Crack Willow – Salix fragilis
Crack willow is a fast-growing tree common along streams and swamps. This tree does not weep. The common name derives from the twigs which break off very easily and cleanly at the base with an audible crack. The broken twigs and branches take root readily, enabling the species to colonize new areas when they fall into the water and are carried away from the parent.
Native to Europe and western Asia, S. fragilis has escaped cultivation and become invasive in New Zealand. Care should be taken not to locate crack willows near underground water or sewer lines or close to septic tank drain fields where the roots could cause significant damage. Roots are aggressive and will spread about three times the distance from the trunk to the edge of the canopy and often grow on the soil surface.
Willow bark was steeped as tea by native Americans, and the young twigs and bark chewed to relieve headaches. It was later found the active ingredient was salicylic acid, the basis of today’s aspirin. The chemical name for aspirin comes from the willow family name, Salicaceae.
There are only two genera in this family, Salix (willows), with about 300 species, and Populus (poplars), with barely 40 species. Salicaceae are found throughout the temperate parts of the world, with the majority of species occurring in the north; both willows and poplars have a strong affinity for water.
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