individual basis, people use a small number of plant items per day, perhaps between 10 and 20 species or products.
The number of food plants consumed annually by different mammal species
Mammal species
Common name
Number of plant species
Source
Alouatta fusca Ateles spp. Bos Taurus Copra hircus Cebus paella Cervus elaphus Chiropotes satanas Ctenomys mendocinus Lagidium viscacia Lama guanicoe Lepus europaeus Ovis aries Pithecia pithecia
Brown howler monkey, SE Brazil Spider monkey, Panama Cattle, NW Patagonia Goat, Mendoza, Argentina Capuchin monkey, SE Brazil European red deer, NW Patagonia Monkey, Venezuela Tuco-tuco, Argentina Vizcacha de la sierra, Argentina Guanaco, Mendoza, Argentina European hare, NW Patagonia Soay sheep, St. Kilka Island, UK Monkey, Venezuela
52 14 23 76 73 34 29 28 21 47 28 B12 25
Galetti et al. (1994) Milton (1981) Relva (1998) Dalmasso et al. (1995) Galetti and Pedroni (1994) Relva (1998) Kinsey and Norconk (1993) Madoeri (1993) Galende and Grigera (1998) Candia and Dalmasso (1995) Galende and Grigera (1998) Gwynne and Boyd (1970) Kinsey and Norconk (1993)
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A normal diet includes common vegetables, fruits, seeds (in the form of flour or oil), roots, sugar, beverages (beer, wine, colas), condiments, teas, and herbals. The number of plant species normally used by an individual over a year, however, is about 100, although this is limited by the number of edible plant items commonly offered by popular markets and supermarkets. Taking into account all the variety of greens, vegetables, fruits, grains, nuts, and condiments in an exceptionally well-provisioned supermarket, the figure (including different varieties and brands) may rise to 600, according to Duke (1992). The stomach contents of two mummies that were found well-preserved in Danish bogs provided interesting information about the gastronomic habits of people during the Iron Age. Their last meals contained 66 different plant taxa (Godwin, 1960; King, 1966), many of which are nowadays considered as cosmopolitan weeds. Before the invention of agriculture, in the Paleolithic Age, humans were huntergatherers, and probably had a better knowledge of the variety of edible wild plants than modern people. This knowledge, however, has slowly been lost since the Neolithic and, in present times, is still lost after one or two generations of acculturation in aboriginal communities (Plotkin, 1993). The process of civilization goes hand in hand with the 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 from distant countries, are constantly increasing the variety of foods. A recent case is that of the kiwi fruit (Actinidia deliciosa), which originated in China and then was renamed, cultivated, and popularized in New Zealand. The roots of the ahipa (Pachyrhizus ahipa) and jicama (P. erosus), of Central American origin, have become increasingly popular in the US and Southeast Asia, especially the latter species, which has a similar texture and flavor to bamboo shoots and is used by Asian food restaurants in Western countries (National Research Council, 1989; Brucher, 1989). Rice (Oryza sativa), of Asian origin, is at present the most popular staple in warm countries of South America, whereas the South American potato (Solanum tuberosum) has become mandatory in European cuisine.
The Diversity of Food Plants No one has compiled a complete record of edible plants for the entire world. The Food and Agriculture Organization (FAO), part of the United Nations, publishes an annual report of the production of the commercially most important foods. This list includes about a hundred species of plants. In The Oxford Book of Food Plants (Nicholson et al., 1969), the number increases to 389 species distributed among 81 plant families. These are both locally and widely known cultivated plants. Duke (1992) estimated that North American Indians ate 1112 plant species. This figure is set at 1886 species according to Moerman (1998). More than 3000 edible species are carefully listed and commented on in the voluminous book Cornucopia, compiled by Facciola (1990), but in its preface Noel D. Vietmeyer suggests that there are about 20,000 edible species across the world. Probably, the most complete inventory is Kunkel’s (1984) book, which lists approximately 12,560
species from 3100 genera belonging to about 400 families of flowering plants and ferns. This list, however, is being constantly enriched by the contribution of many ethnobotanical studies. The proportion of edible plant species in slightly disturbed communities is variable. In the Sonoran Desert it is about 15%. Ona Indians from Tierra del Fuego made use of at least 6% of this island flora, whereas the Cha´cobo Indians in the Bolivian Amazon use 21% of their surrounding flora. Medium to highly disturbed communities may contain similar or higher proportions of edible species for human consumption. For example, in western Uruguay the proportion is 17%, in southwestern Co´rdoba province (Argentina) it is 19%, in the outskirts of Havana (Cuba) it is 33%, in swidden (slash-andburn) fields of northern India it is 43%, and in experimental fields in Saskatchewan (Canada) it may reach 61% of all wild plants. Yet studies like these do not necessarily reveal the actual possibilities offered by nature, but rather the knowledge of informants or the perspicacity, experience, and fieldwork time employed by the investigators. According to the estimate that about 10% of any flora represents food resources, then 10%, or 27,000, of the 270,000 species of plants already recognized by world botanists should be edible. Since historical times, because of written testimony, Europe has conserved people’s knowledge of gastronomic matters. From the botanical point of view, the UK is probably the bestknown country 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-specific taxa, as well as plants used only during famine times, we can verify that out of 1503 species considered, 350 are edible. In other words, 23% of the British flora is edible. Thus, we have two estimates of the possible richness of edible vascular plants – 10% and 23% – and they represent between 27,000 and 62,000 species, respectively, based on the 270,000 known at present. Because the description of the world flora has not been completed yet, the final list of comestibles will probably increase in the future. By comparison, less than 2% of the Central American flora is eatable, based on the list prepared by Duke (1992). Possible explanations for this remarkable difference are: (1) greater taxonomic ignorance or less exploration of the natural resources – because the flora of Central America is much richer than the flora of Britain, humans may have concentrated on fewer, more abundant, and profitable plants, and disregarded the less useful ones; and (2) widespread loss of cultural heritage and environmental knowledge following the conquest and colonization by European countries.
The Most Prolific Taxa A first, rough estimation at higher taxonomic ranks indicates that the proportions of edible species are quite similar to the proportions of common (edible and nonedible species) species present in the plant kingdom. The right-hand column in Table 2 is based on a random sample of 1790 food plants appearing in Kunkel (1984). If the property of being eatable or palatable were randomly distributed among the different taxa, then it would be
Edible Plants
Table 2 A comparison between common and edible Species in higher taxonomic groups (figures represent percentages of their respective totals) Taxonomic group
Common species (n ¼ 270,000)
Edible species (n ¼ 1790)
Pterydophyta Gymnospermae Dicotiledoneae Monocotiledoneae
3.9 0.3 69.9 25.9
1.9 1.0 75.5 21.6
predictable that the most numerous families of plants would contain a higher number of edible species (Table 3). This relation seems to be valid since many of the most prolific families are also among the most productive in edible plants. This is the case with the Compositae (Asteraceae), Leguminosae (Fabaceae), Gramineae (Poaceae), Euphorbiaceae, and Rubiaceae, which occupy the top positions in the ranking of both common species and edible species. The most numerous of all plant families, the Orchidaceae, however, has few edibles. Among the most suggestive cases is the number of genera in the Cactaceae family, which appears in the fourth place for edibles but is the 31st in the rank of common plants. There is no clear relation among the ratios of number of species per genus that allows us to differentiate edible from common species. Among families with the lowest ratios are the Asclepiadaceae (8.0), Cruciferae (8.6), and Rutaceae (10.0). Families that are richer in species per genus are the Begoniaceae (255.0), Aizoaceae (208.3), and Eriocaulaceae (92.3), yet they show no evidence of having experienced a process of selection, that is, of proclivity or rejection by humans, that would have led them to speciate toward palatability or distastefulness. Of the 389 more frequently cultivated species considered by Nicholson et al. (1969), the ranking goes as follows: Rosaceae (13.3% of total species), Leguminosae (8.5%), Gramineae (6.4%), Compositae (5.9%), Umbelliferae (5.4%), and Cruciferae (5.1%). They are followed by Palmae, Cucurbitaceae, Rutaceae, Alliaceae, Chenopodiaceae, Dioscoreaceae, Annonaceae, Ericaceae, Grossulariaceae, and 66 less prolific families. Kunkel (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 cases, insofar as Leguminosae are split into Fabaceae (fourth place), Mimosaceae (sixth place), and Caesalpinaceae (82nd place). On the contrary, if the latter three families are considered as a unit, the Leguminosae stand in first place, comprising 6.7% of the sample. The rank of the first 30 families is shown in Table 4.
Table 3
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A ranking of the abundance of genera per plant family
Common species
Edible species
Compositae (Asteraceae) Orchidaceae Leguminosae (Fabaceae, Mimosaceae) Gramineae (Poaceae, Bambusaceae) Rubiaceae Cruciferae (Brassicaceae) Umbelliferae (Apiaceae) Euphorbiaceae Liliaceae Asclepiadaceae Acanthaceae Labiatae (Lamiaceae) Palmae (Arecaceae) Scrophulariaceae Rutaceae
Compositae Leguminosae Gramineae Cactaceae Umbelliferae Palmae Rubiaceae Labiatae Euphorbiaceae Cruciferae Rosaceae Myrtaceae Araceae Apocynaceae Moraceae
Table 4 A ranking of the abundance of edible species in the 30 most prolific familiesa 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30.
Rosaceae Compositae (Asteraceae) Dioscoreaceae Fabaceae Liliaceae Mimosaceae Moraceae Ebenaceae Rubiaceae Myrtaceae Solanaceae Cactaceae Gramineae (Poaceae) Fagaceae Euphorbiaceae Cruciferae (Brassicaceae) Polygonaceae Palmae (Arecaceae) Ericaceae Rutaceae Umbelliferae (Apiaceae) Sapotaceae Guttiferae (Clusiaceae) Asclepiadaceae Caesalpiniaceae Annonaceae Zingiberaceae Vitaceae Araceae Cucurbitaceae
a
Edible Parts
The richest family of common edible and nonedible species, the Orchidaceae, appears in 45th place.
Some plant genera are extremely abundant in edible species and may show particular tendencies toward a given kind of food (Table 5). For example, all of the 205 species of Rubus appearing in Kunkel’s list provide edible fruits. Among them, there are three species whose leaves are also used as tea. Similarly, the 80 or more species of Prunus provide edible fruits, as also occurs with Rosa spp. and Ribes spp. The majority of Piper species are
used as black or white pepper or as a spice for curries. Rumex provides 44 species with leaves used as vegetables and three species with edible roots. Of the 100 edible species of Solanum, 59 are used only for their fruits, 20 species only for their tubers, 14 for both fruits and leaves, six species only for their leaves, and a single species exclusively for its seeds.
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Table 5
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The most prolific genera of food plants
Genus
Family
Number of food species
Total number of species
% food species
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
Rosaceae Moraceae Dioscoreaceae Solanaceae Leguminosae Myrtaceae Ebenaceae Guttiferae Fagaceae Ericaceae Passifloraceae Cactaceae
205 137 110 100 80 79 69 68 67 66 58 52
2500–3000 700 600 1400–1700 800 800 200 400 470–1000 300–400 500 250
7–8 20 18 6–7 10 10 35 17 7–14 17–22 12 21
Ruibus Ficus Dioscorea Solarium Acacia Eugenia Diospyros Garcinia Quercus Vaccinium Passiflora Opuntia
Table 6
An estimate of food usage (as percentages of regional totals) from different sources World flora (Facciola, 1990)
Leavesb Fruits Seeds Condiments, flavorings Tea, herbals Beverages Flowers, capers Rootsc Sapsd Barks Number of species Number of items (multiple uses)
World flora (Kunkel, 1984)a
Panama Isthmus United Kingdom (Duke, 1990) (Martin, 1976)
Andes (NRC, 1989)
Cambodia (Ito, 1969)
Botswana (Campbell, 1986)
21.8 19.6 13.9 11.5
28.9 30.5 13.2 6.2
20.6 37.4 17.5 3.2
46.8 9.5 10.1 6.9
7.6 61.4 10.6 6.1
22.8 29.9 17.0 6.5
16.2 33.3 8.1 0.0
9.5 7.0 6.7 5.6 4.2 0.2 3000
2.9 0.8 4.0 8.7 3.9 0.9 1790
1.6 6.0 4.1 6.3 2.2 1.0 182
7.6 0.0 4.8 12.6 0.6 1.1 350
0.0 2.3 0.0 12.1 0.0 0.0 98
3.1 1.7 9.2 7.5 2.0 0.3 186
4.0 4.0 1.0 26.3 7.1 0.0 77
6311
2442
336
476
294
99
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a
A more detailed analysis of food usages appears in Table 8. Including stems, sprouts, and meristems. c Including bulbs and rhizomes. d Including gums, latex, sugars, and masticatories. b
An analysis of the data compiled by Duke (1972) for Central America indicates that 85% of the plant species are used for a single purpose, 10% have two uses, 4% have three uses, and 1% have four uses (leaves, flowers, fruits, and seeds). A similar analysis of the 350 edible species of native British flora yields slightly different proportions: 78%, 19%, o3%, and o1% for one, two, three, and four purposes, respectively. One of the exceptional cases of variability of uses is that of hops (Humulus lupulus). Its leaves, roots, flowers, and bark may be used as food and as condiment. The pumpkin (Cucurbita moschata) provides fruits, seeds, flowers, young leaves, and shoots for human consumption. It is clear from Table 6 that some kinds of food are scarcely used, such as bark, flowers, sap, and liquorice. In contrast, leaves (including stems, sprouts, seedlings, and shoots) and fruits seem to be the most preferred food.
Geographic Patterns of Food Plants On the basis of a sample of 1790 species from Kunkel’s list of food plants, it appears that edible herbs are more numerous
than trees, shrubs, and vines. Vines include all the climbing, creeping, and epiphytic plants. Table 7 shows that in decreasing order of species richness, the Indomalayan regions appear first, followed by the Neotropical, Palearctic, Ethiopian, Nearctic, and Australian (or Australasian) regions. By means of a chi-square test, at a significance level Po.05, the Nearctic and Australian regions show greater, and the Palearctic lower, proportions of food trees than expected. The proportion of edible shrubs does not vary significantly among regions, although at a Po.1 the Neotropics seem to have a higher proportion than the rest of the world. The Palearctic region shows a higher and the Neotropics a lower proportion of herbs, whereas the latter region is richer in vines (Po.05). In contrast, the Northern Hemisphere (Palearctic and Nearctic regions) shows a significantly lower proportion of vines than the Southern Hemisphere. According to biogeographic regions (Table 8), the Palearctic shows a significantly greater proportion of species that provide edible leaves, stems, and sprouts than the other regions. The Australian region is characterized by a greater
Edible Plants
Table 7
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The distribution of food plants by growth form in different geographic regionsa
Growth form
Total number of spp.
Percentages (from totals)
Nearctic (North America)
Neotropical (C. & South America)
Indomalayan
Australian
Ethiopian (Africa S. of the Sahara)
Palearctic (Eurasia and North Africa)
Trees Shrubs Herbs Vines Totals
504 452 787 203 1946
25.9 23.2 40.4 10.4 B100.0
14.3 31.1 51.2 3.4 12.2
24.9 31.6 23.7 19.8 22.3
33.9 20.0 33.9 12.1 25.4
45.1 17.7 32.4 4.9 5.2
35.4 16.5 38.8 9.3 16.6
9.6 20.0 66.5 3.9 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.
Table 8 totals)
A sample of 1790 species used in 2442 ways, classified by types of food in different regions (figures are percentages of regional
Leavesa Fruits Seeds Condiments, flavorings Tea, herbals Beverages Flowers, capers Rootsb Sapsc Barks Number of items
Nearctic
Neotropical
Indomalayan
Australian
Ethiopian
Palearctic
24.3 28.3 12.8 3.0 4.9 1.0 3.3 15.8 4.6 2.0 304
14.3 52.5 11.7 3.9 2.3 2.8 2.7 7.6 2.0 0.4 487
30.0 31.9 13.7 8.2 2.2 0.3 4.8 5.8 2.0 1.1 643
25.0 14.1 28.9 2.3 4.7 0.0 1.6 8.6 13.3 1.6 128
27.3 27.3 13.3 6.4 2.2 0.2 5.4 9.1 8.1 0.7 407
48.0 14.4 10.0 8.7 3.6 0.0 4.2 9.1 1.7 0.2 471
a
Including stems, sprouts or shoots, and meristems. Including bulbs and rhizomes. c Including gums, latex, sugars, and masticatories. b
proportion of edible seeds, and the Neotropics by its abundance of fruit species. Of course, these differences were derived from the sample analyzed by us. For instance, the appearance of zero values for beverages from the Australian and Palearctic regions does not mean that there are no species of this kind in their floras; they were simply not registered in our sample of 1790 species. On the contrary, the high proportion of edible fruits in the Neotropical region is repeatedly verified in ethnobotanical studies performed in different countries of Central and South America. These contrasts may be attributed to differential characteristics of seed dispersal evolution within their plant communities, as well as to prevailing cultural trends in the use of natural resources. The possibility of ethnobotanists showing biased attention toward particular kinds of food should not be discarded.
Are Edible Weeds Weeds? The habit of gathering wild food plants has not been totally lost. Spencer maintained that ‘‘any plant is a weed if it insists upon growing where the husbandman wants another plant to grow. It is a plant out of place in the eye of man; in the nice eye of nature it is very much in place.’’ Many of our dearest crops, however, have originated from weeds. In the course of
time, humans learned how to profit from them. Oats (Avena sativa), foxtail millet (Setaria italica derived from S. viridis), chicory (Cichorium intybus), pak choi (Brassica rapa), spinach beet (Beta vulgaris), and many more species appeared originally as invaders in ancient cultivated fields. Furthermore, several cosmopolitan weeds, such as dandelion (Taraxacum officinale), garden rocket (Eruca vesicaria), common purslane (Portulaca oleracea), and shepherd’s purse (Capsella bursapastoris), are nowadays cultivated for the specialty food market. After analyzing a set of 22,521 species of plants inhabiting natural ecosystems of North and South America, we concluded that 11.3% were edible. In another sample of 1264 species from seminatural communities 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 to 35.6%. This demonstrates that the degree of environmental disturbance correlates with the proportion of weeds, which in turn increases the proportion of edible food resources. This should not be surprising given that 17 of the world’s 18 most aggressive weeds provide parts for human consumption. Because weeds are so numerous (more than 10,000 species cataloged) and so abundant (averaging 1.3 and 2.1 ton ha1 in a temperate and a tropical area of northwestern Patagonia and eastern Mexico, respectively; Dı´azBetancourt et al., 1999; Rapoport et al., 1998), they stand
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ambiguously as both enemies and potential benefactors of humanity. The prospects for the future of food plant diversity appear to be auspicious. Further research should be conducted to manage and profit from these varied and abundant natural resources. At present, more than 15,000 species of food plants are recorded and this figure is constantly growing. Yet most of the world is fed with about 20 crops. As has been pointed out by Facciola (1990), 8000 cultivars of apples have been developed by humans, but only a handful are available in supermarkets.
See also: Agriculture, Traditional. Domestication of Crop Plants. Plant Biodiversity, Overview
References Brucher H (1989) Useful Plants of Neotropical Origin and Their Wild Relatives. New York: Springer-Verlag. Campbell A (1986) The use of wild food plants, and drought in Botswana. Journal of Arid Environment 11: 81–91. Dı´az-Betancourt M, Ghermandi L, Ladio A, Lo´pez-Moreno IR, Raffaele E, and Rapoport EH (1999) Weeds as a source for human consumption. A comparison between tropical and temperate Latin America. Revista de Biologia Tropical 47: 329–338.
Duke JA (1972) Isthmian Ethnobotanical Dictionary. Maryland: Fulton. Duke JA (1992) Handbook of Edible Weeds. Boca Raton, FL: CRC Press. Facciola S (1990) Cornucopia. A Sourcebook of Edible Plants. Vista, CA: Kampong Publications. (A second, revised edition was published in 1998.) Gardarsson A and Moss R (1970) Selection of food by Icelandic Ptarmingan in relation to its availability and nutritive value. In: Watson A (ed.) Animal Population in Relation to Their Food Resources, pp. 47–71. Oxford: Blackwell. Godwin H (1960) The history of weed in Britain. In: Harper JL (ed.) The Biology of Weeds, pp. 1–10. Oxford: Blackwell. Heal OW and Felton MJ (1970) Soil amoeba: Their food and their reaction to microflora exudates. In: Watson A (ed.) Animal Population in Relation to Their Food Resources, pp. 145–162. Oxford: Blackwell. Ito S (1969) Economical plants and their distribution in Cambodia. Journal of Agricultural Science Tokyo University of Agriculture 13: 163–218. King LW (1966) Weeds of the World. Biology and Control. London: Leonard Hill. Klein DK (1970) Food selection by North American deer and their response to overutilization of preferred plant species. In: Watson A (ed.) Animal Population in Relation to Their Food Resources, pp. 25–46. Oxford: Blackwell. Kunkel G (1984) Plants for Human Consumption. Koenigsten, Germany: Koeltz Scientific Books. Martin WK (1976) The Concise British Flora in Colour. London: Ebury Press and Michael Joseph. Moerman DE (1998) Native American Ethnobotany. Portland, Oregon: Timber Press. National Research Council (1989) Lost Crops of the Incas. Washington, DC: National Academy Press. Nicholson BE, Harrison SG, Masefield GB, and Wallis M (1969) The Oxford Book of Food Plants. London: Oxford University Press. (A second, updated edition appeared as Vaughan JG and Geissler CA. (1997) The New Oxford Book of Food Plants: A Guide to the Fruit, Vegetables, Herbs, and Spices of the World.) Plotkin MJ (1993) Tales of a Shaman’s Apprentice. New York: Penguin Books. Rapoport EH, Ladio A, Raffaele E, Ghermandi L, and Sanz EH (1998) Malezas comestibles. Ciencia Hoy 9(49): 30–43.
Glossary Cultivar Cultivated variety or genetic strain of a domesticated food plant. Domesticate Plant that has been selected by humans and adapted for use as a food crop, nutrient, fiber, or for other purposes.
Food Habits Animals, whether terrestrial or marine, have limitations with respect to the variety of species they consume. They depend on what nature offers in the place where each animal lives. Since the geographic ranges of species are relatively widespread, the individuals of a given animal species may vary their food resources in different 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 ingested by an individual or by an entire population. Domestic as well as wild herbivores may eat a wide variety of food items, but they have clear preferences for particular plant species. Some ungulates are capable of selecting the most nutritious individual plants among those of the same species. They select forage mainly by smell, and secondarily by taste. Volatile substances in the plants may either inhibit or attract foragers, and are largely responsible for their palatability. According 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 and climate. Rapid growth in plants is correlated with high nutritive quality. Similar conclusions were reported by Gardarsson and Moss (1970) in a study of food selection by the Icelandic ptarmigan (Lagopus mutus). This bird consumed leaves and flowers of 8, 11, 10, and 11 species in summer, autumn, winter, and spring, respectively. Table 1
Ethnobotany Study of the variety, natural history, and characteristics of the plants used by human cultures.
Similarly, the European hare (Lepus europaeus) in northwestern Patagonia makes use of 17–21 species of plants in a given season out of a total of 28 species that it consumes over the year. Table 1 provides a short sample of the variety of food consumed by different herbivorous and omnivorous mammals. The case of the Soay sheep was included to show how a domestic herbivore may restrict its diet in a species-poor environment. Of course, the range of foods ingested by other animals may vary widely. Monophagous insects restrict themselves to only one plant species, soil amoebae (Acanthamoeba) normally ingest five species of microscopic algae (Heal and Felton, 1970), and polyphagous, pest arthropods may feed on more than 300 species of crops and wild plants. The number of food plants eaten by humans is not far from the figures shown in Table 1. Domestic and wild ungulates may show a copious range of food species but they focus on a few, preferred plants. A number of less palatable species are used only in time of food scarcity. Studies performed in western Argentina by Kufner and Monge showed that the rodent Lagostotmus maximus increases the variety of its food sources in degraded habitats and during droughts.
Standards of Consumption On an individual basis, people use a small number of plant items per day, perhaps between 10 and 20 species or products.
The number of food plants consumed annually by different mammal species
Mammal species
Common name
Number of plant species
Source
Alouatta fusca Ateles spp. Bos Taurus Copra hircus Cebus paella Cervus elaphus Chiropotes satanas Ctenomys mendocinus Lagidium viscacia Lama guanicoe Lepus europaeus Ovis aries Pithecia pithecia
Brown howler monkey, SE Brazil Spider monkey, Panama Cattle, NW Patagonia Goat, Mendoza, Argentina Capuchin monkey, SE Brazil European red deer, NW Patagonia Monkey, Venezuela Tuco-tuco, Argentina Vizcacha de la sierra, Argentina Guanaco, Mendoza, Argentina European hare, NW Patagonia Soay sheep, St. Kilka Island, UK Monkey, Venezuela
52 14 23 76 73 34 29 28 21 47 28 B12 25
Galetti et al. (1994) Milton (1981) Relva (1998) Dalmasso et al. (1995) Galetti and Pedroni (1994) Relva (1998) Kinsey and Norconk (1993) Madoeri (1993) Galende and Grigera (1998) Candia and Dalmasso (1995) Galende and Grigera (1998) Gwynne and Boyd (1970) Kinsey and Norconk (1993)
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A normal diet includes common vegetables, fruits, seeds (in the form of flour or oil), roots, sugar, beverages (beer, wine, colas), condiments, teas, and herbals. The number of plant species normally used by an individual over a year, however, is about 100, although this is limited by the number of edible plant items commonly offered by popular markets and supermarkets. Taking into account all the variety of greens, vegetables, fruits, grains, nuts, and condiments in an exceptionally well-provisioned supermarket, the figure (including different varieties and brands) may rise to 600, according to Duke (1992). The stomach contents of two mummies that were found well-preserved in Danish bogs provided interesting information about the gastronomic habits of people during the Iron Age. Their last meals contained 66 different plant taxa (Godwin, 1960; King, 1966), many of which are nowadays considered as cosmopolitan weeds. Before the invention of agriculture, in the Paleolithic Age, humans were huntergatherers, and probably had a better knowledge of the variety of edible wild plants than modern people. This knowledge, however, has slowly been lost since the Neolithic and, in present times, is still lost after one or two generations of acculturation in aboriginal communities (Plotkin, 1993). The process of civilization goes hand in hand with the 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 from distant countries, are constantly increasing the variety of foods. A recent case is that of the kiwi fruit (Actinidia deliciosa), which originated in China and then was renamed, cultivated, and popularized in New Zealand. The roots of the ahipa (Pachyrhizus ahipa) and jicama (P. erosus), of Central American origin, have become increasingly popular in the US and Southeast Asia, especially the latter species, which has a similar texture and flavor to bamboo shoots and is used by Asian food restaurants in Western countries (National Research Council, 1989; Brucher, 1989). Rice (Oryza sativa), of Asian origin, is at present the most popular staple in warm countries of South America, whereas the South American potato (Solanum tuberosum) has become mandatory in European cuisine.
The Diversity of Food Plants No one has compiled a complete record of edible plants for the entire world. The Food and Agriculture Organization (FAO), part of the United Nations, publishes an annual report of the production of the commercially most important foods. This list includes about a hundred species of plants. In The Oxford Book of Food Plants (Nicholson et al., 1969), the number increases to 389 species distributed among 81 plant families. These are both locally and widely known cultivated plants. Duke (1992) estimated that North American Indians ate 1112 plant species. This figure is set at 1886 species according to Moerman (1998). More than 3000 edible species are carefully listed and commented on in the voluminous book Cornucopia, compiled by Facciola (1990), but in its preface Noel D. Vietmeyer suggests that there are about 20,000 edible species across the world. Probably, the most complete inventory is Kunkel’s (1984) book, which lists approximately 12,560
species from 3100 genera belonging to about 400 families of flowering plants and ferns. This list, however, is being constantly enriched by the contribution of many ethnobotanical studies. The proportion of edible plant species in slightly disturbed communities is variable. In the Sonoran Desert it is about 15%. Ona Indians from Tierra del Fuego made use of at least 6% of this island flora, whereas the Cha´cobo Indians in the Bolivian Amazon use 21% of their surrounding flora. Medium to highly disturbed communities may contain similar or higher proportions of edible species for human consumption. For example, in western Uruguay the proportion is 17%, in southwestern Co´rdoba province (Argentina) it is 19%, in the outskirts of Havana (Cuba) it is 33%, in swidden (slash-andburn) fields of northern India it is 43%, and in experimental fields in Saskatchewan (Canada) it may reach 61% of all wild plants. Yet studies like these do not necessarily reveal the actual possibilities offered by nature, but rather the knowledge of informants or the perspicacity, experience, and fieldwork time employed by the investigators. According to the estimate that about 10% of any flora represents food resources, then 10%, or 27,000, of the 270,000 species of plants already recognized by world botanists should be edible. Since historical times, because of written testimony, Europe has conserved people’s knowledge of gastronomic matters. From the botanical point of view, the UK is probably the bestknown country 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-specific taxa, as well as plants used only during famine times, we can verify that out of 1503 species considered, 350 are edible. In other words, 23% of the British flora is edible. Thus, we have two estimates of the possible richness of edible vascular plants – 10% and 23% – and they represent between 27,000 and 62,000 species, respectively, based on the 270,000 known at present. Because the description of the world flora has not been completed yet, the final list of comestibles will probably increase in the future. By comparison, less than 2% of the Central American flora is eatable, based on the list prepared by Duke (1992). Possible explanations for this remarkable difference are: (1) greater taxonomic ignorance or less exploration of the natural resources – because the flora of Central America is much richer than the flora of Britain, humans may have concentrated on fewer, more abundant, and profitable plants, and disregarded the less useful ones; and (2) widespread loss of cultural heritage and environmental knowledge following the conquest and colonization by European countries.
The Most Prolific Taxa A first, rough estimation at higher taxonomic ranks indicates that the proportions of edible species are quite similar to the proportions of common (edible and nonedible species) species present in the plant kingdom. The right-hand column in Table 2 is based on a random sample of 1790 food plants appearing in Kunkel (1984). If the property of being eatable or palatable were randomly distributed among the different taxa, then it would be
Edible Plants
Table 2 A comparison between common and edible Species in higher taxonomic groups (figures represent percentages of their respective totals) Taxonomic group
Common species (n ¼ 270,000)
Edible species (n ¼ 1790)
Pterydophyta Gymnospermae Dicotiledoneae Monocotiledoneae
3.9 0.3 69.9 25.9
1.9 1.0 75.5 21.6
predictable that the most numerous families of plants would contain a higher number of edible species (Table 3). This relation seems to be valid since many of the most prolific families are also among the most productive in edible plants. This is the case with the Compositae (Asteraceae), Leguminosae (Fabaceae), Gramineae (Poaceae), Euphorbiaceae, and Rubiaceae, which occupy the top positions in the ranking of both common species and edible species. The most numerous of all plant families, the Orchidaceae, however, has few edibles. Among the most suggestive cases is the number of genera in the Cactaceae family, which appears in the fourth place for edibles but is the 31st in the rank of common plants. There is no clear relation among the ratios of number of species per genus that allows us to differentiate edible from common species. Among families with the lowest ratios are the Asclepiadaceae (8.0), Cruciferae (8.6), and Rutaceae (10.0). Families that are richer in species per genus are the Begoniaceae (255.0), Aizoaceae (208.3), and Eriocaulaceae (92.3), yet they show no evidence of having experienced a process of selection, that is, of proclivity or rejection by humans, that would have led them to speciate toward palatability or distastefulness. Of the 389 more frequently cultivated species considered by Nicholson et al. (1969), the ranking goes as follows: Rosaceae (13.3% of total species), Leguminosae (8.5%), Gramineae (6.4%), Compositae (5.9%), Umbelliferae (5.4%), and Cruciferae (5.1%). They are followed by Palmae, Cucurbitaceae, Rutaceae, Alliaceae, Chenopodiaceae, Dioscoreaceae, Annonaceae, Ericaceae, Grossulariaceae, and 66 less prolific families. Kunkel (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 cases, insofar as Leguminosae are split into Fabaceae (fourth place), Mimosaceae (sixth place), and Caesalpinaceae (82nd place). On the contrary, if the latter three families are considered as a unit, the Leguminosae stand in first place, comprising 6.7% of the sample. The rank of the first 30 families is shown in Table 4.
Table 3
129
A ranking of the abundance of genera per plant family
Common species
Edible species
Compositae (Asteraceae) Orchidaceae Leguminosae (Fabaceae, Mimosaceae) Gramineae (Poaceae, Bambusaceae) Rubiaceae Cruciferae (Brassicaceae) Umbelliferae (Apiaceae) Euphorbiaceae Liliaceae Asclepiadaceae Acanthaceae Labiatae (Lamiaceae) Palmae (Arecaceae) Scrophulariaceae Rutaceae
Compositae Leguminosae Gramineae Cactaceae Umbelliferae Palmae Rubiaceae Labiatae Euphorbiaceae Cruciferae Rosaceae Myrtaceae Araceae Apocynaceae Moraceae
Table 4 A ranking of the abundance of edible species in the 30 most prolific familiesa 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30.
Rosaceae Compositae (Asteraceae) Dioscoreaceae Fabaceae Liliaceae Mimosaceae Moraceae Ebenaceae Rubiaceae Myrtaceae Solanaceae Cactaceae Gramineae (Poaceae) Fagaceae Euphorbiaceae Cruciferae (Brassicaceae) Polygonaceae Palmae (Arecaceae) Ericaceae Rutaceae Umbelliferae (Apiaceae) Sapotaceae Guttiferae (Clusiaceae) Asclepiadaceae Caesalpiniaceae Annonaceae Zingiberaceae Vitaceae Araceae Cucurbitaceae
a
Edible Parts
The richest family of common edible and nonedible species, the Orchidaceae, appears in 45th place.
Some plant genera are extremely abundant in edible species and may show particular tendencies toward a given kind of food (Table 5). For example, all of the 205 species of Rubus appearing in Kunkel’s list provide edible fruits. Among them, there are three species whose leaves are also used as tea. Similarly, the 80 or more species of Prunus provide edible fruits, as also occurs with Rosa spp. and Ribes spp. The majority of Piper species are
used as black or white pepper or as a spice for curries. Rumex provides 44 species with leaves used as vegetables and three species with edible roots. Of the 100 edible species of Solanum, 59 are used only for their fruits, 20 species only for their tubers, 14 for both fruits and leaves, six species only for their leaves, and a single species exclusively for its seeds.
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Table 5
Edible Plants
The most prolific genera of food plants
Genus
Family
Number of food species
Total number of species
% food species
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
Rosaceae Moraceae Dioscoreaceae Solanaceae Leguminosae Myrtaceae Ebenaceae Guttiferae Fagaceae Ericaceae Passifloraceae Cactaceae
205 137 110 100 80 79 69 68 67 66 58 52
2500–3000 700 600 1400–1700 800 800 200 400 470–1000 300–400 500 250
7–8 20 18 6–7 10 10 35 17 7–14 17–22 12 21
Ruibus Ficus Dioscorea Solarium Acacia Eugenia Diospyros Garcinia Quercus Vaccinium Passiflora Opuntia
Table 6
An estimate of food usage (as percentages of regional totals) from different sources World flora (Facciola, 1990)
Leavesb Fruits Seeds Condiments, flavorings Tea, herbals Beverages Flowers, capers Rootsc Sapsd Barks Number of species Number of items (multiple uses)
World flora (Kunkel, 1984)a
Panama Isthmus United Kingdom (Duke, 1990) (Martin, 1976)
Andes (NRC, 1989)
Cambodia (Ito, 1969)
Botswana (Campbell, 1986)
21.8 19.6 13.9 11.5
28.9 30.5 13.2 6.2
20.6 37.4 17.5 3.2
46.8 9.5 10.1 6.9
7.6 61.4 10.6 6.1
22.8 29.9 17.0 6.5
16.2 33.3 8.1 0.0
9.5 7.0 6.7 5.6 4.2 0.2 3000
2.9 0.8 4.0 8.7 3.9 0.9 1790
1.6 6.0 4.1 6.3 2.2 1.0 182
7.6 0.0 4.8 12.6 0.6 1.1 350
0.0 2.3 0.0 12.1 0.0 0.0 98
3.1 1.7 9.2 7.5 2.0 0.3 186
4.0 4.0 1.0 26.3 7.1 0.0 77
6311
2442
336
476
294
99
132
a
A more detailed analysis of food usages appears in Table 8. Including stems, sprouts, and meristems. c Including bulbs and rhizomes. d Including gums, latex, sugars, and masticatories. b
An analysis of the data compiled by Duke (1972) for Central America indicates that 85% of the plant species are used for a single purpose, 10% have two uses, 4% have three uses, and 1% have four uses (leaves, flowers, fruits, and seeds). A similar analysis of the 350 edible species of native British flora yields slightly different proportions: 78%, 19%, o3%, and o1% for one, two, three, and four purposes, respectively. One of the exceptional cases of variability of uses is that of hops (Humulus lupulus). Its leaves, roots, flowers, and bark may be used as food and as condiment. The pumpkin (Cucurbita moschata) provides fruits, seeds, flowers, young leaves, and shoots for human consumption. It is clear from Table 6 that some kinds of food are scarcely used, such as bark, flowers, sap, and liquorice. In contrast, leaves (including stems, sprouts, seedlings, and shoots) and fruits seem to be the most preferred food.
Geographic Patterns of Food Plants On the basis of a sample of 1790 species from Kunkel’s list of food plants, it appears that edible herbs are more numerous
than trees, shrubs, and vines. Vines include all the climbing, creeping, and epiphytic plants. Table 7 shows that in decreasing order of species richness, the Indomalayan regions appear first, followed by the Neotropical, Palearctic, Ethiopian, Nearctic, and Australian (or Australasian) regions. By means of a chi-square test, at a significance level Po.05, the Nearctic and Australian regions show greater, and the Palearctic lower, proportions of food trees than expected. The proportion of edible shrubs does not vary significantly among regions, although at a Po.1 the Neotropics seem to have a higher proportion than the rest of the world. The Palearctic region shows a higher and the Neotropics a lower proportion of herbs, whereas the latter region is richer in vines (Po.05). In contrast, the Northern Hemisphere (Palearctic and Nearctic regions) shows a significantly lower proportion of vines than the Southern Hemisphere. According to biogeographic regions (Table 8), the Palearctic shows a significantly greater proportion of species that provide edible leaves, stems, and sprouts than the other regions. The Australian region is characterized by a greater
Edible Plants
Table 7
131
The distribution of food plants by growth form in different geographic regionsa
Growth form
Total number of spp.
Percentages (from totals)
Nearctic (North America)
Neotropical (C. & South America)
Indomalayan
Australian
Ethiopian (Africa S. of the Sahara)
Palearctic (Eurasia and North Africa)
Trees Shrubs Herbs Vines Totals
504 452 787 203 1946
25.9 23.2 40.4 10.4 B100.0
14.3 31.1 51.2 3.4 12.2
24.9 31.6 23.7 19.8 22.3
33.9 20.0 33.9 12.1 25.4
45.1 17.7 32.4 4.9 5.2
35.4 16.5 38.8 9.3 16.6
9.6 20.0 66.5 3.9 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.
Table 8 totals)
A sample of 1790 species used in 2442 ways, classified by types of food in different regions (figures are percentages of regional
Leavesa Fruits Seeds Condiments, flavorings Tea, herbals Beverages Flowers, capers Rootsb Sapsc Barks Number of items
Nearctic
Neotropical
Indomalayan
Australian
Ethiopian
Palearctic
24.3 28.3 12.8 3.0 4.9 1.0 3.3 15.8 4.6 2.0 304
14.3 52.5 11.7 3.9 2.3 2.8 2.7 7.6 2.0 0.4 487
30.0 31.9 13.7 8.2 2.2 0.3 4.8 5.8 2.0 1.1 643
25.0 14.1 28.9 2.3 4.7 0.0 1.6 8.6 13.3 1.6 128
27.3 27.3 13.3 6.4 2.2 0.2 5.4 9.1 8.1 0.7 407
48.0 14.4 10.0 8.7 3.6 0.0 4.2 9.1 1.7 0.2 471
a
Including stems, sprouts or shoots, and meristems. Including bulbs and rhizomes. c Including gums, latex, sugars, and masticatories. b
proportion of edible seeds, and the Neotropics by its abundance of fruit species. Of course, these differences were derived from the sample analyzed by us. For instance, the appearance of zero values for beverages from the Australian and Palearctic regions does not mean that there are no species of this kind in their floras; they were simply not registered in our sample of 1790 species. On the contrary, the high proportion of edible fruits in the Neotropical region is repeatedly verified in ethnobotanical studies performed in different countries of Central and South America. These contrasts may be attributed to differential characteristics of seed dispersal evolution within their plant communities, as well as to prevailing cultural trends in the use of natural resources. The possibility of ethnobotanists showing biased attention toward particular kinds of food should not be discarded.
Are Edible Weeds Weeds? The habit of gathering wild food plants has not been totally lost. Spencer maintained that ‘‘any plant is a weed if it insists upon growing where the husbandman wants another plant to grow. It is a plant out of place in the eye of man; in the nice eye of nature it is very much in place.’’ Many of our dearest crops, however, have originated from weeds. In the course of
time, humans learned how to profit from them. Oats (Avena sativa), foxtail millet (Setaria italica derived from S. viridis), chicory (Cichorium intybus), pak choi (Brassica rapa), spinach beet (Beta vulgaris), and many more species appeared originally as invaders in ancient cultivated fields. Furthermore, several cosmopolitan weeds, such as dandelion (Taraxacum officinale), garden rocket (Eruca vesicaria), common purslane (Portulaca oleracea), and shepherd’s purse (Capsella bursapastoris), are nowadays cultivated for the specialty food market. After analyzing a set of 22,521 species of plants inhabiting natural ecosystems of North and South America, we concluded that 11.3% were edible. In another sample of 1264 species from seminatural communities 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 to 35.6%. This demonstrates that the degree of environmental disturbance correlates with the proportion of weeds, which in turn increases the proportion of edible food resources. This should not be surprising given that 17 of the world’s 18 most aggressive weeds provide parts for human consumption. Because weeds are so numerous (more than 10,000 species cataloged) and so abundant (averaging 1.3 and 2.1 ton ha1 in a temperate and a tropical area of northwestern Patagonia and eastern Mexico, respectively; Dı´azBetancourt et al., 1999; Rapoport et al., 1998), they stand
132
Edible Plants
ambiguously as both enemies and potential benefactors of humanity. The prospects for the future of food plant diversity appear to be auspicious. Further research should be conducted to manage and profit from these varied and abundant natural resources. At present, more than 15,000 species of food plants are recorded and this figure is constantly growing. Yet most of the world is fed with about 20 crops. As has been pointed out by Facciola (1990), 8000 cultivars of apples have been developed by humans, but only a handful are available in supermarkets.
See also: Agriculture, Traditional. Domestication of Crop Plants. Plant Biodiversity, Overview
References Brucher H (1989) Useful Plants of Neotropical Origin and Their Wild Relatives. New York: Springer-Verlag. Campbell A (1986) The use of wild food plants, and drought in Botswana. Journal of Arid Environment 11: 81–91. Dı´az-Betancourt M, Ghermandi L, Ladio A, Lo´pez-Moreno IR, Raffaele E, and Rapoport EH (1999) Weeds as a source for human consumption. A comparison between tropical and temperate Latin America. Revista de Biologia Tropical 47: 329–338.
Duke JA (1972) Isthmian Ethnobotanical Dictionary. Maryland: Fulton. Duke JA (1992) Handbook of Edible Weeds. Boca Raton, FL: CRC Press. Facciola S (1990) Cornucopia. A Sourcebook of Edible Plants. Vista, CA: Kampong Publications. (A second, revised edition was published in 1998.) Gardarsson A and Moss R (1970) Selection of food by Icelandic Ptarmingan in relation to its availability and nutritive value. In: Watson A (ed.) Animal Population in Relation to Their Food Resources, pp. 47–71. Oxford: Blackwell. Godwin H (1960) The history of weed in Britain. In: Harper JL (ed.) The Biology of Weeds, pp. 1–10. Oxford: Blackwell. Heal OW and Felton MJ (1970) Soil amoeba: Their food and their reaction to microflora exudates. In: Watson A (ed.) Animal Population in Relation to Their Food Resources, pp. 145–162. Oxford: Blackwell. Ito S (1969) Economical plants and their distribution in Cambodia. Journal of Agricultural Science Tokyo University of Agriculture 13: 163–218. King LW (1966) Weeds of the World. Biology and Control. London: Leonard Hill. Klein DK (1970) Food selection by North American deer and their response to overutilization of preferred plant species. In: Watson A (ed.) Animal Population in Relation to Their Food Resources, pp. 25–46. Oxford: Blackwell. Kunkel G (1984) Plants for Human Consumption. Koenigsten, Germany: Koeltz Scientific Books. Martin WK (1976) The Concise British Flora in Colour. London: Ebury Press and Michael Joseph. Moerman DE (1998) Native American Ethnobotany. Portland, Oregon: Timber Press. National Research Council (1989) Lost Crops of the Incas. Washington, DC: National Academy Press. Nicholson BE, Harrison SG, Masefield GB, and Wallis M (1969) The Oxford Book of Food Plants. London: Oxford University Press. (A second, updated edition appeared as Vaughan JG and Geissler CA. (1997) The New Oxford Book of Food Plants: A Guide to the Fruit, Vegetables, Herbs, and Spices of the World.) Plotkin MJ (1993) Tales of a Shaman’s Apprentice. New York: Penguin Books. Rapoport EH, Ladio A, Raffaele E, Ghermandi L, and Sanz EH (1998) Malezas comestibles. Ciencia Hoy 9(49): 30–43.