Periwinkle, the popular name of the gentis Vinca, two species of which, doubtfully indigenous, are the only British representatives of the considerable tropical drder of Gamopetala; (q.v.), Apocynacese. They are prostrate perennial evergreen herbs, with wiry stems; opposite, ovate, leathery leaves; and salver-shaped, blue, white, or redflowers, an inch or more across. There are five petals: the corolla-tube is hairy inside, and has five included epipetalous stamens; and there are two superior many-seeded carpels and a single style. There is a poisonous milky latex.