This spiny shrub or small tree with pretty white flowers is known for the snuff boxes that can be made from its hard-shelled fruit.
The snuff-box tree grows up to 5 m, but may sometimes reach a height of 8 m. The bark of this plant is mottled grey and rather smooth. The young branches are conspicuously speckled with lenticels (a slightly raised, lens-shaped area on the surface of the young stems that helps with the exchange of gasses between the plant and the surrounding air). The spines are straight and up to 50 mm in length.
The leaves are simple, ovate-elliptic in form with a somewhat pointed tip and rounded, broad base. The leaves are dark, glossy green in colour and somewhat leathery and hairless. The margins are coarsely toothed.
It bears large (90 mm wide) showy, sweet-scented, white flowers with masses of yellow, overlapping stamens in the centre . Flowers somewhat resemble a fried egg and in Zimbabwe it is called the fried-egg flower. The flowers are bisexual and are borne at in the base of the leaves or at the end of the branches. It flowers from September to January. The ovary is one-chambered.
The rounded fruit of up to 60 mm in diameter, consists of a hard shell that becomes dark-reddish brown when mature and small, with shiny brown seeds embedded in a dry, sour, yellowish pulp. Fruit can be found on the tree from April to July.
Distribution and Habitat
This tree occurs in the northeastern part of South Africa, primarily in Mpumalanga and further north along the Zambezi River. It is found over a large range of altitudes, from bushveld areas to riverine fringe forest.
Derivation of name and historical aspects
Oncoba is derived from the Arabic name for the North African species, Onkub ; spinosa , referring to the spines. Spines are usually a modification of a leaf or stipule, a small scale or leaf like appendage at the base of the leaf stalk.
Uses and cultural aspects
The pulp of the fruit is edible, but is seldom used for that purpose. In African medicine the roots are used in the treatment of dysentery and bladder complaints. The hard-shelled fruits are used as snuff boxes. If the fruit are left to dry with the seeds inside they it make amusing rattles for children and are also used as anklets and armlets for dancers to add rhythm when performing.
It is said that the seeds contain a drying oil that is suitable for varnish, but it is too difficult to extract to be of any commercial significance. The wood is light brown in colour and can take a good polish, but the pieces are seldom large enough to be of any commercial value.
Growing Oncoba spinosa
Cultivation is not difficult and fresh seeds, collected from the tree, can be pushed into river sand flush with the surface and kept moist. Initial growth is slow but will speed up after 9 to 12 months. It can grow up to 500 mm per year in the Highveld region and even up to 1 m in areas with a high rainfall. It is a protected tree in South Africa.