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Lactuca inermis Forssk.

Protologue
Fl. aegypt.-arab.: 144 (1775).
Family
Asteraceae (Compositae)
Chromosome number
n = 12
Synonyms
Lactuca capensis Thunb. (1800).
Origin and geographic distribution
Lactuca inermis is widely distributed in tropical Africa, Madagascar, South Africa and Yemen.
Uses
The leaves and young shoots of Lactuca inermis are lightly boiled and eaten in Zimbabwe. In Lesotho the young plants are eaten as a potherb. In Madagascar Lactuca inermis is used as a vegetable as well.
An infusion of the leaves (northern Nigeria) or of the boiled roots (Kenya) is drunk as a cure for venereal diseases. In DR Congo the pulverized root is applied to sores, ulcers, leprosy and eczema. The leaves, pounded with natron, are given to horses as a vermifuge in Nigeria.
Botany
Perennial, erect herb 5–150(–240) cm tall, sparsely branched, with long, thick taproot. Leaves alternate, sessile, scattered along the stem or crowded on the lower stem; blade lanceolate, sometimes lobed, 5–20 cm × 0.3–1.6 cm (including lobes up to 7 cm wide), base semi -amplexicaul in lower leaves, sagittate higher up, apex acute or mucronate, margin entire or remotely denticulate. Inflorescence a lax or congested panicle of 3–100 heads, with sagittate bracts. Florets 2–14 per head; corolla blue or mauve, rarely pink, yellow or white, tube cylindrical, 4–6 mm long, ligule 6–11 mm × 1–2.5 mm. Fruit a dark-brown to black achene with white pappus.
Variability in Lactuca inermis, especially in habit and flower colour, is considerable but continuous.
The leaves of Lactuca schweinfurthii Oliv. & Hiern are eaten raw in DR Congo. A related species, Pterocypsela indica (L.) C.Shih (synonym: Lactuca indica L.; Indian lettuce, wild lettuce) originates from China and is found, most likely as the result of introduction, in the Indian Ocean Islands (Comoros, Madagascar, Seychelles and Mauritius), Mozambique and South Africa. In Asia it is widely used as a vegetable but no uses are recorded for tropical Africa. Although potentially a valuable vegetable, it should not be promoted because of its weedy nature. The sap of the inflorescence stalk of Lactuca schulzeana Büttner, a species restricted to Angola and DR Congo, is given to children as a vermifuge.
Ecology
Lactuca inermis is a pioneer species found in grassland, fallow land and roadsides. Its altitudinal range is (650–)1000–2800(–3450) m in East Africa and 1200–2000 m in Madagascar. It flowers throughout the year, often without leaves being present.
Genetic resources and breeding
Lactuca inermis occurs widespread in Africa and is not liable to genetic erosion. Although wild Lactuca species might be interesting for breeding, the African species are under-represented in genebanks. Only 3 accessions of Lactuca inermis could be traced and even these might well be duplicates of 1 entry.
Prospects
Interest in Lactuca inermis as a vegetable will remain localized. It might attract attention from lettuce (Lactuca sativa L.) breeders as a source of pest and disease resistance and heat tolerance. The medicinal uses might be substantiated by research into its chemistry.
Major references
• Beentje, H.J., 2000. Compositae (part 1). In: Beentje, H.J. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. pp. 1–313.
• 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.
• Kokwaro, J.O., 1993. Medicinal plants of East Africa. 2nd Edition. Kenya Literature Bureau, Nairobi, Kenya. 401 pp.
• Tredgold, M.H., 1986. Food plants of Zimbabwe. Mambo Press, Gweru, Zimbabwe.153 pp.
Other references
• Humbert, H., 1963. Composées (Compositae). Flore de Madagascar et des Comores (plantes vasculaires), famille 189, tome 3. Firmin-Didot et cie., Paris, France. pp. 623–911.
• Lawalrée, A., Dethier, D. & Gilissen, E., 1986. Compositae (Première partie: sous-famille Cichorioideae). In: Bamps, P. (Editor). Flore d’Afrique centrale. Spermatophytes. Jardin botanique national de Belgique, Brussels, Belgium. 72 pp.
• Roemantyo, 1993. Lactuca indica L. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 184–186.
Author(s)
C.H. Bosch
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:
Bosch, C.H., 2004. Lactuca inermis Forssk. In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.