This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", 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..
Trees or shrubs, with alternate petioled simple leaves, and perfect, polygamous monoecious flowers, variously clustered. Perianth often imperfect. Calyx-tube, when present, more or less adnate to the ovary, its limb truncate or 4- or 5-lobed. Petals, when present, 4 or 5, perigynous. Stamens 4-00, perigynous; filaments distinct. Disk circular or none. Overy compound, of 2 carpels united below, 2-celled; styles 2, subulate, erect or recurved; ovules 1, suspended. Fruit a 2-celled 2-beaked woody or coriaceous capsule, dehiscent at the summit. Seeds 1 in each cavity, anatropous; embryo large; endosperm scanty.
About 13 genera and 40 species, natives of North America, Asia and South Africa.
Flowers white, in catkin-like spikes; petals none.
Flowers yellow, in axillary clusters; petals long.