This taxon originates from southeastern Europe and the Caucasus region, but has been widely planted in North America (Argus 1986, FNA 7). Its origin as a hybrid from S. alba and S. euxina I. Belyaeva has been shown only in recent years, and the extent of further intergradation with alba remains uncertain. There has been much confusion among these taxa and others. In Ky. the extent of naturalization is not generally clear based on collection data. Typical fragilis differs from alba in its leaves, which are strictly glabrous (versus long-sericeous to glabescent below), less glaucous, coarsely and irregularly crenate-serrate (versus minutely serrulate), and generally larger (up to 10-14 x 1.7-3 cm versus 7-13 x 1.3-2.5 cm). Also, it has longer styles (ca. 0.6-0.8 mm versus 0.2 mm), and longer aments (5-6 cm versus 3-3.5 cm).