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Cordeauxia edulis Hemsl.

Protologue
Bull. Misc. Inform. Kew: 361 (1907).
Family
Caesalpiniaceae (Leguminosae - Caesalpinioideae)
Chromosome number
2n = 24
Vernacular names
Yeheb nut, yeheb bush (En). Yeheb (Fr).
Origin and geographic distribution
Cordeauxia edulis is endemic to south-eastern Ethiopia (eastern Ogaden) and central Somalia. It is cultivated on a small scale in Somalia and near Voi in Kenya, where it was introduced in the 1950s. It has been introduced on an experimental scale into Sudan, Tanzania, Yemen, Israel and the United States.
Uses
In its native region the seeds (‘yeheb nuts’) of Cordeauxia edulis are an important food for pastoralists, especially as a famine food during drought periods. They are eaten fresh, dried, roasted or boiled. The seeds taste sour when eaten fresh or dried, but have a sweetish, agreeable, chestnut-like taste after roasting. The water in which the seeds have been boiled is sweet and is sometimes consumed. The seed oil is useful for soap making. The seeds have been mentioned as a coffee substitute. Cordeauxia edulis is said to regulate gastric secretion and to permit treatment of ulcers due to hot food. It is also believed to alleviate anaemia by augmenting the number of red blood cells. The leaves are made into a tea. Cordeauxia edulis is an important dry-season fodder for camels, goats, sheep and cattle, but in the rainy season other plants are preferred. The red pigment in the glands on several plant parts forms vividly coloured, fast and insoluble combinations with many metal mordants, and is locally used for dyeing textiles. The wood is used as firewood.
Production and international trade
The seeds of Cordeauxia edulis are mostly consumed locally, but are also sold in towns. Demand exceeds supply because of rapidly diminishing plant populations. From Ethiopia the seeds are exported to Somalia and Arab countries, but no quantitative information is available. Cordeauxia edulis seeds have export potential for European markets as ‘dessert nuts’.
Properties
Shelled Cordeauxia edulis seeds contain per 100 g edible portion: water 11.1 g, energy 1666 kJ (398 kcal), protein 10.8 g, fat 12.0 g, carbohydrate 63.9 g, fibre 1.4 g, Ca 32 mg, P 185 mg and Fe 6.4 mg (Leung, Busson & Jardin, 1968). The protein content is considerably less than that of most pulses, but the fat content is higher. In various studies the protein was found to resemble that of other pulses in containing considerable and well-balanced amounts of essential amino acids, especially lysine (3.9–6.9%), and being deficient in methionine. The seed lipids contain palmitic acid (26–31%), stearic acid (12–13%), oleic acid (31–32%), linoleic acid (25–30%) and linolenic acid (traces). The seed oil is yellow. The seeds contain trypsin inhibitors, which can be inactivated by boiling. Cordeauxia edulis leaves from Somalia have a low crude protein content (7.5–11.8%), energy content (559–586 kJ per 100 g dry matter) and in vitro dry matter digestibility (27.2–39.8%). Furthermore they have a high tannin content (2.5–2.7%), which reduces their feed quality. The leaves contain N 1.2–1.5%, P 0.1%, Ca 0.7–1.8%, Mg 0. 1–0.2% and S 0.1–0.2%. According to herdsmen the meat of animals fed with Cordeauxia edulis is particularly tasty. Cordeauxia edulis is reputed to cause intestinal disorders in goats when eaten as the sole diet.
The red pigment of Cordeauxia edulis is cordeauxione (cordeauxiaquinone), a naphthaquinone which is unknown in other plants. The leaves contain 0.7–0.8% of this dye. When fresh leaves are handled, they stain the hands red. When animals eat the leaves, their teeth are stained orange-red and the dye is also deposited as a calcium complex in their bones, which become pink. This colouration is considered a sign of good meat quality, e.g. in Somalia and Saudi Arabia. The wood of Cordeauxia edulis has been described as good firewood, inflammable even when wet.
Description
Densely branched, evergreen shrub or small tree up to 2.5(–4) m tall, with a long taproot up to 3 m deep and lateral roots at 10–40 cm below the soil surface extending up to 2.5 m; stem with conspicuous red glands. Leaves alternate, paripinnate, without stipules; leaflets (2–)4–8(–12), elliptical-oblong, up to 3(–5) cm × 1.5(–2.5) cm, leathery, olive-green above, paler with many red glands beneath. Inflorescence a terminal few-flowered raceme. Flowers bisexual, almost regular, 5-merous, c. 2.5 cm in diameter; sepals oblong, c. 1 cm long, obtuse, green with red glands; petals almost equal, c. 1.5 cm long, yellow, clawed; stamens 10, free, straight, filaments hairy below the middle; ovary superior, 1-celled, shortly stalked, densely glandular; stigma obtuse. Fruit an ovoid pod, 4–6 cm × 2 cm, shortly stalked, with a curved beak, opening by 2 hard valves, 1(–6)-seeded. Seed ovoid, 2.0–4.5 cm long, with thin, easily cracked testa. Seedling with epigeal germination; cotyledons thick.
Other botanical information
Cordeauxia comprises a single species. It is closely related to Caesalpinia and Stuhlmannia. Cordeauxia edulis is rather variable, and sometimes two types are distinguished: ‘suley’ (‘sulei’) and ‘moqley’ (‘mogollo’). ‘Suley’ is pale green, with a large stem diameter and large leaflets. ‘Moqley’ is dark green, with small stem diameter and small leaflets. Pods of the ‘moqley’ type contain a large single seed. Pods of the ‘suley’ type contain several seeds, which are compressed laterally and smaller in size. The seeds of the ‘moqley’ type are claimed to be sweeter. Mixed stands of the two types exist but are rare.
The leaves of Cordeauxia edulis have an extremely thick cuticle and mesophyll consisting of palisade cells with lateral walls capable of folding in a concertina-like way. This may enable the leaves to survive extended periods of drought and store water quickly when available, thus allowing them to remain evergreen.
Growth and development
Germination of Cordeauxia edulis is rapid. Subsequent growth of the aerial parts is very slow, especially in the seedling stage, whereas the root system grows rapidly. Plants 60 cm tall may already have roots 2 m long. Under natural conditions flowering starts just before the onset of the rains, when the relative humidity rises, or immediately after the first rains, whereas some sources indicate flowering is year-round but more profuse during the rainy season. The floral parts fall soon after pollination, leaving only the fertilized ovary. The fruit ripens 10–15 days after flowering. Unlike in many other plants, seeds of Cordeauxia edulis mature when the plant moisture content is at its peak. Fruit development stops when the rain ceases and the ovaries remain dormant for 4–5 months, resuming ripening after the rains have returned. Cordeauxia edulis requires 3–4 years to bear fruit. The plants are long-lived, some reaching more than 200 years according to Somali sources, and they coppice well. It is unclear whether Cordeauxia edulis is able to fix atmospheric nitrogen.
Ecology
In Ethiopia and Somalia Cordeauxia edulis is found in semi-desert regions in Acacia - Commiphora deciduous bushland and shrub vegetation at (100–) 200–500(–1000) m altitude, with a minimum distance of 100 km to the Indian Ocean. These regions have an average annual temperature of 26–30°C, an average annual rainfall of 100–300(–400) mm and two rainy seasons.
Cordeauxia edulis is resistant to normal drought periods of 4–5 months and occasional drought of up to 15 months. It does not tolerate frost. It grows on deep, permeable, reddish, sandy, slightly alkaline (pH up to 8–8.5), non-calcareous soils with a very low nutrient status. Cordeauxia edulis does not tolerate waterlogging.
Propagation and planting
Cordeauxia edulis is normally propagated by seed, but vegetative propagation through stem cuttings is also possible. The 100-seed weight is 100–300 g. The seed is often said to be viable for a few months only, but seed coated in wood ash and stored in a sack is reputed to remain viable for at least a year. Direct sowing in the field seems preferable, as the fast-growing taproot is easily damaged in transplanting, with mortality rates of up to 100%. No information is available on optimum plant densities and spacings. Under natural conditions in Somalia there are up to 320 plants/ha, depending on growing conditions and distance from villages and water points.
Management
Cordeauxia edulis is usually collected from the wild. Ample water is needed for seedling establishment, but once the plants are established, little care is needed.
Diseases and pests
Cordeauxia edulis shrubs are essentially free of insect pests, but storage pests, such as weevils and larvae of moths, heavily attack the seeds.
Harvesting
Cordeauxia edulis fruits are picked from the plant, the fruit wall is peeled off and the seeds are placed in sacks. The seeds are often harvested before maturity, which may be a factor in the low seed viability often encountered. Usually all seeds are removed from the plant at the same time, hampering regeneration of natural stands. Fruits can be harvested twice a year, provided rainfall is adequate during both rainy seasons.
Yield
The seed yield of Cordeauxia edulis is 5–8 kg per plant per year, but may be zero in drought years. The estimated average forage production is 325–450 kg/ha (1.4–2 kg/plant).
Handling after harvest
To prevent Cordeauxia edulis seeds from being attacked by insects, freshly picked seeds are roasted or boiled to kill insects and harden the seed coat. In this form they fetch a higher price on the market, but the practice contributes to the difficulty of obtaining viable seed for planting. Pastoralists keep the seeds for many years in containers made of tanned, dried camel leather. For dyeing, Somalis pulverize about 200 g of dried leaves in water to dye about 10 m2 cotton cloth. Alkaline extracts develop a more intense violet colour than neutral or slightly acid extracts.
Genetic resources
The populations of Cordeauxia edulis declined in the 20th century due to deterioration of the vegetation caused by overgrazing, and overharvesting of the seed. In the IUCN Red List of Threatened Plants (1997) Cordeauxia edulis is classified in the category ‘rare’, which includes taxa with small world populations that are not at present considered endangered or vulnerable, but are at risk. Regeneration and protection of natural stands and cultivation in afforestation projects, in and outside its native region, are recommended. Germplasm collections are seriously lacking, with one accession kept in Ethiopia at the International Livestock Research Institute (ILRI), Addis Ababa, one in Kenya at the National Genebank of Kenya, Kikuyu and one in the United States at the Southern Regional Plant Introduction Station, Griffin, Georgia.
Prospects
Cordeauxia edulis is a useful multipurpose plant in dry areas of Ethiopia and Somalia. Natural stands are threatened by over-exploitation, and protection of natural stands as well as expansion of its cultivation are called for. Cordeauxia edulis could be a promising potential source of food and dry-season fodder for other hot, arid regions. However, the limited availability of viable seed and the shortage of knowledge on the crop, especially its propagation, agronomic practices and potential for selection and breeding, are important constraints.
Major references
• Assefa, F., Bollini, R. & Kleiner, D., 1997. Agricultural potential of little used tropical legumes with special emphasis on Cordeauxia edulis (ye-eb nut) and Sphenostylis stenocarpa (African yam bean). Giessener Beiträge zur Entwicklungsforschung 24: 237–242.
• Bally, P.R.O., 1966. Miscellaneous notes on the flora of Tropical East Africa No 29: Enquiry into the occurrence of the yeheb nut (Cordeauxia edulis) in the Horn of Africa. Candollea 21(1): 3–11.
• Booth, F.E.M. & Wickens, G.E., 1988. Non-timber uses of selected arid zone trees and shrubs in Africa. FAO Conservation Guide No 19. Food and Agriculture Organization, Rome, Italy. 176 pp.
• Drechsel, P. & Zech, W., 1988. Site conditions and nutrient status of Cordeauxia edulis (Caesalpiniaceae) in its natural habitat in Central Somalia. Economic Botany 42(2): 242–249.
• Miège, J. & Miège, M.-N., 1978. Cordeauxia edulis - a Caesalpiniaceae of arid zones of East Africa: caryologic, blastogenic and biochemical features; potential aspects for nutrition. Economic Botany 32(3): 336–345.
• National Academy of Sciences, 1979. Tropical legumes: resources for the future. National Academy of Sciences, Washington, D.C., United States. 331 pp.
• Seegeler, C.J.P., 1983. Oil plants in Ethiopia, their taxonomy and agricultural significance. Agricultural Research Reports 921. Pudoc, Wageningen, Netherlands. 368 pp.
• Thulin, M., 1989. Fabaceae (Leguminosae). In: Hedberg, I. & Edwards, S. (Editors). Flora of Ethiopia. Volume 3. Pittosporaceae to Araliaceae. The National Herbarium, Addis Ababa University, Addis Ababa, Ethiopia and Department of Systematic Botany, Uppsala University, Uppsala, Sweden. pp. 49–251.
• Thulin, M., 1993. Fabaceae (Leguminosae). In: Thulin, M. (Editor). Flora of Somalia. Volume 1. Pteridophyta; Gymnospermae; Angiospermae (Annonaceae-Fabaceae). Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 341–465.
• Yahya, A. & Durand, B., 1991. Le yeheb: un arbuste aux multiples usages en forte régression. In: Riedacker, A., Dreyer, E., Pafadnam, C., Joly, H. & Bory, G. (Editors). Physiologie des arbres et arbustes en zones arides et semi-arides. Séminaire, Paris-Nancy, 20 mars–6 avril 1990. John Libbey Eurotext, Paris, France. pp. 457–463.
Other references
• Bekele-Tesemma, A., Birnie, A. & Tengnäs, B., 1993. Useful trees and shrubs for Ethiopia: identification, propagation and management for agricultural and pastoral communities. Technical Handbook No 5. Regional Soil Conservation Unit/SIDA, Nairobi, Kenya. 474 pp.
• Brenan, J.P.M., 1967. Leguminosae, subfamily Caesalpinioideae. In: Milne-Redhead, E. & Polhill, R.M. (Editors). Flora of Tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 230 pp.
• Curtis, J.D., Lersten, N.R. & Lewis, G.P., 1996. Leaf anatomy, emphasizing unusual ‘concertina’ mesophyll cells, of two East African legumes (Caesalpinieae, Caesalpinioideae, Leguminosae). Annals of Botany 78(1): 55–59.
• Drechsel, P., 1988. Die Bedeutung heimischer Gehölze in den Somalischen Weideländern am Beispiel von Cordeauxia edulis. Giessener Beiträge zur Entwicklungsforschung, Serie 1, 17: 125–131.
• Drechsel, P. & Assefa, F., 1991. The relevance of native trees and shrubs in the Somalian rangelands, taking Cordeauxia edulis by way of example. Plant Research and Development 33: 73–79.
• El-Zeany, B.A. & Gutale, S.F., 1982. The nutritional value of yeheb-nut (Cordeauxia edulis Hemsl.). Die Nahrung 26(9): 797–802.
• Eugster, C.H., 1967. Neue Blattfarbstoffe. Palette 27: 25–30.
• Greenway, P.J., 1947. Yeheb. The East African Agricultural Journal 12: 216–219.
• Hanelt, P. & Institute of Plant Genetics and Crop Plant Research (Editors), 2001. Mansfeld’s encyclopedia of agricultural and horticultural crops (except ornamentals). 1st English edition. Springer Verlag, Berlin, Germany. 3645 pp.
• Hedberg, I., 1979. Systematic botany, plant utilization and biosphere conservation. Proceedings of a symposium held in Uppsala in commemoration of the 500th anniversary of the university. Almqvist & Wiksell International, Stockholm, Sweden. 157 pp.
• International Centre for Research in Agroforestry (ICRAF), undated. Agroforestree Database. [Internet] World Agroforestry Centre, Nairobi, Kenya. http://www.worldagroforestrycentre.org/ Sites/TreeDBS/AFT/ AFT.htm. Accessed March 2003.
• Kebebew, F., 1988. PGRC/E takes steps to conserve ye-eb nut (Cordeauxia edulis), the most hardy shrub in South-East Ethiopia. PGRC/E-ILCA Germplasm Newsletter 17: 12–13.
• Lepidi, A.A., Nuti, M.P. & Capretti, P., 1979. Poorly known nitrogen fixing symbioses. I. Cordeauxia edulis in the Horn of Africa. Agricoltura Italiana 108: 341–348.
• Leung, W.-T.W., Busson, F. & Jardin, C., 1968. Food composition table for use in Africa. FAO, Rome, Italy. 306 pp.
• Lewis, G.P., 1996. Notes on Stuhlmannia Taub. and the correct placement of Caesalpinia insolita (Harms) Brenan & J.B. Gillett (Leguminosae; Caesalpinioideae: Caesalpinieae). Kew Bulletin 51(2): 377–379.
• Miège, J., Crapon de Caprona, A. & Lacotte, D., 1978. Caractères séminaux, palynologiques, caryologiques de deux légumineuses alimentaires: Cordeauxia edulis Hemsley et Psophocarpus tetragonolobus (L.) DC. Candollea 33(2): 329–347.
• Walter, K.S. & Gillett, H.J. (Editors), 1998. 1997 IUCN red list of threatened plants. IUCN, Gland, Switzerland. 862 pp.
• Wickens, G.E., 1998. Ecophysiology of economic plants in arid and semi-arid lands. Springer Verlag, Berlin, Germany. 343 pp.
• Zemede Asfaw & Mesfin Tadesse, 2001. Prospects for sustainable use and development of wild food plants in Ethiopia. Economic Botany 55(1): 47–62.
• Zimsky, M., 1990. Using nitrogen fixing trees for human food. NFTA (Nitrogen Fixing Tree Association) News 11: 1–2, 6.
Sources of illustration
• Booth, F.E.M. & Wickens, G.E., 1988. Non-timber uses of selected arid zone trees and shrubs in Africa. FAO Conservation Guide No 19. Food and Agriculture Organization, Rome, Italy. 176 pp.
• Thulin, M., 1983. Leguminosae of Ethiopia. Opera Botanica 68: 1–223.
Author(s)
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
G. Belay
Ethiopian Agricultural Research Organization, Debre Zeit Center, P.O. Box 32, Debre Zeit, Ethiopia
Associate editors
J.M.J. de Wet
Department of Crop Sciences, Urbana-Champaign, Turner Hall, 1102 South Goodwin Avenue, Urbana, IL 61801, United States
O.T. Edje
Faculty of Agriculture, University of Swaziland, P.O. Luyengo, Luyengo, Swaziland
E. Westphal
Ritzema Bosweg 13, 6706 BB Wageningen, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Photo editor
A. de Ruijter
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article:
Brink, M., 2006. Cordeauxia edulis Hemsl. In: Brink, M. & Belay, G. (Editors). PROTA 1: Cereals and pulses/Céréales et légumes secs. [CD-Rom]. PROTA, Wageningen, Netherlands.
Distribution Map wild


1, flowering twig; 2, fruit; 3, seed; 4, seed kernel.
Redrawn and adapted by Achmad Satiri Nurhaman



camel browsing Cordeauxia edulis


leaves and flowers