垂柳
A similar willow species also native 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.