Common Name: African Yam Bean

General Information

Sphenostylis stenocarpa is a perennial climbing plant producing twining stems around 1 - 3 metres long from a tuberous rootstock. The stems scramble over the ground, climbing into the surrounding vegetation for support.
The plant is harvested from the wild and also cultivated as a food. It is an important root crop in Africa, with a high potential for cultivation in other areas of the world[]. It is a staple food in many parts of tropical Africa, cultivated especially for its edible roots, but also for its leaves, seeds and seedpods[, , ].

Known Hazards

None known

Botanical References

Range

Tropical Africa - Guinea to Ethiopia and south to Angola, Zimbabwe and Mozambique

Habitat

Brachystegia woodland, riparian and lakeshore bushland, grassland, roadsides, often in rocky places and on termite mounds, at elevations of 10 - 1,500, occasionally 2,000 metres[].

Properties

Edibility Rating
Habit	Perennial Climber
Height	2.00 m
Cultivation Status	Cultivated, Wild

Cultivation Details

A plant of the tropics, where it is found at elevations up to 2,000 metres. It grows best in areas where annual daytime temperatures are within the range 23 - 29°c, but can tolerate 15 - 35°c[]. It prefers a mean annual rainfall in the range 1,000 - 1,200mm, but tolerates 800 - 1,400mm[]. Requires a dry period when flowering[].
Prefers a position in full sun[]. Grows best in a fertile, sandy soil[]. Prefers a pH in the range 5.5 - 6, tolerating 4.5 - 7[].
Although perennial, the plant is usually treated as an annual in cultivation[].
Harvesting of the seedpods can commence about 5 months after sowing, and continue for another 2 months[].
Tubers mature 7 - 8 months after sowing[].
Optimum yields of the seed is 2 tonnes per hectare, and of the tubers 4 tonnes[].
Plants are probably day length sensitive[].
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[]. When removing plant remains at the end of the growing season, it is best to only remove the aerial parts of the plant, leaving the roots in the ground to decay and release their nitrogen.

Edible Uses

Immature seedpods - cooked and used as a vegetable[]. The pods are up to 25cm long and 15mm wide[].

Seeds - cooked[]. Rich in protein, they are boiled and eaten as a vegetable, or added to soups etc[]. The seed is about 9mm long[].

Root - raw or cooked[]. The white fleshy roots can be cooked like potatoes, which they resemble in taste[]. They are rich in protein[].

Leaves - cooked and used as a vegetable[].

Medicinal

None known

Other Uses

None known

Propagation

Seed - sow in situ[].
Division of tubers[].

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Captcha: if i have 3 bananas, and i eat them all, how many bananas did i just eat?