B. Michelle Smith, Ecology 350 

Family Salicaceae


Description: Common characteristics of the willows include: lateral twigs from younger trees tend to snap off easily, soft, lightweight wood, bitter bark, sizes ranging from shrub to tree, alternate leaves, male and female on separate plants, fruit contains seeds with cottony hairs, narrow leaves (Knopf, 1980. )

 Species in the genus Salix

 Note: This list is considered complete by Christopher Newsholme (see references). Different sources listed different numbers of species, ranging from 350 up to 500. Where possible, the common name in included along with the Latin name.


Identification Guide: Willows are often considered very difficult to distinguish from each other. Because they often hybridize, the problem is compounded (Duncan & Duncan, 1988). Listed in the following identification guide are the willows of the southeastern United States with descriptions quoted from The National Audobon Society Fieldguide to North American Trees and Salix in the Southeast. For further identification, see these sources. The seeds are kept in catkins, which are basically long, scaly cones. The reason they are called catkins is because the seeds that they contain have tufts of hair which appear fuzzy (also hence the name pussywillow).

This identification key includes direct quotes on identification from the previous listed sources plus simple characteristics that may help someone without a field guide identify some of the better known species. (from Gray's Manual of Botany 1950).




General Information: All member of the genus Salix are dioecious , male and female are on separate trees (Massey, 1944). They occur on all continents except Australia, and are most common in the Northern Hemisphere (Everett, 1983). The bark is soft and lightweight and is often used in making plywood, veneer and matchsticks (Duncan & Duncan, 1988). Other uses have included making aspirin, (hence salic acid) and Eskimo kayaks (Everett, 1983). They are commonly eaten by mammals, including deer and rodents (Massey, 1944) and produce a favorite pollen of bees (Duncan & Duncan, 1988).

Sizes of the members of the genus range from small shrubs and bushes to large trees. The largest native tree of the United States is S. nigra. Most tree-sized species (other than S. babylonia) are not used in cultivation because their long, thick roots tend to spread out and interfere with walkways, streets, and irrigation or sewer systems (Newsholme, 1992).


Species Researched: 

S. babylonia - Weeping willow

S. nigra - Black willow


References Cited: