Tree up to 15m high. Simple Leaves – margin entire. 4-merous, small Flowers are in spikes with 8 stamens. Fruit: a 4-winged samara with 1 Seed. Largest leaves and fruit in the genus Combretum.
Combretum zeyheri, Combretum bragae, Combretum oblongum.
RSA Tree No. 546.
Common names: Bushwillow, Zeyher’s Bushwillow, Large-fruited Bushwillow, Large-leafed Bushwillow, Raasboom – referring to the noise of the dry leaves or fruit in the wind.
Family: Combretaceae (Bushwlillow family). In this family, there are about 16 genera, which contain about 530 species. In the RSA, there are 5 genera and 41 species. The RSA genera with trees are Combretum, Lumnitzera, Pteleopsis and Terminalia. The simple and usually entire Leaves lack stipules. Flowers are usually bisexual. There are usually twice the number of stamens as sepals or petals. The inferior Ovary has 1 locule and usually only 1 of the ovules develops into a seed. Fruit is usually indehiscent and may be winged or ridged.
Name derivation: Combretum – a climbing plant named by Pliny (AD 61-113). zeyheri – the first collector was Carl Ludwig Zeyher (1799-1858) in Magaliesberg in 1835. He put together a descriptive account of some South African plants.
Conservation Status: L C. (Least Concern). 2009 (Raimondo et al).
Description. The graceful, spreading and erect Tree has a rounded crown. The plant may also be multi-stemmed. It may reach up to 15m high but is usually less than this. The Trunk may have a diameter of up to 38cm and it may be twisted. The drooping Branches tend to be slender and are situated low down on the trunk. They may be reddish. Young Stems are hairy and have a fairly smooth and the whitish Bark. This becomes rough and mottled with age. When pieces of the bark are shed, the red underbark may become visible.
The simple (have a single blade, which may have incisions that are not deep enough to divide the blade into leaflets) Leaves are, usually opposite but may appear in whorls of 3 on young branches. They are clustered towards the ends of branches. The Leaves are elliptic, oblong or obovate. Most of the Hair present on young leaves is lost and adult leaves are almost hairless and leathery. The leaves are up to 14 x 9cm, which are the biggest of the indigenous Combretum genus. They may have a yellow tinge. In Autumn, the leaves turn a clear brilliant yellow and may remain on the tree until emergence of flowers. The Midrib and the 7-10 pairs of lateral veins and net veining are visible but are not deeply sunken above. Below, the midrib and lateral veins protrude and are clearly visible. Hairy Domatia (a tiny chamber produced by plants that house arthropods. To the naked eye the domatia appear as small bumps) are visible in the vein axils. These are visible if you carefully observe the upper leaf in photo 95. Scales are present on the underside but are not visible to the naked eye. The bluntly pointed, rounded, flat or notched Apex It may bend slightly upwards and the Base is either narrowed or rounded. The entire (with a continuous margin, not in any way indented but may be hairy) Margin may be wavy. The hairy Petiole (leaf stalk) has a swollen base and is up to 1cm long.
The small Flowers are densely arranged ingroups of round axillary Spikes (simple indeterminate inflorescence with sessile flowers on a single unbranched stalk) that are up to 8cm long. Flowers usually appear before or with the new leaves. They may be unpleasantly scented. Each bisexual flower is white to cream coloured with a red centre. Individual flowers have 4 Sepals in the Calyx and there 4 small Petals in the Corolla. The 8 initially orange Anthers are dorsifixed and versatile (hung or attached near the middle, and usually moving freely). There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma). This contains an inferior Ovary with a slender Style. (Sep-Nov).
The large, stiff, shiny wings of the Fruit are initially green and turn light golden brown. The fruit is a samara (a dry, indehiscent winged fruit. The wings are papery and develop from the ovary wall). This fruit is the Largest of the indigenous members of the Combretum genus – reaching 5 to 10cm and is diagnostic. Each fruit contains a single Seed. Although they are individually of low density for dispersal, they occur in such large numbers that cause the branches to bend. The fruit makes a rustling noise in the wind, which is easy to hear – especially in winter when the leaves have fallen. (Dec-Oct).
Distribution & Ecology
Provincial: Trees occur naturally in KwaZulu-Natal, Mpumalanga, Limpopo, Gauteng and North West. They also occur in Swaziland, Botswana, Zimbabwe, Namibia and northwards. They grow in poor, sandy soils like sand dunes, soils with a low pH (acidic) on stony hill slopes and at medium to low altitudes in summer rainfall areas. The tree is drought resistant. It often grows with Combretum molle, Burkea africana and Vachellia robusta. The Flowers attract bees. Giraffe, relish the Leaves. Hornbills break the fruit and eat the Seed. Butterfly larvae of the Apricot Playboy Deudorix dinochares feed on this Fruit and that of Acacia, Gardenia and many others. The male wings are largely orange and the female wings are a greeny yellow.
The Wood is yellowish-white and, like Celtis africana, it can have an unpleasant smell when cut. It may be prone to borer attack. When dry, the wood works well and is a good all-round timber, which is durable if thoroughly seasoned. Roots that are close to the surface are used for making initiation necklaces for girls. They are also used for making baskets. The roots are normally beige and are sometimes dyed grey or dark by using bark from Pterocarpus angolensis (kiaat) or from Burkea africana. In Namibia, fishing traps are made from the roots. Gum is edible and has some antibiotic properties. Burned Bark ash solution is used for straightening hair. Leaf extracts have an anti-fungal component. The fresh Seeds will grow after soaking overnight. The plant is initially frost sensitive and grows best in full sun.
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.
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.