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Pentanisia schweinfurthii Hiern

Protologue
Oliv., Flora trop. Afr. 3: 131 (1877).
Family
Rubiaceae
Chromosome number
2n = 40
Synonyms
Pentanisia crassifolia K.Krause (1907), Pentanisia variabilis auct. non Harv.
Vernacular names
Rhodesian forget-me-not (En). Mlangaze (Sw).
Origin and geographic distribution
Pentanisia schweinfurthii is widespread in tropical Africa, from Nigeria and Sudan south to Angola and Mozambique.
Uses
Crushed leaves and tips of flowering shoots of Pentanisia schweinfurthii are locally eaten as a cooked vegetable, particularly in the dry season, e.g. in Tanzania, Malawi and Zambia. In Malawi the ash of the burned plant is used as salt. A decoction of leaves and roots is taken in eastern Africa to stop diarrhoea.
Botany
Perennial herb up to 25 cm tall, with several stems arising from a woody rootstock, glabrous to hairy. Leaves opposite, simple; stipules with 2–4 deltoid lobes; petiole up to 2 mm long; blade very variable, round to elliptical-obovate or linear, 0.3–5.5 cm × 0.2–2 cm, base cuneate, apex acute to obtuse, usually glabrous. Inflorescence head-like and up to 2.5 cm long, or branched and spike-like and 2–3.5 cm long; peduncle up to 7 cm long. Flowers bisexual, regular, usually 5-merous; calyx tubular, tube squarish, 1.5 mm long, longest lobe up to 3.5 mm × 1 mm, other lobes much smaller; corolla tubular, bright blue, white, pale lilac or purple, tube up to 13 mm long, densely hairy at the throat, lobes ovate-oblong-lanceolate, 2–6 mm × 1–2 mm; ovary 2-celled, style filiform, exserted 2–4 mm in long-styled flowers, stigma divided into 2 filiform lobes up to 2 mm long. Fruit capsule-like, ovoid, 1.5–2.5 mm × 1.5–2 mm, thin-walled, indehiscent, usually 2-seeded. Seeds broadly elliptical in outline, concave-convex, 2 mm × 1.5 mm × 0.5 mm, yellow brown, finely marked with brown.
Pentanisia is confined to tropical Africa (including Madagascar) and comprises 15 species.
Ecology
Pentanisia schweinfurthii occurs in grasslands and woodlands, always in areas subject to burning; it is fire-resistant. In eastern Africa it grows at altitudes of 800–2250 m. It is also a common weed of cultivation.
Management
Pentanisia schweinfurthii is collected from the wild and is not cultivated.
Genetic resources and breeding
Pentanisia schweinfurthii is widespread and not in danger of genetic erosion.
Prospects
Pentanisia schweinfurthii will remain a minor vegetable, most important in the dry season when other vegetables are scarce. Its nutritional and medicinal value deserve more research.
Major references
• Burkill, H.M., 1997. The useful plants of West Tropical Africa. 2nd Edition. Volume 4, Families M–R. Royal Botanic Gardens, Kew, United Kingdom. 969 pp.
• Verdcourt, B., 1952. A revision of certain african genera of herbaceous Rubiaceae. 1. The genus Pentanisia Harvey. Bulletin du Jardin Botanique de L'Etat (Bruxelles) 22: 233–286.
• Verdcourt, B., 1976. Rubiaceae (part 1). In: Polhill, R.M. (Editor). Flora of Tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 414 pp.
• 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
• Kokwaro, J.O., 1993. Medicinal plants of East Africa. 2nd Edition. Kenya Literature Bureau, Nairobi, Kenya. 401 pp.
• Malaisse, F., Grégoire, J., Nyembo, L. & Robbrecht, E., 1979. A propos d'une recherche d'alcaloïdes dans les Rubiaceae du Shaba méridional (Zaïre). Bulletin du Jardin Botanique National de Belgique 49: 165–177.
• Puff, C. & Robbrecht, E., 1989. A survey of the Knoxieae (Rubiaceae-Antirheoideae). Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie 110: 511–558.
• Verdcourt, B., 1989. Rubiaceae (Rubioideae). In: Launert, E. (Editor). Flora Zambesiaca. Volume 5, part 1. Flora Zambesiaca Managing Committee, London, United Kingdom. 210 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. Pentanisia schweinfurthii Hiern In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.