Yellow-bark Acacia (Acacia erubescens) Fabaceae

•LUISE HOFFMANNTHE distinctive feature of the yellow-bark acacia during the period September to December is the pink colour of its numerous flower spikes, which appear before the foliage. However, some shrubs have cream-coloured flowers.

It is even said that the same tree may produce pink flowers in one year and cream flowers in the next season. Other characteristics to look out for are the papery yellowish bark peeling lengthwise off the stem and the very pale grey to white bark of the young twigs. The sharp, recurved, dark thorns grow in pairs. On the fairly long leaf stalk of most leaves there is a columnar gland protruding like a tiny stick.

Names: G Birkenrindenakazie; A blouhaak, withaak, berkebasakasia; H omungongomui; Nd omunkono; Ky okadilanghono; N/D!uri !gonis

The yellow-bark acacia occurs on rocky ground from the Auas Mountains northwards into the Karstveld, Etosha and up to the Kunene River, usually as a many-stemmed shrub of about 3 m or a tree up to 8 m high. It is also found along the Kavango River and in western Caprivi where these trees grow much taller and more luxuriant than further south. Mature yellow-bark acacias can be seen in the National Botanical Garden in Windhoek.

The bark on old trunks is pale yellow with patches of dark rough bark. On younger twigs it is almost white – a fact to which the Afrikaans name “withaak” or ‘white hook’ refers – and very obvious when the tree is bare. The fairly open feathery leaves are carried on a leafstalk of 13 mm – 25 mm. The very sharp, hooked thorns may reach a length of 7mm.

The flowers are arranged in fairly squat, short spikes and may be cream-coloured or various shades of pink. On some trees they are a much darker pink than on others. This acacia is the only common acacia in Namibia that can have pink flowers. [However, pink flowers are occasionally found on some black-thorn acacias (Acacia mellifera subsp. detinens)]. The scientific name erubescens means ‘blushing’ and may refer to this colour. The pale brown to dark brown papery pods are straight, taper towards both ends and split open when mature.

Uses: Rhinos and elephants eat the twigs while the leaves and pods are browsed by game and livestock. The wood provides good firewood. In Kaokoland it is also used to make walking and carrying sticks and the thorny branches are very suitable for constructing cattle enclosures and garden fences.

Of all Namibian acacias the yellow-bark acacia provides the sweetest edible gum. Most acacias produce gum to ward off harmful fungi and other micro-organisms, while corkwood trees and conifers produce resins for the same purpose. An easily observable difference between the two is that gum dissolves in water, while resin does not.

Due to its very attractive open feathery foliage, the pale yellow trunk and the profuse flowering in spring the yellow-bark acacia is well suited to indigenous gardens. Seedlings are available from the nursery of the National Botanical Research Institute, Contact No 061 202 2014.