Oncoba spinosa

Oncoba spinosa, commonly the snuff-box tree or fried-egg flower and in Afrikaans the snuifkalbassie (little snuff calabash), is a spiny, single or multi-stemmed shrub or small tree typically reaching heights around 4 m, occasionally 8 m (SA Tree List No. 492).

The smooth, mottled bark is grey to pale brown. A main stem may reach 60 cm in diameter. Young branches are red-brown with many scattered, whitish lenticels along the surfaces. There are also straight, slender, sharp axillary spines of up to 5 cm long.

The leaves are simple, spiralling up the stems or alternate on stalks up to 1 cm long, grooved on top. The leaf-shape is ovate to elliptic with a tapering tip or attenuating drip-tip and a rounded to tapering base. The margins are coarsely toothed to scalloped, sometimes obscurely. The dark green, glossy blades are leathery to thinly textured, paler below and hairless, folded in along the midribs.

The greenish-white midrib is ridged on both surfaces. Four to eight pairs of lateral veins ascend and curve into the next vein, before the margin that is never reached. The veins and net-veining are visible above and below. Leaf dimensions are typically 7 cm by 3,5 cm, sometimes considerably larger. New leaves are coppery pink.

The sweetly scented flowers grow solitary at stem-tips and from leaf axils. The calyx consists of three or four sepals, joined at the base or free. There are up to twenty spreading petals, broad, white and overlapping with rounded tips. The flower centre has a bulging mass of tiny, golden stamens and a one-chambered ovary out of sight below. The flower diameter is about 9 cm. Flowering happens in spring to after midsummer.

The spherical fruit that follows around mid-autumn to well into winter is hard, dark red-brown and faintly, longitudinally ridged. It becomes up to 6 cm in diameter. Both the style and the reflexed calyx persist upon the fruit that does not burst open when ripe. The small, shiny brown or yellowish seeds are embedded in a yellow, sour and dry pulp seldom eaten.

The species distribution is only in the far northeast of South Africa, in KwaZulu-Natal, Mpumalanga and Limpopo, as well as elsewhere in Africa. This subspecies is the only Oncoba growing in South Africa. The generic name is derived from the plant’s Arabic name, oncob, giving an idea of the distribution range. The spinosa name is derived from the spines.

The tree grows in open woodland or bushveld among rocks, along drainage lines and streambank fringe forests, sometimes forming thickets. It is not considered to be threatened in its habitat early in the twenty first century.

The tree features in traditional medicine and in (too few) frost-free gardens. The light brown wood is hard, sometimes used. The dry fruit shells are used as rattles for children and dancers, as snuff boxes and earlier as penis covers (Coates Palgrave, 2002; Pooley, 1993; iNaturalist; http://redlist.sanbi.org).