Frangula is a genus of about 56 species of flowering shrubs or small trees, commonly known as buckthorn, in the buckthorn family Rhamnaceae. The common name buckthorn is also used to describe species of the closely related genus Rhamnus in the same family, and also the superficially similar but only distantly related sea-buckthorn, Hippophae rhamnoides in the Elaeagnaceae.
Description
Frangula species are deciduous or evergreen shrubs or small trees (to 12 metres tall in F. purshiana) with dark grey-brown to blackish bark; alternate, simple leaves with stipules, buds without bud scales, branches without spines; and flowers with five small petals (cf. usually four in Rhamnus) and undivided styles. The fruit is a two- to four-seeded berry; it is dispersed by birds. but have increasingly been treated as a distinct genus in their own right.
The designated lectotype species is Frangula alnus Mill., based on Rhamnus frangula L.
The following species are accepted by the Plants of the World Online database (POWO):
As with Rhamnus species, the berries are a powerful purgative.