Boscia albitrunca, commonly known as the shepherd tree or shepherd's tree, is a protected species of South African tree in the caper family. It is known for having the deepest known root structure of any plant at: -68 m. The species epithet "albitrunca" refers to the white trunk it oftentimes develops. Traditionally, the shepherd tree was used by Dutch settlers, boers, to create a variant of coffee from the roots of the tree. It is an evergreen tree native to southern and tropical Africa, living in the hot, dry, and often seasonally brackish low-lying areas, sometimes on abundant lime or occasionally on rocky terrain. It is a common tree of the Kalahari, bushveld and lowveld. It is one of the most important animal forage trees in the Kalahari.

Description

This tree grows up to 10 m tall but is usually much smaller. It has a prominent, sturdy white trunk frequently with strips of rough, dark-coloured bark. The crown is often browsed by antelope and any grazers capable of reaching the foliage, resulting in a conspicuous flattened underside, or browse-line. The leaves are narrow, oblanceolate, and stiff, with veins obscure except for the distinct midrib. The flowers are small, greenish-yellow, lacking petals, starburst-shaped, and clustered. The fruits, on a jointed stalk, are about 10 mm in diameter and are brittle-skinned with a whitish flesh and large endocarp. A specimen found in the central Kalahari in 1974 had roots extending to 68 m deep, making it the plant with the deepest known roots thus far found.

Relationships

Boscia belongs to the caper family, Capparaceae. Boscia albitrunca is closely related to Boscia foetida subsp. rehmanniana, the bushveld shepherd's tree, which has much smaller leaves and velvet-textured skin on its fruits. The genus was named for Louis Bosc (1759–1828), a French professor of agriculture who lived through the French Revolution.

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