1. Family: Urticaceae Juss.
    1. Genus: Obetia Gaudich.
      1. Obetia radula (Baker) Baker ex B.D.Jacks.

        Tree-huggers beware – even the trunk of this tree has vicious stinging hairs, which cause both pain and intense itching. Think of European stinging nettle ( Urtica dioica), which is from the same plant family (Urticaceae), and multiply! But from several steps away it is a pretty tree, looking a bit like a papaya tree ( Carica papaya). It grows on rocky hillsides in East Africa and Madagascar and, amazingly, people have found a way of using the bark fibres for basketry and rope-making.

    [FTEA]

    Urticaceae, I. Friis University of Copenhagen, Denmark. Flora of Tropical East Africa. 1989

    Habit
    Sparsely branched tree, 5–13 m. high, presumably dioecious; trunk 0.2–0.5 m. in diameter at base, with main branching points either near the base or at the top, ultimate branchlets ± 0.8 cm. thick when dry, probably more when fresh, covered with large persistent stipules and stinging hairs; wood soft and with much juice in the thick bark and the wide pith; bark grey or brown, smooth to flaky, with very noticeable leaf-scars on the branches; the whole plant has an appearance not unlike a paw-paw, probably always completely deciduous for part of the year.
    Leaves
    Leaves always clustered at the end of the branches; stipules large, ovate to subcircular, 1.5–2.5 cm. long, 1.2–1.8 cm. wide, acute to acuminate, glabrous or ciliate, long-persistent, green but withering brownish; petiole 8–15 cm., pubescent and with many stinging hairs up to 2.5 mm. long; lamina ovate in outline, usually bullate, 15–25 cm. long and wide, palmately lobed or divided, rarely ± entire, with each lobe triangular, unlobed to ± clearly palmately lobed, base deeply cordate, margin (also of the lobes) serrate, apex (also of lobes) acuminate; lateral nerves 5–7 pairs, basal pair reaching the tip of the basal lobes; upper surface with short hairs and scattered stinging hairs, lower surface densely pubescent, and with scattered stinging hairs on the nerves; cystoliths punctiform, visible from above.
    Inflorescences
    Inflorescences in the axils of the current leaves, rarely persisting after the leaves have fallen, profusely branched panicles up to ± 20 cm. long, on peduncles up to ± 5 cm. long, pubescent and with numerous stinging hairs, flowers in small clusters at the branching points or scattered along the axes; ♂ and ♀ rather similar.
    Flowers
    Male flowers subsessile; perianth globular, up to ± 2 mm. in diameter, 5-merous, with rudimentary ovary present. Female flowers subsessile, 4-merous, perianth up to ± 0.8 mm. in diameter, compressed; stigma prominent penicillate, the whole flower yellow.
    Male
    Male flowers subsessile; perianth globular, up to ± 2 mm. in diameter, 5-merous, with rudimentary ovary present.
    Female
    Female flowers subsessile, 4-merous, perianth up to ± 0.8 mm. in diameter, compressed; stigma prominent penicillate, the whole flower yellow.
    Fruits
    Achene ± 1–1.5 mm. long.
    Figures
    Fig. 3.
    [KSP]

    Kew Species Profiles

    General Description
    The stinging-nettle tree looks a bit like a papaya tree - but it does what its name suggests!

    Tree-huggers beware – even the trunk of this tree has vicious stinging hairs, which cause both pain and intense itching. Think of European stinging nettle ( Urtica dioica), which is from the same plant family (Urticaceae), and multiply! But from several steps away it is a pretty tree, looking a bit like a papaya tree ( Carica papaya). It grows on rocky hillsides in East Africa and Madagascar and, amazingly, people have found a way of using the bark fibres for basketry and rope-making.

    Species Profile

    Geography and distribution

    Obetia radulais known from only a rather narrow geographic band, stretching from eastern Congo-Kinshasa, through Rwanda, Burundi, Uganda, Kenya and north Tanzania, to Madagascar. It has been found at 500–2,000 m above sea level.

    Description

    Overview: A tree 5–13 m tall, with a sparsely-branched trunk up to 50 cm across, covered in stinging hairs.

    Leaves: The leaves are clustered at the branch ends, and are much lobed, 15–25 × 15–25 cm, with stinging hairs all over.

    Flowers: The flowers are yellow-green and the male and female flowers are usually borne on separate trees in the axils of leaves. The male flowers are borne in groups up to 10 cm long, and are about 2 mm across. The female flowers are borne in groups up to 30 cm long, and are up to 8 mm across.

    Fruits: The fruits are minute (less than 2 mm long).

    Threats and conservation

    Stinging-nettle tree occurs over a wide area, and there are no specific threats to either its habitat or the species itself. Hence, although an official conservation assessment has not been carried out, it is thought likely this species will be assessed as of Least Concern.

    Uses

    The stem fibres of Obetia radula are used to make rope and baskets. Some tribes use the roots as a remedy against barrenness (female infertility). The leaf is used in East Africa to deter rats and moles, as contact with the stinging hairs on the leaves causes intense itching in animals. In Madagascar the bark fibre was formerly used to ignite fires.

    This species at Kew

    Pressed and dried specimens of Obetia radula are held in the Herbarium, where they are available to researchers from around the world by appointment. The details of some of these specimens, including images, can be seen online in the Herbarium Catalogue.

    View details and images of specimens

    Distribution
    Kenya, Tanzania
    Ecology
    Rocky hillsides in bushland.
    Conservation
    Not yet assessed according to IUCN Red List criteria, but thought likely to be of Least Concern.
    Hazards

    The trunk and leaves bear stinging hairs, which can cause pain and intense itching to humans and animals on contact.

    [KSP]
    Use
    Rope-making, basketry, medicinal.

    Images

    Distribution

    Found In:

    Aldabra, Madagascar, Rwanda, Uganda

    Common Names

    English
    Stinging-nettle tree

    Obetia radula (Baker) Baker ex B.D.Jacks. appears in other Kew resources:

    Date Identified Reference Herbarium Specimen Type Status
    Aug 18, 1982 Baron, R. [1820], Madagascar K000242833 syntype
    Aug 18, 1982 Bojer [s.n.], Madagascar K000242834 syntype
    Aug 18, 1982 Parker, G.W. [1721], Madagascar K000242835 syntype
    Aug 18, 1982 Madagascar K000242838 Unknown type material
    Aug 18, 1982 Langley Kitching [s.n.], Madagascar K000242839 Unknown type material
    Aug 18, 1982 Baron, R. [1729], Madagascar K000242840 syntype
    Aug 18, 1982 Baron, R. [1822], Madagascar K000242841 syntype
    Baron, R. [1721], Madagascar K000242836 syntype
    Langley Kitching [s.n.s.n.], Madagascar K000242837

    First published in Index Kew. 2: 323 (1895)

    Accepted in:

    • [3] (1994) Flore des Seychelles Dicotylédones: 1-663. Orstom Editions.
    • [7] Troupin, G. (ed.) (1978) Flora du Rwanda 1: 1-413. Musee Royal de l'Afrique Centrale.

    Literature

    • [1] Kalema, J. & Beentje, H. (2012) Conservation checklist of the trees of Uganda . Kew Publishing, Royal Botanic Gardens, Kew.
    • [2] Brink, M. (2009). Obetia radula (Baker) B.D.Jacks. [Internet] Record from Protabase. Brink, M. & Achigan-Dako, E.G. (editors). PROTA (Plant Resources of Tropical Africa), Wageningen, Netherlands.  (Accessed 11 March 2011).
    • [4] Beentje, H.J. (1994). Kenya Trees, Shrubs and Lianas. National Museums of Kenya, Nairobi.
    • [5] Friis, I. (1989). Flora of Tropical East Africa: Urticaceae. Balkema, Rotterdam.
    • [6] Friis, I. (1983). A synopsis of Obetia (Urticaceae). Kew Bulletin 38: 221–228.

    Sources

    Flora of Tropical East Africa
    [A] http://creativecommons.org/licenses/by-nc-sa/3.0

    International Plant Names Index
    The International Plant Names Index (2016). Published on the Internet http://www.ipni.org
    [B] © Copyright 2016 International Plant Names Index. https://creativecommons.org/licenses/by/3.0

    Kew Species Profiles
    Kew Species Profiles
    [C] http://creativecommons.org/licenses/by-nc-sa/3.0
    [D]

    World Checklist of Selected Plant Families
    World Checklist of Selected Plant Families(2016). Published on the Internet http://apps.kew.org/wcsp/
    [E] See http://kew.org/about-kew/website-information/legal-notices/index.htm You may use data on these Terms and Conditions and on further condition that: The data is not used for commercial purposes; You may copy and retain data solely for scholarly, educational or research purposes; You may not publish our data, except for small extracts provided for illustrative purposes and duly acknowledged; You acknowledge the source of the data by the words "With the permission of the Trustees of the Royal Botanic Gardens, Kew" in a position which is reasonably prominent in view of your use of the data; Any other use of data or any other content from this website may only be made with our prior written agreement. http://creativecommons.org/licenses/by-nc-sa/3.0
    [F] © Copyright 2016 International Plant Names Index and World Checkist of Selected Plant Families. https://creativecommons.org/licenses/by/3.0