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 babylonica to northern China, "Salix matsudana" (Chinese willow), is now included in "Salix babylonica" as a synonym by many botanists, including the Russian willow expert Alexey Skvortsov. The only reported difference between the two species is "S. matsudana" has two nectaries in each female flower, whereas "S. babylonica" has only one; however, this character is variable in many willows (for example, crack willow "[Salix fragilis]" can have either one or two), so even this difference may not be taxonomically significant. "S. babylonica," especially its pendulous-branched ("weeping") form, has been introduced into many other areas, including Europe and the southeastern United States,