Evergreen shrubs or trees, of which about thirty species are known, inhabiting all three continents of the Old World, also the W. Indies and Central America. The leaves are opposite, not toothed or lobed, leathery in texture, easily separated into two layers. Flowers unisexual, small and inconspicuous, produced in short dense clusters in the leaf-axils in spring, the males and females in the same cluster, the former the more numerous. They have no petals; but the male has four sepals and four stamens, the female six sepals and three pistils. Fruit a three-celled capsule, each valve two-horned; seeds black and shining. Wood of hard, bony texture.
The boxes succeed in almost any soil, and are often found wild on a limestone formation. They are useful for semi-shaded positions. Cuttings of all the cultivated species and varieties except B. wallichiana strike root freely.