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.
Shrubs or herbs with opposite usually exstipulate simple or compound leaves and usually corymbose or cymose flowers. Calyx-limb superior, 3- to 5-toothed or -lobed. Corolla regular or irregular, often 2-lipped. Stamens 4 to 10, inserted upon the corolla. Fruit a berry, drupe, or dry capsule, indehiscent, 1- or more celled and seeded; seeds albuminous, often with a horny testa. There are about 200 species, in 14 genera, chiefly from the temperate parts of the northern hemisphere.