Salix babylonica a gold-yellow in autumn. The flowers are arranged in catkins produced early in the spring; it is dioecious, with the male and female catkins on separate trees. "Salix babylonica" was described and named scientifically by Carolus Linnaeus in 1736, who knew the species as the pendulous-branched ("weeping") variant then recently introduced into the Clifford garden in Hartekamp in The Netherlands. Early Chinese cultivar selections include the original weeping willow, "Salix babylonica" 'Pendula', in which the branches and twigs are strongly pendulous, which was presumably spread along ancient trade routes. These distinctive trees were subsequently introduced into England from Aleppo in
Salix brachycarpa The plant produces tiny, downy seeds which are viable for just a few days but may germinate within 12 hours of hitting a suitable substrate. There are at least two recognized varieties of this species of willow: A former subspecies, "Salix brachycarpa" subsp. "niphoclada", is now synonymous with "Salix niphoclada", another Alaskan willow species that is also commonly referred to as barren-ground willow. Of note, barren-ground willow is also the common name of a third but distinct species of willow found in Alaska, "Salix nummularia". On the Alaska North Slope, sites that supported this and other low-growing willow species before