Prota 2: Vegetables/Légumes
Oliv., Flora trop. Afr. 3: 131 (1877).
2n = 40
Pentanisia crassifolia K.Krause (1907), Pentanisia variabilis auct. non Harv.
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.
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.
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.
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.
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.
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.
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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.