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Oxygonum alatum Burch.

Trav. S. Africa 1: 548 (1822).
Oxygonum acetosella Welw. (1869).
Vernacular names
Salt of the tortoise (En).
Origin and geographic distribution
Oxygonum alatum occurs in southern Africa, from Angola and Zambia south to South Africa.
In the Kalahari Desert the whole young plant or the leaves are eaten raw, not only for the refreshing acid taste, but also for the moisture it contains.
Annual herb, much branched from the crown of the root with erect, finely pubescent stems up to 30 cm tall; stem, ocrea and petiole often covered with cup-like scales. Leaves alternate, simple; ocrea funnel-shaped, greenish-white, membranous; petiole short; blade lanceolate to rhomboid, 2.5–3.5 cm long, base gradually narrowed, apex acute, margin entire to pinnatisect. Inflorescence a lax raceme 10–20 cm long. Flowers polygamous (bisexual or unisexual), in clusters of 2–3; perianth tubular, 5-lobed, lobes pinkish or white, 4 mm long; stamens 8; ovary included in the perianth tube, styles 3, filiform, connate at base, stigma capitate. Fruit an indehiscent, usually trigonous (sometimes rounded), ovoid nut, 8 mm long, enclosed by the perianth tube, with wings up to 6 mm broad, but sometimes the wings are absent; the faces of the fruit often have a small spreading prickle at about one-third distance from the base. Seed similar in shape to the nut.
Oxygonum comprises about 30 species and is confined to tropical Africa, South Africa and Madagascar.
Oxygonum alatum appears in the rainy season as an annual on deep sands.
Oxygonum alatum is not cultivated; it is only collected from the wild.
Genetic resources and breeding
Oxygonum alatum is rather widespread and does not seem in danger of genetic erosion.
Oxygonum alatum will remain locally a useful vegetable, particularly in dry areas with poor sandy soils.
Major references
• Baker, J.G. & Wright, C.H., 1909–1913. Polygonaceae. In: Thiselton-Dyer, W.T. (Editor). Flora of tropical Africa. Volume 6(1). Lovell Reeve & Co., London, United Kingdom. pp. 98–120.
• Graham, R.A., 1957. A revision of Oxygonum (Polygonaceae – Polygoneae). Kew Bulletin 12: 145–172.
• van Wyk, B.E. & Gericke, N., 2000. People’s plants: a guide to useful plants of southern Africa. Briza Publications, Pretoria, South Africa. 351 pp.
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. Oxygonum alatum Burch. In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.