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Cynanchum schistoglossum Schltr.

Protologue
Journ. Bot. 33: 271 (1895).
Family
Asclepiadaceae (APG: Apocynaceae)
Synonyms
Cynanchum brevidens N.E.Br. (1895), Cynanchum vagum N.E.Br. (1895), Cynanchum dewevrei De Wild. & T.Durand (1900).
Origin and geographic distribution
Cynanchum schistoglossum is distributed in southern Africa from Kenya, Burundi and DR Congo south to Angola and South Africa.
Uses
In Malawi the leaves of Cynanchum schistoglossum are eaten raw or cooked as a side-dish vegetable, usually with salt added. The product is well liked and commonly used in the rainy season.
Properties
No information is available on the phytochemistry of Cynanchum schistoglossum. Cynanchotoxin or vincetoxin are sometimes present in the leaves and roots of other Cynanchum species (e.g. in Cynanchum africanum (L.) Hoffsgg. and Cynanchum ellipticum (Harvey) R.A.Dyer), causing cynanchosis (’krampsiekte’) in livestock in South Africa.
Botany
Perennial herb up to 3 m tall, with woody rhizome; stem twining, strongly branched, containing latex. Leaves opposite, simple; petiole 1–2.5 cm long; blade ovate-lanceolate, 3.5–6 cm × 1.5–3.5 cm, base usually cordate, apex acute to acuminate, margin entire, sparsely covered with erect trichomes. Inflorescence a helicoid cyme, 5–20-flowered. Flowers bisexual, regular, 5-merous, musky scented; pedicel 3–8 mm long; calyx with triangular lobes, c. 1 mm × 0.5 mm; corolla cup-shaped, 1–3.5 mm long, white to yellow-green, lobes lanceolate, incurved; corona cup-shaped, c. 1.5 mm long, white, dentate at apex; stamens with very short free filaments, anthers winged and with connective appendage; ovary superior, stylar head depressed conical. Fruit consisting of a pair of fusiform, brown, glabrous follicles, each one 5–5.5 cm × 5–6 mm. Seeds ovoid, c. 5 mm × 4 mm, pale brown, at apex bearing a coma of hairs 2–2.5 cm long.
The genus Cynanchum comprises about 250 species worldwide. The major centre of diversity in Africa is Madagascar with approximately 70 species, minor centres of diversity are eastern Africa, the Horn of Africa and southern Africa with 10–15 species each. Cynanchum schistoglossum is the most variable Cynanchum species on the African mainland. Corona dentation and degree of fusion differ considerably among populations. The very small flowers are characteristic for the species.
Ecology
Cynanchum schistoglossum grows in forest margins, thickets and grasslands, often near water, but also along roadsides and in disturbed localities, from sea-level up to 1800 m altitude. It is found flowering year-round with a peak between April and October.
Genetic resources and breeding
In southern Africa Cynanchum schistoglossum occurs locally, but is not rare or endangered.
Prospects
The nutritive value of Cynanchum schistoglossum leaves and possibilities for its cultivation need more investigation.
Major references
• Liede, S., 1993. A taxonomic revision of the genus Cynanchum L. (Asclepiadaceae) in southern Africa. Botanische Jahrbücher 114: 503–550.
• Liede, S., 1996. A revision of Cynanchum (Asclepiadaceae) in Africa. Annals of the Missouri Botanical Garden 83: 283–345.
• Williamson, J., 1955. Useful plants of Nyasaland. The Government Printer, Zomba, Nyasaland. 168 pp. (Reprint: Williamson, J., 1975. Useful plants of Malawi. University of Malawi, Zomba, Malawi).
Other references
• Watt, J.M. & Breyer-Brandwijk, M.G., 1962. The medicinal and poisonous plants of southern and eastern Africa. 2nd Edition. E. and S. Livingstone, London, United Kingdom. 1457 pp.
Author(s)
P.C.M. Jansen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
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. Cynanchum schistoglossum Schltr. In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.