This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Evergreen or deciduous shrubs often of trailing habit. Leaves opposite or rarely alternate, trifoliolate, pinnate or reduced to a single leaflet articulated with the petiole. Flowers often highly odoriferous, yellow or white. Calyx inferior, 5-to 8-lobed; lobes twisted or valvate in aestivation. Stamens 2, inserted upon and included within the tube of the corolla. Fruit a bilobate 2-celled berry or capsule; cells 1- or few-seeded. There are about 6 genera and 100 species, widely dispersed throughout the world except North America, but especially abundant in Asia.