Salix Fragilis and Salix Alba
The fragilis and alba group of genus Salix gives rise to puzzling questions of determination and nomenclature. Pure fragilis and pure alba are perfectly distinct plants, fragilis occasional, locally rather common, and alba rather rare within the limits of the United States. Each species has varieties; the two species hybridize with each other and with native species, and the hybrids themselves have varietal forms. This group affords a tempting field for the manufacture of species and varieties, about most of which so little is known that any attempt to assign a definite range would be necessarily imperfect and misleading. The range as given below in either species simply points out the limits within which any one of the various forms of that species appears to be spontaneous.