Yeheb (Cordeauxia edulis Hemsl.) is a woody legume of the arid semi-deserts of Ethiopia and Somalia. It is a multipurpose shrub highly valued both for its nutritious nut, which is a staple food in the drier areas of the region, and as forage for livestock during the dry season. Yeheb plays an important role in the livelihoods of the local communities but it is currently considered as a vulnerable species (Yusuf et al., 2013). Yeheb is the only species of the genus Cordeauxia (Brink, 2006).
Yeheb is a perennial, leguminous, evergreen, much-branched shrub (tree), 1.6 to 4 m tall (Orwa et al., 2009; NRC, 1979). It develops deep roots that tap soil moisture down to a depth of 3 m, and lateral roots that explore the soil layers between 10-40 cm, and down to 2.5 m. The stems are variable in diameter and are all bearing red dots (red glands). The leaves are alternate and paripinnate with 2-12 elliptic to oblong leaflets, 3-5 cm long x 1.5-2.5 cm wide. The leaflets are olive green in colour and bear conspicuous red glands on their lower surface. The limbs are covered with an extremely thick cuticle that protects the leaves from drought. The inflorescence is a terminal raceme bearing yellow, pentamerous, hermaphrodite flowers, 2.5 cm in diameter (Orwa et al., 2009; Brink, 2006). The fruit is an ovoid, slightly curved, dehiscent pod, 4-6 cm long x 2 cm wide. The pods contain 1-2 ovoid seeds, 2-4.5 cm long, with a thin easily cracked testa (Brink, 2006). It has been suggested that 2 varieties of yeheb (sulei and mogollo) exist in Somalia, distinguished by their stem, fruit and leaf sizes (Orwa et al., 2009). Mogollo seeds are claimed to be sweeter than those of sulei (Brink, 2006).
Yeheb is used as a source of staple food for nomad populations and as fodder for livestock (Yusuf et al., 2013). It is considered a famine food in Ethiopia (Guinand et al., 2001). The seeds ("nuts") are edible, much relished, and often compared to cashew nuts, almonds or chestnuts. They provide a balanced diet containing high energy (high fat and starch contents), and valuable protein with good amino acid content similar to that of legume crops, though deficient in methionine. They are eaten fresh, dried, roasted, boiled, made into a soup, or used as a coffee substitute (Yusuf et al., 2013; Brink, 2006). Yeheb nuts provide an oil used to make soap (Orwa et al., 2009; Brink, 2006; Guinand et al., 2001). The seeds are reported to have ethnomedicinal properties (Yusuf et al., 2013; Brink, 2006). The nectar of yeheb is favoured by bees, and the shrubs are used as living fences and for soil conservation (Yusuf et al., 2013; Vivero et al., 2005). Yeheb provides good firewood and timber, which is used in 90% of house constructions in areas where yeheb trees are still numerous (Yusuf et al., 2013; Orwa et al., 2009). Yeheb leaves and seeds contain the red dye cordeauxiaquinone (Söderberg, 2010). Leaf extracts form fast and insoluble dyes with metals and have been used as mordants in dyeing fabrics (NRC, 1979). Yeheb nuts are sold locally and in markets as a source of income for harvesters (Yusuf et al., 2013).
Yeheb is an outstanding source of fodder for many livestock species (camels, sheep, goats and cattle) during the dry season, and is sometimes the only available and palatable source of green forage during this period (Orwa et al., 2009; Brink, 2006). Local herders believe that yeheb prevents diseases in livestock (Yusuf et al., 2013).