This Tree may reach 10m high. Stout Branches are crooked. Simple Leaves become hairless. Star-shaped, yellowish-green Flowers lack petals and have a central mass of yellow stamens. Fruit is a berry with 1 Seed.
Boscia albitrunca, Boscia pechuellii, Boscia transvaalensis, Capparis oleoides, Capparis punctate.
RSA Tree No. 122.
Common names: Shepherd(’s) tree, Grooy-witgat, Caper Bush, Coffee tree, Emigrant’s tree, Noenieboom, Witstam(boom), Witteboom.
Family: Capparaceae. (The caper family) has about 16-33 genera and 480-700 species. This family has trees, shrubs and some lianas (climbing plants that are woody and hang from trees). Members are tropical and sub-tropical. Flowers are usually 4-merous. The superior Ovary usually has 1 locule. Fruit is a capsule or a berry. Mustard Oils are present in all genera. Local genera include Boscia and Maerua.
Name derivation: Boscia – Louie Augustin Guillaume Bosc (1759-1828) was a French botanist, invertebrate zoologist and entomologist. He also wrote the first ever-systematic examination of the mushrooms of the southern USA. albitrunca – refers to the trunk which may be white. The Genus Boscia has 37 species. There are 9 species in southern Africa.
Conservation Status: L.C. (Least Concern). 2009 (Raimondo et al.). Due to its high regard in many local traditions, the tree is somewhat protected.
The often single stemmed Tree may reach 10m in height but usually smaller. However, it can also have a branched trunk or even be a low mat over rocks. The Stem (main axis of the plant, the leaf and flower bearing as distinguished from the root-bearing axis) is usually twisted and may be whitish with strips of darkly coloured bark. The stem may be pitted. Light coloured 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 branches. The Crown is compact and rounded in open spaces. Branches are stout, crooked and spineless. This tree has the deepest roots of any plant in the world. They reached a measured depth of 68m in the Kalahari in Botswana. Second is Acacia erioloba with a root depth of 60m.
The stiff, simple, entire and coriaceous (leathery) Leaves are alternate or fascicled (condensed cluster of leaves). They are evergreen but some leaves are lost when the flowers appear. Leaves are usually slightly oblanceolate (leaf broader at the apical third than at the middle and tapering towards the base) or elliptic. They are often Bristle-tipped (photo 942) and may reach 8 x 2,5cm. Mature leaves are hairless. Leaves have a distinct Midrib. The upper surface of the blade may be shiny and darker than the lower surface. Other veins are obscure unless the leaf viewed against a strong light (photo 929). The Petiole (leaf stalk) is short and thin. Herbivorous animals account for the often-visible grazing line at the crown base.
The star-shaped, bisexual and strongly scented Flowers manly develop in axillary clusters or on short spur branches. Pedicels (stalks of single flowers) are absent. The 4 fleshy Sepals are free, yellowish green, valvate (meeting by the edge without overlapping) and lanceolate. Petals are absent. The central 5-15 yellow Stamens all have free Filaments. Anthers have 2 Theca (pollen sacs) which open by longitudinal slits. There is a single Pistil (a unit of the gynoecium, composed of the stigma, style and ovary) resting on a Gynophore (a stalk present in some flowers that supports and may elevate the gynoecium) which is up to 8 mm long. The ovoid 1-locular superior Ovary with 10 ovules, has a single Style with a capitate (formed like a head) Stigma. Flowers often occur in profusion after spring rains. Trees do not flower every year. (Jul-Nov but usually Sep-Oct).
When ripe the hairless, yellowish or light brown Fruit is up to 1,2cm wide. It is an almost spherical Berry (pulpy, indehiscent fruit like a grape or tomato). Each berry has a clusters of stone cells in the brittle exocarp (skin; the outer layer of the pericarp of a fruit). The middle layer or mesocarp is the juicy part and has a whitish flesh. The endocarp (the inner layer of the pericarp or fruit wall) is large. Berries lack ribs. The mature fruit has a brittle skin. The single Seeds that are usually produced lack endosperm (the starch and oil-containing tissue of many seeds – often referred to as the albumen). (Nov-Mar).
Distribution & Ecology
This is a protected tree in the RSA. It is located in Northern Cape, KwaZulu-Natal, Free State, Gauteng, Limpopo, Mpumalanga and North West. It is also found in Swaziland, Botswana, southern Mozambique, Zimbabwe, Zambia, Namibia and into tropical Africa. Because it is able to survive in very dry places, it is common on the red sands of the Kalahari Desert. Trees occur in hot dry areas including bushveld, open woodland and are associated with termite mounds. Leaves have a high vitamin A level and a high (14%) protein content. Leaves are sought after and consumed by all the herbivores that can reach it. Elephants eat the Bark. Both birds and animals – including kudu, giraffe and gemsbok, consume the Fruit. Flowers are eaten by antelope and attract masses of insects. Butterflies, whose larvae consume the Leaves, include the Browned White (Beleonis aurota) which is common in Africa and India, and the African Common White or African Caper (Belenois creona).
In very dry areas, this may be the only tree that provides both shade and valuable grazing for stock. Caper (seasoning or garnish) substitutes can be formed by pickling flower buds in vinegar. Local people also eat the acrid Fruit. Roots have been used for making coffee (apparently not very good) and porridge. A syrup made from boiled roots is reputed to be good. Propagation is by seeds or cuttings; however, seeds germination is unpredictable. Healers use parts of the tree. Milk from cows that eat the leaves may be tainted. Wood is heavy, tough and is suitably for making household implements.
Boon, R. 2010. Pooley’s Trees of eastern South Africa. Flora and Fauna Publications Trust, Durban.
Burrows, J.E., Burrows, S.M., Lotter, M.C. & Schmidt, E. 2018. Trees and Shrubs Mozambique. Publishing Print Matters (Pty) Ltd. Noordhoek, Cape Town.
Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town.
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.