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..
Willow Family. Dioecious trees or shrubs with light wood, bitter bark, brittle twigs, alternate stipulate leaves, the stipules often minute and caducous. Flowers of both sexes in aments, solitary in the axil of each bract. Aments expanding before or with the leaves. Staminate aments often pendulous; staminate flowers consisting of from one to numerous stamens inserted on the receptacle, subtended by a glandlike or cup-shaped disk; filaments distinct or more or less united; anthers 2-celled, the sacs longitudinally dehiscent. Pistillate aments pendulous,erect or spreading, sometimes raceme-like; pistillate flowers of a sessile or short-stipitate 1-celled ovary subtended by a minute disk; placentae 2-4, parietal; ovules usually numerous, anatropous; style short, slender, or almost wanting; stigmas 2, simple or 2-4-cleft. Fruit an ovoid, oblong or conic 2-4-valved capsule. Seeds small or minute, provided with a dense coma of long, mostly white, silky hairs. Endosperm none.
The family includes only the 2 following genera, consisting of 200 or more species, mostly natives of the north temperate and arctic zones.
Bracts fimbriate or incised; stamens numerous; stigmas elongated.
Bracts entire; stamens 2-10; stigmas short.