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Duosperma crenatum (Lindau) P.G.Mey.

Hygrophila crenata Lindau (1894), Disperma parviflorum (Lindau) C.B.Clarke (1899), Disperma crenatum (Lindau) Milne-Redh. (1933).
Origin and geographic distribution
Duosperma crenatum is found in Kenya, Tanzania, Malawi, Zambia, Namibia, Zimbabwe and Mozambique.
Young leaves of Duosperma crenatum are collected from the wild, chopped and cooked alone or mixed with other vegetables such as peas or amaranth leaves, and served with a staple food. Coconut milk or pounded groundnuts are often added. A leaf infusion is drunk by women for an easy delivery. Duosperma crenatum is also used as forage.
Mature leaves of Duosperma crenatum which start to turn yellow are believed to be toxic to humans.
Erect small shrub or perennial herb up to 1.2 m tall, with more or less quadrangular, pubescent stems arising from a woody rhizome. Leaves opposite, simple, almost sessile; blade elliptical, up to 8 cm × 4 cm, narrowed at both ends, margin entire in lower part, crenate to toothed in upper part, sparsely hairy. Inflorescence an axillary, dense, cymose fascicle, with small pale green bracts. Flowers bisexual, zygomorphic, 5-merous; calyx tubular, 6–9 mm long, lobes more or less connate; corolla tubular, 9–11 mm long, 2-lipped, white with purplish dots or lines in the throat; stamens 4; ovary superior, 2-celled, style with 2 unequal stigmoid branches. Fruit a flattened, ellipsoid capsule c. 8 mm long, shiny brown, 2-seeded. Seeds discoid, with hygroscopic hairs on the margin.
Duosperma comprises about 15 species and is confined to tropical Africa, but it is not well known. Most characteristic are its flattened-ellipsoid fruits with 2 seeds only.
Duosperma crenatum occurs in dry rocky bushland, at 300–1000 m altitude.
Genetic resources and breeding
Duosperma crenatum is rather widespread and does not seem to be in danger of genetic erosion, although in some countries it is reported to be rare (e.g. in Kenya).
Duosperma crenatum will remain a minor leaf vegetable in the dry areas of East and southern Africa. Its nutritional and chemical composition require investigation.
Major references
• Burkill, I.H. & Clarke, C.B., 1899–1900. Acanthaceae. In: Thiselton-Dyer, W.T. (Editor). Flora of tropical Africa. Volume 5. Lovell Reeve & Co, London, United Kingdom. pp. 1–262.
• Ruffo, C.K., Birnie, A. & Tengnäs, B., 2002. Edible wild plants of Tanzania. Technical Handbook No 27. Regional Land Management Unit/ SIDA, Nairobi, Kenya. 766 pp.
Other references
• Agnew, A.D.Q. & Agnew, S., 1994. Upland Kenya wild flowers: a flora of the ferns and herbaceous flowering plants of upland Kenya. 2nd Edition. East Africa Natural History Society, Nairobi, Kenya. 374 pp.
• Brummitt, R.K., 1974. New combinations and three new Zambian species in Duosperma (Acanthaceae). Kew Bulletin 29: 411–414.
P.C.M. Jansen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

G.J.H. Grubben
Prins Hendriklaan 24, 1401 AT Bussum, Netherlands
O.A. Denton
National Horticultural Research Institute, P.M.B. 5432, Idi-Ishin, Ibadan, Nigeria
Associate Editors
C.-M. Messiaen
Bat. B 3, Résidence La Guirlande, 75, rue de Fontcarrade, 34070 Montpellier, France
R.R. Schippers
De Boeier 7, 3742 GD Baarn, 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

Correct citation of this article:
Jansen, P.C.M., 2004. Duosperma crenatum (Lindau) P.G.Mey. In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.