|
Acacia sieberana DC. |
 |
Leguminosae
White thorn. |
Author: Le Houérou
|
|
Tree reaching 15-25 m in height and 60 cm in diameter, large, hemispherical to umbrella-shaped canopy, with strongly fissured bark, yellow to cream-colored in young trees and twigs, scaly in old trees, slash red. Thorns are white, strong and straight, in axillary pairs up to 6-10 cm long, but they may be short or absent altogether. Twigs with whitish lenticels. Leaves are bipinnate, with a rachis 6-15 cm long, with 10-25 pairs of pinnulae having 15-50 pairs of leaflets each. Leaflets 0.2-0.7 x 0.05-0.15 cm, glabrous or pubescent. Flowers are fragrant, cream-colored or light yellow in globose heads ca 1.5 cm in diameter., on peduncles gouped by 3-6 at the axils. Blossoming and foliation occur towards the end of the dry season before the onset of the rains (precession of foliation). Pods more or less falcate, woody and glabrous, brown to reddish-brown, varnished and shining when mature, 10 to 20 cm long, 2 to 2.5 cm broad, up to 1.5 cm thick, indehiscent, containing 12-15 large, brown seeds arranged in one row and embedded in yellow-green, spongy tissue. Flowering begins in November in the Transvaal, and the pods mature in August-September (West, 1950). Rainfall belts from 400 to 1200 mm MAR, tends to replace A. nilotica toward the southern limit of the latter, in the South Sudanian ecozone, above 800 mm MAR. Found on deep, well watered, but well drained, loam to clay soils. Widely, in mixed woodland in Africa from the central Sudan to the southern Sudan, all of Central and Southern Sahel, Kenya, Zambia, Zimbabwe, Angola, Botswana and the Transvaal. The subspecies are three: var. sieberiana, var. vermoesenii, and var. woodii. Bears heavy crops of edible pods which drop during the dry season. The branches are armed with numerous white thorns, making browsing hazardous. Limited numbers of trees could be retained to advantage in pasture. Encroachment should, however, be prevented as serious damage can be caused to the pasture. Eradication is a laborious and expensive process (van Rensburg, 1968). Dougall and Bogdan (1958) state that the pods are liked by rhinoceros and elephants, and Lamprey (1967) found seedlings of both Acacia albida and A . sieberiana, the pods of which are indehiscent, growing in elephant dung in the Lake Manyarra Game Reserve in Tanzania. The wood is moderately hard but resitant to termites, if not to other insects, it is easy to work and used for making tools, handles, mortars etc. Also used as fuel and for making charcoal, branches are used for dead fences ("zeribas" = "bomas"), occasionally planted as hedge or windbreak and as shade (palaver-tree) in villages, like Tamarindus indica. The nutritious pods, produced in abundance at the end of the rainy season are consumed by stock, particularly sheep and wildlife, particularly elephants ; they are sometimes collected for fattening pet animals in the Rep. of Sudan. The flowers are attractive to bees and hives are sometimes placed in the trees. The widespread branches of the tree give a lot of shade. The gum is of a fair quality, sometimes used to make ink. The bark is used as cordage fiber and for tanning, and the pods too. Local medicine usages are, vermifuge, to treat bilharziosis, haemorrhage, orchitis, diarrhoea, gonorrhaea, cold, kidney disorders, syphilis, circulatory disorders, rheumastism etc. Nutritional Quality and Animal Production The pods are readily eaten and contain 8.3 percent crude protein. The seeds contain 27.4 percent crude protein, and the tips of the young shoots, also eaten toward the end of the dry season, contain 21.13 percent.
Aubréville 1950 ; Berhaut 1975 ; Dale & Greenway 1961 ; Dalziel 1955 ; Geerling 1982/88 ; Giffard 1974a ; Karharo & Adam 1974 ; Weber et al. 1977 ; Von Maydell 1983/86 ; Burkill 1995 ; Wickens et al. 1995 ; Vassal 1998 ; Dommergues et al. 1999. |
