A TAXONOMIC RECONSIDERATION OF SALIX-TAXIFOLIA SENSU-LATO (SALICACEAE)

Salix taxifolia s.l., originally described as two species, has been treated as either a single species, or as two varieties: var. taxifolia and var. microphylla. Morphological, chemical, and phytogeographical evidence supports treating Salix taxifolia and S. microphylla as species. These taxa are distinguished on the basis of leaf length, leaf length-width ratio, the number of teeth or glands on the leaf margins, the presence or absence of abaxial nectaries in the staminate flowers, the presence or absence of foliar stipules, and by their flavonoid profiles. Their geographical ranges are different and come into contact only in the state of Durango, Mexico. Phenetically, all of the subgroups of S. taxifolia are more similar to each other than they are to S. microphylla. Both of these taxa are morphologically more similar to each other than they are to other members of sect. Longifoliae. A key to the species and descriptions are provides.