Strychnos spinosa aka Kaffir Orange

Strychnos spinosa is a thorny shrub or small tree. It belongs to the Loganiaceae family. The RHS calls it Natal orange. Its native range spans tropical and southern Africa and the western Indian Ocean. In Africa, it grows from Senegal to Somalia and south to South Africa. It lives in dry woodland, thickets, and savannah. It also occurs in forest along rivers.

The plant sheds its leaves and forms a rounded crown. It often grows with more than one main stem. Its usual height is about 13–16 feet [4–5 metres]. Some trees reach about 33 feet [10 metres]. Wild plants often grow on sandy loam beside rivers. They occur at heights up to 7,218 feet [2,200 metres] above sea level. People often keep these trees when clearing land for crops.

Insects pollinate the flowers. The round fruit turns yellowish orange and has a hard, woody shell. Inside, many flat seeds sit within thick, jelly-like pulp. Ripe pulp has a sweet-sour taste. People eat it fresh, cook it, or dry it for later. They also ferment it to make an alcoholic drink. A bitter taste can develop if pulp stays in the mouth too long. Seeds and unripe fruit are toxic. The edible pulp must not be confused with these unsafe parts.

This tree suits hot, seasonally dry tropical and subtropical sites. It grows best in full sun but accepts some shade. It prefers sandy soil that drains well. It can also grow in poor, rocky ground. Slightly acid to neutral soil suits it best. Its preferred daytime range is 68–82°F [20–28°C]. It can endure an occasional light frost. The source describes overall growth as medium, though seedlings can grow quite fast. Growers can raise plants from seed, root suckers, or half-ripe cuttings.

People harvest wild fruit and also grow the tree as a crop. Cultivation includes West Africa, Madagascar, and southern Florida. The hard wood serves for furniture, tool handles, poles, and carving. It also supplies fuel and charcoal. Dried fruit shells serve as sound boxes for mbira instruments. People carve the shells into small craft items too. Traditional medicine uses several parts, but this does not establish safe treatment. Roots mixed with oil have also served as a fly repellent.