For the identification of insects and other fauna and flora of South Africa.

Friday, January 11, 2013

River Bushwillow (Combretum erythrophyllum)

Family  Combretaceae
One of the winged wonders belonging to the bushwillow family, this medium-sized tree is a fast grower, producing creamy flowers and beautiful 4-winged seeds of a greenish brown colour when young and drying to a honey-brown.


Description

This is a medium to large deciduous tree with reddish autumn colours. Flowers are cream to pale yellow (September - November). Fruit are small, 4-winged and a greenish brown colour, ripening to yellowish brown and drying to a honey-brown. They remain on the tree for a long time and are reputed to be poisonous, causing hiccups. The bark is a pale brown, smooth, but flaking with age to expose grey patches, which give it a mottled appearance. Knob-like outgrowths commonly occur in older trees, giving them an old, gnarled look. The young leaves are yellowish and shiny maturing to a fresh mid-green. Trees are often multi-stemmed and somewhat willow-like in habit.

Distribution

This species is found in the northeastern part of South Africa, from Zimbabwe in the north down to Eastern Cape in the south with a thin line following the Orange River westward. This is a riverine species, occurring alongside rivers or away from rivers where sufficient groundwater is available. It is found at almost all altitudes and can therefore tolerate a fair amount of climatic variation and diverse soils such as heavy black loam, sandy riverine alluvium and granite sand.

Ecology
Giraffe and elephant browse the tree. The seeds, although said to be generally poisonous, are eaten by Pied Barbets. Wasps sometimes lay their eggs through the fruit wall. The newly hatched larvae then feed on the seeds. Birds such as the Southern Black Tit tap each fruit, open those that contain grubs and eat them.

Uses and cultural aspects

The gum has interesting properties. It is non-toxic, elastic, producing a non-cracking varnish. The roots, which some regard as poisonous, are used as a purgative and to treat venereal diseases. Ornaments, cattle troughs and grain mortars are made from the wood. A dark, rich brown dye is extracted from the roots. The dried fruits also work well in flower arrangements.