Bailey, L.H. (1949) Manual of Cultivated Plants Revised edition. Macmillan, New York.
Description of the genus
Shrubs or small trees. Calyx 5-toothed, enlarging and enclosing the fruit. Corolla long-tubular with short lobes. Anther not connivent around the style. Fruit a berry.
Derivation of name: From the Greek, meaning 'violet-coloured'