1. Family: Lamiaceae Martinov
    1. Genus: Plectranthus L'Hér.
      1. Plectranthus esculentus N.E.Br.

        Despite the common names suggesting this species is a type of potato, Plectranthus esculentus is actually a member of the mint family (Lamiaceae) and is not in the same family (Solanaceae) as the potato we commonly eat. Other names found in older literature for this species are Coleus dazo, Coleus esculentus, and Plectranthus floribundus.

    [KSP]

    Kew Species Profiles

    General Description

    Despite the common names suggesting this species is a type of potato (Livingstone potato), Plectranthus esculentus is actually a member of the mint family (Lamiaceae) and is not in the same family (Solanaceae) as the potato we commonly eat. Other names found in older literature for this species are Coleus dazo, Coleus esculentus, and Plectranthus floribundus.

    Livingstone potato is cultivated for food in parts of Africa. It is thought that cultivation began through selection of wild populations in the Upper Niger valley of the Hausaland (Nigeria) and in the Central African Republic.

    Species Profile
    Geography and distribution

    Plectranthus esculentus occurs in dry wooded areas in equatorial Africa, and southwards to Angola, the eastern Transvaal and KwaZulu-Natal coast of South Africa, and Swaziland.

    Description

    This sparsely branched perennial herb grows up to 2 m tall and produces a cluster of small, branching, edible tubers (swollen underground stems) at the base of the stem. Flowers are produced before the leaves and the stems are leafless while the plant is in flower. The yellow flowers are two-lipped, and carried on short, densely crowded branches. The leaves have toothed edges and brown gland-dots on the undersurface.

    Threats and conservation

    This species is not considered threatened, although it has been reported that its cultivation as a traditional crop plant has declined in some parts of Africa as a result of the social stigma attached to native plants, and a growing preference for exotic crops. However, it is being developed for the commercial market in southern Africa.

    Uses

    Livingstone potato is cultivated in Africa for its edible tubers, each of which may weigh up to 1.8 kg. The tubers persist underground even when the plant lacks leaves. They are dug up and usually boiled or roasted, and are often eaten as a substitute for sweet potato ( Ipomeas batatas ) or potato ( Solanum tuberosum ). Researchers in South Africa are continuing centuries of selection for its edible tubers so as to optimise the crop for local farmers.

    Preliminary biochemical analysis of the species suggests it has high nutritional value, being rich in carbohydrates, vitamin A and minerals, and hence is valuable in times of food shortage. This is especially true as the plant is well suited to local environmental conditions in areas where it has a long tradition of cultivation.

    Plectranthus esculentus is one of the most frequently used of the 21 species of Plectranthus employed in the treatment of disorders of the digestive system. It is also used in eastern and southern Africa as an antihelmintic to treat intestinal worms. It has cytotoxic and anti-tumour activity.

    Further research is needed to determine whether this species is of wider medicinal value. The related species Plectranthus barbatus contains the compound coleonol, which is a potent stimulant that has potential for the treatment of hypertension, glaucoma, asthma and certain cancers.

    Millennium Seed Bank: Seed storage

    Kew's Millennium Seed Bank Partnership aims to save plant life world wide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.

    Number of seed collections stored in the Millennium Seed Bank: Six

    Germination testing: Successful

    Cultivation

    Livingstone potato can be propagated from tubers and small axillary bulbils. Tubers should be planted in the spring for harvest the following autumn (tubers can be harvested 180 to 200 days after planting). The crop is reportedly very hardy, but the optimal conditions for growth are a temperature of 15-28 ˚C, annual rainfall of 700 to 1,100 mm and a soil pH of 6.5 to 7. Yields of 2 - 6 tonnes per hectare have been recorded.

    Livingstone potato at Kew

    Dried and alcohol-preserved specimens of Plectranthus esculentus are stored in the Herbarium (one of the behind-the-scenes areas of Kew), where they are made available to researchers from around the world by appointment. The details of 15 of these specimens, including some images, can be seen in the Herbarium Catalogue.

    Livingstone potato tubers are also held in Kew's Economic Botany Collection. Detailed information on this specimen can be viewed using ePIC(the electronic Plant Information Centre).

    Research on Plectranthus at Kew

    The genus Plectranthus has been the subject of much recent research at Kew, including a survey of its ethnobotanical uses, carried out in collaboration with Dr Catherine Lukhoba of Nairobi University, Kenya.

    Three species of Plectranthus are used for their edible tubers in tropical Africa. It is likely that a number of African tuber-producing species were formerly extensively cultivated and have come to be displaced by the most successful, or culturally popular, ones.

    Many of the native crops that sustained local populations and early civilisations for centuries are now neglected and unstudied. Some of these crops, including Plectranthus esculentus , have contributed significantly to rural diets and are well adapted to different environmental conditions. Further research on this subject could therefore be of great benefit.

    Distribution
    Angola, South Africa
    Ecology
    Grassland, open Isoberlinia, Brachystegia and Uapaca woodland, often in rocky areas. Also found in cultivation.
    Conservation
    Not threatened.
    Hazards

    None known.

    [FWTA]

    Labiatae, J. K. Morton. Flora of West Tropical Africa 2. 1963

    Habit
    Perennial with herbaceous erect stems
    Indumentum
    Rather coarsely pilose with whitish hairs
    Flowers
    Flowers yellow 1/2-2/3 in. long
    Roots
    Root elongated-tuberous
    Note
    Often cultivated.

    Images

    Distribution

    Found In:

    Angola, Botswana, Burkina, Cameroon, Central African Repu, Congo, KwaZulu-Natal, Malawi, Mali, Mozambique, Nigeria, Northern Provinces, Swaziland, Tanzania, Uganda, Zambia, Zaïre, Zimbabwe

    Introduced Into:

    Chad

    Common Names

    English
    Livingstone potato

    Plectranthus esculentus N.E.Br. appears in other Kew resources:

    Date Identified Reference Herbarium Specimen Type Status
    Jan 1, 1894 Wood, J.M. [3633], KwaZulu-Natal K000975993 Unknown type material
    Jan 1, 1894 Wood, J.M. [3633], KwaZulu-Natal K000975994 Unknown type material
    Jan 1, 1894 Wood, J.M. [3633], KwaZulu-Natal K000975995 Unknown type material
    Baines, T. [s.n.], Zimbabwe K000430739 Unknown type material
    Johnston, H.H. [s.n.], Angola K000430740
    Kirk [s.n.], Malawi K000430741
    K000430742
    Meller, C.J. [2], Malawi K000430743 Unknown type material
    Thomson [s.n.] K000430744 Unknown type material
    Scott, L. [s.n.], Malawi K000430745 Unknown type material
    Carson, A. [36] K000430746 Unknown type material
    Chevalier, A. [s.n.], Congo, DRC K000431865
    Hepper, N.K. [1945], Cameroon 1238.000
    Wood, J.M. [646], South Africa K000430828 Unknown type material
    Groom, W. [3843], South Africa K000430829 Unknown type material
    Wood, J.M. [s.n.], South Africa K000430830

    First published in Bull. Misc. Inform. Kew 1894: 12 (1894)

    Accepted in:

    • [1] (2013) Flora Zambesiaca 8(8): 1-346. Royal Botanic Gardens, Kew
    • [2] (2013) PhytoKeys 23: 1-18
    • [3] (2009) Flora of Tropical East Africa
    • [4] Timberlake, J.R., Bayliss, J., Alves, T., Francisco, J., Harris, T., Nangoma, D. & de Sousa, C. (2009) Biodiversity and Conservation of Mchese Mountain, Malawi. Report produced under the Darwin Initiative Award 15/036 . Royal Botanic Gardens, Kew
    • [5] (2008) Strelitzia 22: 1-279. National Botanical Institute, Pretoria
    • [6] (2006) Scripta Botanica Belgica 34: 1-199
    • [9] van Jaarsveld, E. (2006) The Southern African Plectranthus and the art of turning shade to glade . Ferwood Press, Simon's Town, South Africa
    • [11] Calane da Silva, M., Izdine, S. & Amuse, A.B. (2004) A Preliminary Checklist of the Vascular Plants of Mozambique . SABONET, Pretoria
    • [13] Govaerts, R. (2003) World Checklist of Selected Plant Families Database in ACCESS . The Board of Trustees of the Royal Botanic Gardens, Kew
    • [15] Lebrun, J.P., Toutain, B., Gaston, A. & Boudet, G. (1991) Catalogue des Plantes Vasculaires du Burkina Faso . Institut d' Elevage et de Médecine Vétérinaire des Pays Tropicaux, Maisons Alfort

    Literature

    • [7] Allemann, J. & Hammes, P. S. (2006). Effect of photoperiod on tuberization in the Livingstone potato ( Plectranthus esculentus N.E.Br. Lamiaceae). Field Crop. Res. 98: 76-81.
    • [8] Lukhoba, C.W., Simmonds, M.S.J. & Paton, A.J. (2006). Plectranthus: A review of ethnobotanical uses. J. Ethnopharmacology. 103: 1-24.
    • [10] Van Wyk, B. (2005). Food Plants of the World. Timber Press, Oregon.

    • [12] Allemann, J., Robbertse, P. & Hammes, P. (2003). Organographic and anatomical evidence that the edible storage organs of Plectranthus esculentus N. E. Br. (Lamiaceae) are stem tubers [online] Field Crop. Res. Volume 83: Issue 1 pp. 35-39.
    • [14] Kyesmu, P.M. (1994). Plectranthus esculentus N.E.Br. A minor tuber crop in dire need of rescue from extinction. Lamiales Newsl. 4: 3-4.
    • [16] Burkill, H.M. (1985). The useful plants of west tropical Africa, Vol 3. Royal Botanic Gardens, Kew, London.
    • [17] in Kew Bull. 1894: 12.

    Sources

    Flora of West Tropical Africa
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    Kew Names and Taxonomic Backbone
    The International Plant Names Index and World Checklist of Selected Plant Families (2017). Published on the internet at http://www.ipni.org and http://apps.kew.org/wcsp
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    [C] © Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

    Kew Species Profiles
    Kew Species Profiles
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