Tree is usually up to 5m high and the dark trunk is longitudinally furrowed. Leaves are trifoliate. The dioecious, regular Flowers are 5-merous. Fruit: diamond shaped Drupe + reniform Seeds.
Searsia leptodictya, Rhus leptodictya, Rhus rhombocarpa, Rhus guienzii.
RSA Tree No. 387.
Common names: Mountain Karree, Rock Karree-Searsia, Rock Karee, Berg Karee, False Karee.
Family: Anacardiaceae (Mango family), which has about 83 genera and 850+ species – including Cashew). Resin canals are present and woolly stellate hairs cover all young parts. Leaves lack stipules. They are deciduous or evergreen and usually alternate. Leaves are simple, trifoliate or digitally compound and imparipinnate. When present, leaflets are usually opposite. Crushed leaves may smell of turpentine. Trees are monoecious or dioecious with occasional bisexual Flowers. Flowers are small, usually regular and unisexual. The Calyx has 4-7 sepals and there are 4-7 Petals. The number of Stamens is the same as, or twice the number of petals and the Anthers are versatile. The superior Ovary has up to 4 locules, each with a single ovule. The 1-5 Styles are free or connate and separated at the base. Fruit is usually an indehiscent fleshy drupe with a single Seed. The southern Africa genera include Harpephyllum, Lannea, Loxostylis, Ozoroa, Sclerocarya and Searsia.
Name derivation: Searsia – Named after Paul Sears, an American ecologist (December 17, 1891 – April 30, 1990). leptodictya – fine or thin – referring to the network veins in the leaflets. There are about 80 species in the genus Searsia in the RSA.
Conservation Status: L C. (Least Concern). 2009.
This spineless Tree may reach 9m high (usually half this height) or grow a spreading shrub. The Trunk is longitudinally furrowed and dark grey to brown (similar to S. lancea). Branches are smooth, reddish brown and tend to hang down. Branchlets (usually applied to branches of the current or preceding year) may have velvety hairs. Lenticels (a usually raised corky oval or elongated area on the plant that allows the uncontrolled interchange of gases with the environment) are present on the twigs.
On this deciduous tree, the Leaves are light green, thinly textured and trifoliate (compound leaf with 3 leaflets). Leaflets are relatively narrow to lanceolate and pale olive green above and slightly lighter below. The terminal or middle leaflet is up to 11 x 2,5cm and lateral leaflets are smaller. They are situated close to 90 to the central leaflet. All veins are more visible above and only the midrib is clearly visible below. The Apex is broadly to narrowly tapering and may end in a sharp point. The Base tapers. Margins are usually shallowly toothed or scalloped from base to apex and leaflets are wavy. Leaflets may also be entire (with a continuous margin, not in any way indented but may be hairy). The thin, wingless Petiole (leaf stalk) is up to 4,5cm long and may be reddish. Petiolules (leaflet stalks) and Stipules (basal appendage of the petiole) are absent. Crushed leaves have a resinous smell.
The small Flowers are visible because of their large numbers. They are dioecious (having male and female parts on separate plants). They are greenish or yellowish white and arranged in Panicles (indeterminate, branched inflorescence with stalked flowers) which are up to 12cm long. Individual flowers are unisexual and actinomorphic (regular, symmetrical. The Perianth – the calyx and corolla are divisible into 3 or more identical sectors or mirror images). A roughly circular Disc (a more or less fleshy or elevated development of the receptacle) is present. The Calyx has 5 Sepals which are joined at the base and the Corolla has 5 free Petals. Male flowers lack an Ovary. Here there are 5 Stamens with free filaments. The Anthers have 2 Thecae (pollen sacs) present and dehiscence is through longitudinal slits. The Female flowers have a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) containing a superior Ovary. 3 free Styles with capitate (formed like a head) stigmas are present. 5 Staminodes (sterile stamens) may also be present. (Sep-Apr).
The Fruit is a flattened shiny, diamond shaped Drupe (stone fruit like a tiny peach but much smaller in this case) with a thin pulp layer. It is up to about 6 x 2mm. Mature fruits are yellow to red-brown. (Mar-Jun). Birds disperse the reniform (kidney-shaped) Seeds that survive passing through their digestive system. These seeds lack endosperm (the starch and oil-containing tissue of many seeds; often referred to as the albumen).
Distribution & Ecology
This plant is found up to an altitude of 2 000m in rocky places, particularly in granitic (an igneous rock that develops underground when silica rich molten rock cools) areas. They also occur in open woodland, forest margins and in grasslands – Central Free State, Northern Cape, Gauteng – common round Johannesburg and Pretoria, Mpumalanga, Swaziland, Zimbabwe, Mozambique, Botswana and Malawi. Many Birds, including doves, bulbuls, mousebirds and white-eyes, eat fruit. Eland, Giraffe, Kudu and Blue duiker consume the leaves. Leafy green Branches from Searsia leptodictya are used to line the nests of Verreaux’s Eagle. This is because they have a disinfectant property that helps protect the nests from disease.
This Tree is quick growing from Seed and the plant is drought and frost resistant. It can grow on a variety of soils and does not have an aggressive root system. The Fruit is edible. Intoxicating liquor can be made from it. This is a good tree to plant to attract birds. In order to obtain fruit, both male and female trees must be reasonably close together. The use of plant extracts in laboratory, as an anti-diarrhoea medication has been successful and more tests are to be carried out.
Boon, R. 2010. Pooley’s Trees of eastern South Africa. Flora and Fauna Publications Trust, Durban.
Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town.
Ginn, P.J. McIlleron, W.G. Milstein, S. 1989. The Complete Book of Southern African Birds. Struik Publishers (PTY) LTD. Third impression 1991.
Lawrence, G. H. M, 1951. Taxonomy of Vascular Plants, The Macmillan Company, New York. Tenth Printing 1965.
Palmer, E. & Pitman, N. 1972. Trees of southern Africa, Balkema, Amsterdam, Cape Town.
Schmidt, S. Lotter, M. & McCleland, W. 2002. Trees and Shrubs of Mpumalanga and the Kruger National Park.
van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa, Struik, Cape Town.