Buckthorn

Buckthorn, common name for a family comprising about 875 species, in 53 genera, of mostly trees and shrubs, although some are climbers. The family is cosmopolitan in distribution. Many species exhibit adaptations to dry habitats, including small, crowded leaves; thorns and spines; and short branches. In addition to ornamentals, the family is important as a source of some medicines (see Cascara Sagrada). It is also an important source of natural green and yellow dyes and fruits (from the lotus tree, or jujube). The common buckthorn, sometimes cultivated in shrub borders, has large spines; small, oval leaves; and small white flower clusters. Its blue-black, pea-size berries are cathartic.

The family belongs to an order that contains two other families. The distinctive feature of the order is the nature of the flowers, which always have as many stamens (male flower parts) as petals, usually four or five. Also, whereas in most plant groups the stamens are attached between the petals, in this order they are attached opposite the petals. Another distinctive feature of the flower is a disk of nectar-producing tissue located between the stamen and the pistil (female flower part).

One of the other families in the order contains about 13 genera and 700 species of mostly tropical and subtropical climbers with tendrils (modified shoots) that coil around objects, attaching the vines to them. This family is of tremendous importance because it contains the genus from which wine, grapes, and dried fruits are obtained. Virginia creeper, or American ivy, an attractive ornamental, is also a member of this family (see Ivy). The third family contains about 70 species, all placed in one genus.

Scientific classification: Buckthorns make up the family Rhamnaceae, of the order Rhamnales. The common buckthorn is classified as Rhamnus cathartica. Two other families of the order are Vitaceae, containing the genera Vitis and Parthenocissus, and Leeaceae, containing the genus Leea.