This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Herbs or shrubs (some exotic genera trees), with alternate or opposite entire exstipulate leaves. Flowers clustered or solitary, axillary or terminal, perfect, monoecious or dioecious, mostly greenish. Calyx adnate to the base of the ovary, or to the disk, 3-6-lobed, the lobes valvate. Petals none. Stamens as many as the calyx-lobes and inserted near their bases, or opposite them upon the lobed or annular disk; filaments slender or short. Ovary 1-celled; ovules 2-4, pendulous from the summit of the central placenta; style cylindric, conic or sometimes none; stigma capitate. Fruit a drupe or nut. Seed 1, ovoid or globose. Testa none; endosperm copious, fleshy; embryo small, apical.
About 26 genera and 250 species, mostly of tropical distribution, a few in the temperate zones.
Perennial herbs; flowers perfect, cymose or solitary.
Shrubs; flowers imperfect, mostly dioecious.
Leaves alternate; flowers racemose.
Leaves opposite; flowers umbellate or solitary.