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Thunbergia lancifolia T.Anderson

Protologue
Journ. Linn. Soc. Bot. 7: 19 (1863).
Family
Acanthaceae
Origin and geographic distribution
Thunbergia lancifolia occurs in DR Congo, Burundi, Tanzania, Malawi, Zambia, Angola, Zimbabwe and Mozambique.
Uses
In Malawi and Zimbabwe the young leaves of Thunbergia lancifolia are collected from the wild, cooked and used as a vegetable, although they are rather tough. Sometimes the leaves are cooked in the sour liquid (‘matsukwa’) that remains after soaking maize, sometimes mixed with young leaves of sweet potato. This latter product is not much liked and only cooked occasionally. The flowers are rich in nectar and sucked for their sweetness. In Mozambique the rhizome is applied as dried powder on swellings, and an extraction in water is drunk against bilharzia. Ash of the burned rhizome is eaten with food by women as contraceptive. In DR Congo macerated leaves are applied to burns. In Zimbabwe an infusion of the plant is used to treat skin diseases and after soaking the leaves for some hours, the extract liquid is used as hair shampoo.
Properties
No data on nutritive value or chemical composition are available for Thunbergia lancifolia. In Thunbergia alata Sims, of which the leaves are also eaten but which is more important as an ornamental, phenolic compounds (caffeoylmalic acid, feruloylmalic acid and p-coumaroylmalic acid) have been found in the leaves, and in several other species iridoid glycosides (e.g. stilbericoside).
Botany
Erect, branched, perennial herb or shrub up to 90 cm tall, glabrous, with woody rhizome; stems grooved. Leaves decussately opposite, simple, subsessile; blade linear-lanceolate to elliptical, oblanceolate or obovate, 4–19 cm × 1–4 cm, base attenuate, sometimes auriculate, apex acute, margin entire, glabrous or glabrescent, glossy at both surfaces. Flowers solitary, axillary, zygomorphic, large, subtended by 2 ovate bracts 3 cm × 2 cm; pedicel up to 3 cm long in flower, 6.5 cm in fruit; calyx persistent, connate at base, with unequal, short, irregular teeth; corolla tubular, 5-lobed, tube c. 3 cm × 1.5 cm, lobes unequal, c. 2 cm long, lavender to reddish, with yellow-orange throat; stamens 4, didynamous, included in tube, anthers with a spur above, hairy below, the ventral pair with a straight spur below; ovary superior, 2-celled, style cylindrical, stigma funnel-shaped, triangular. Fruit a finely pubescent capsule, subglobose at base and 1.5 cm in diameter, with a prominent beak 1.5 cm long, splitting in 2 halves at maturity.
Thunbergia is a large, poorly known genus, comprising about 100 species, and confined to the Old World tropics and subtropics. In Malawi the leaves of Thunbergia oblongifolia Oliv. (an erect woody herb, also known from Tanzania) are similarly used as a vegetable. Thunbergia aurea N.E.Br., occurring in Botswana, Namibia and South Africa, also has edible leaves. Several Thunbergia species are popular ornamentals, e.g. Thunbergia alata Sims (’black-eyed Susan’) in eastern and southern Africa, and Thunbergia grandiflora (Roxb.) Roxb. (’blue trumpet vine’), introduced and naturalized, for example, in Nigeria. Both latter species have edible leaves.
Ecology
Thunbergia lancifolia occurs in dry, regularly burned savanna and open woodland, at 1000–1800 m altitude.
Genetic resources and breeding
Thunbergia lancifolia is rather widespread and not in danger of genetic erosion.
Prospects
Thunbergia lancifolia will remain a minor vegetable, most probably only locally eaten in times of food scarcity. The large, showy, blue flowers with orange-yellow throat and the erect, short, shrubby habit make it a potential ornamental.
Major references
• Burkill, H.M., 1985. The useful plants of West Tropical Africa. 2nd Edition. Volume 1, Families A–D. Royal Botanic Gardens, Kew, United Kingdom. 960 pp.
• 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.
• Jansen, P.C.M. & Mendes, O., 1983. Plantas medicinais, seu uso tradicional em Moçambique. Volume 1. Gabinete de Estudos de Medicina Tradicional, Ministério da Saúde, Maputo, Moçambique. 216 pp.
• Tredgold, M.H., 1986. Food plants of Zimbabwe. Mambo Press, Gweru, Zimbabwe.153 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
• Benoist, R., 1967. Acanthacées (Acanthaceae). Flore de Madagascar et des Comores (plantes vasculaires), famille 182. Muséum National d’Histoire Naturelle, Paris, France. 230 pp.
• Heine, H., 1963. Acanthaceae. In: Hepper, F.N. (Editor). Flora of West Tropical Africa. Volume 2. 2nd Edition. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 391–432.
• Housti, F., Andary, C., Gargadennec, A. & Amssa, M., 2002. Effects of wounding and salicylic acid on hydroxycinnamoylmalic acids in Thunbergia alata. Plant Physiology and Biochemistry (Paris) 40 (9): 761–769.
• Jensen, S.R. & Nielsen, B.J., 1989. Iridoids in Thunbergia species. Phytochemistry 28(11): 3059–3062.
• Meyer, P.G., 1968. Acanthaceae. Prodromus einer Flora von Südwestafrika. No 130. J. Cramer, Germany. 65 pp.
• Retief, E. & Reyneke, W.F., 1984. The genus Thunbergia in southern Africa. Bothalia 15: 107–116.
• Schönenberger, J., 1999. Floral structure, development and diversity in Thunbergia (Acanthaceae). Botanical Journal of the Linnean Society 130: 1–36.
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. Thunbergia lancifolia T.Anderson In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.