AgroForestryTree Database
Senna didymobotrya
 Species identityEcology and distributionPropagation and managementFunctional usesPests and diseasesAdditional InfoBibliographyImages |
Species identity
TaxonomySynonym(s)
Common names
(Danish) : African wild sensitive
(Filipino) : wild senna
Botanic description
Usually a several-stemmed shrub or small tree, 0.5-5(-9) m tall. Branches terete, striate, pubescent to villous, rarely subglabrous. Leaves simply paripinnate, narrowly oblong-elliptical in outline, 10-50 cm long; stipules broadly ovate-cordate, 6-17 mm x 8-10 mm, acuminate, palmately veined, reflexed, tardily caducous; petiole terete, 1-8 cm long, rachis up to 40 cm long, both pubescent and eglandular; petiolules up to 3 mm long; leaflets in 8-18 pairs, chartaceous, elliptical-oblong, 2-6.5 cm x 0.5-2.5 cm, 2-3 times longer than wide, base oblique, apex rounded but mucronate, pubescent to glabrescent, marginal vein distinct. Inflorescence an erect, axillary, 20-30 flowered, spike-like raceme, 10-50 cm long; peduncle terete, 5-8 cm long, pubescent; bracts broadly ovate, 8-27 mm x 5-15 mm, black green, at first imbricate and enclosing the flower buds; bracteoles absent; pedicel slender, 3-10 mm long, densely pubescent; sepals 5, subequal, oblong-obovate, 9-14 mm long, puberulous, green; petals 5, slightly unequal, at first incurved, later on more spreading, ovate to obovate, 17-27 mm x 10-16 mm, with a slender, about 1 mm long claw, glabrous, bright yellow, delicately veined; stamens 10, filaments shorter than anthers, anthers of 2 lower stamens 9-11 mm long, 3 upper stamens staminodial, anthers of 5 median stamens about 5 mm long; ovary and stipe velvety pubescent; style slender, glabrous, recurved, about 1 cm long; stigma punctiform. Fruit a flat, 9-16 seeded pod, linear-oblong, 7-12 cm x 1.5-2.5 cm, glabrescent, short beaked, dehiscent or indehiscent when dry, depressed between the seeds, sutures raised, blackish-brown. Seed flattened, oblongoid, apiculate, 8-9 mm x 4-5 mm x 2.5 mm, smooth, pale brown; areole elliptical, 3-4 mm x 0.7-1.5 mm. In the older literature, this species is best known as Cassia didymobotrya. Until the beginning of the 1980s, Cassia L. was considered to be a genus with over 500 species.
Ecology and distribution
History of cultivationIt was introduced into Tropical Asia and America as a green manure and cover crop, and later as ornamental. It sporadically naturalized in frostless regions, including Malesia. It is now grown throughout the world as an ornamental.
Natural Habitat
In its natural habitat S. didymobotrya is often ruderal in riparian montane wooded grassland or evergreen bushland. It tolerates ligh frost.
Native of tropical East and Central Africa, from Ethiopia and Sudan to Angola and Mozambique. It was introduced into Tropical Asia and America as a green manure and cover crop, and later as ornamental. It sporadically naturalized in frostless regions, including Malesia. It is now grown throughout the world as an ornamental.
Biophysical limitsAltitude: 900-2400 m.
Reproductive Biology
S. didymobotrya flowers profusely twice a year; in temperate regions it flowers throughout the summer.
Propagation and management
Propagation methodsS. didymobotrya is easly propagated by seed; cuttings are said not to be successful. The seed may be sown in the nursery or directly in the field.Tree Management
Plantation: When seedling planted as a small shade tree in tea it is spaced at about 5 m x 5 m. Husbandry: The plants can be lopped several times per year to provide green manure. Lopping is preferably done when the plants are in flower, when the nutrient content in the leaves is high. The plant yields a fairly large amount of lopping. About 5 t of green material provides 35.5 kg nitrogen. In temperates areas, potted ornamental plants are overwintered in greenhouses.
Functional uses
ProductsMedicine: It is widely used as a purgative and an anti-malaria medicine. A decoction of the leaves is used against stomach complaints. Poison: In Africa, it is commonly used as a stupefacient poison for fishing.Services
Ornamental: It is now popular as an ornamental plant owing to its bright yellow flowers and black-green bracts. It is used as ornamental plant in Africa. Shade or shelter: It has been used as a shade tree in tea plantations. Soil improver: It was introduced as a green manure in India, Sri Lanka, Peninsular Malaysia and Java. It was introduced as a cover crop in India, Sri Lanka, Peninsular Malaysia and Java. Other services: In sites where Erythrina spp. do not grow well, S. didymobotrya may be a valuable substitute.
Pests and diseasesIt is hardy and quite free from diseases and pests.
Additional Information
DevelopmentJuvenile stems tend to be somewhat tender and should be staked. When growth is very rapid, plants are apt to become straggly. S. didymobotrya withstands lopping well. The bracts, stipules and indumentum of S. didymobotrya are quite variable. In the axil of the leaves an abortive inflorescence is often present.Properties
Other products: The aboveground biomass of S. didymobotrya grown as ground cover in Sri Lanka was found to contain 0.7 g N per 100 g fresh material. When in flower or bruised, the plant emits an unpleasant smell said to be very reminiscent of mice. Poison: In vitro cultures of S. didymobotrya produced chemical compounds that can be converted into low-energy sweeteners and insecticides. Medicine: Leaves and roots contain a number of anthraquinones, choline, and the trisaccharide raffinose.
Prospects
S. didymobotrya used to be a ground cover and green manure crop, appreciated mainly as an alternative plant in locations where Erythrina spp. did not florish. It has now been largely replaced as a green manure crop by species such as Tephrosia candida (Roxb.) DC., T. purpurea (L.) Pers. and T. vogelii Hooker f. Its potential as an ornamental pot plant is being developed.