Tylosema esculentum
| Tylosema esculentum | |
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| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Rosids |
| Order: | Fabales |
| Family: | Fabaceae |
| Subfamily: | Cercidoideae |
| Tribe: | Bauhinieae |
| Genus: | Tylosema |
| Species: | T. esculentum |
| Binomial name | |
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Tylosema esculentum (Burch.) A.Schreib. |
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| The range of Tylosema esculentum. | |
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Tylosema esculentum, with common names gemsbok bean and marama bean, is a long-lived perennial legume native to arid areas of southern Africa. Stems grow at least 3 metres, in a prostrate or trailing form, with forked tendrils that facilitate climbing. A raceme up to 25 millimetres (1 in) long, containing many yellow-orange flowers, ultimately produces an ovate to circular pod, with large brownish-black seeds.
Summer growth is typically prodigious, particularly in plants older than one year - due in part to its large underground tuber. The plant is dormant over winter in its native home - South Africa, Namibia and Botswana - but might possibly remain evergreen in less harsh environments.
The marama bean is adapted to its native region of Southern Africa and therefore grows in dry and low-moisture soils. Its drought tolerance is accordingly high. The fact that the marama bean is adapted to harsh environments offers potential to extend the agricultural activity into regions which are dry or unproductive at the moment. Nevertheless, it needs to be investigated whether it can grow on different soil types.
The nutritional value of the marama bean is astonishingly high for an unimproved legume. The tubers have a high protein content of 9.0% and also have a high amino acid content. The tubers of cassava, for example, only have a protein content of 1-3%, while yam has one of 7%. Also the grain is relatively high in protein with a share of 30-39%. The concentration of sulphur-containing amino acids is high as well (with a lysine content of 5.0% and a methionine content of 0.7%). This shows that the protein content of the seeds is comparable to the one of commercial soybeans, which have a content of 38-40%. Therefore, the potential of the marama bean is high to replace the soybean as a protein source, once there have been genetical improvements.
The tuber can grow very large - at least 10 kg, perhaps much larger. In Botswana a tuber of 277 kg has been found.
The seeds develop in typical legume pods, albeit large and squat in shape - with typically one or two seeds per pod.
The plant is a significant food-source for the people of the Kalahari because of the high protein and oil content of its large seeds (20-30gm each). The seeds are usually roasted, imbuing them with a more palatable flavour - comparable to cashew or chestnut. The seeds can also be ground or boiled. The beans keep well, due to their hard outer shell.
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Wikipedia