Studies of population variability leading to a new classification of Potentilla sect. Multijugae (Rosaceae)

Abstract

This study had two goals: to produce a classification of a section of the difficult genus Potentilla; and to show how population variation affects this taxonomic classification. This genus is lacking a monograph which expresses natural relationships, or one which allows accurate identification, especially for North America. A new classification was made of Potentilla sect. Multijugae, a section of eleven species inhabiting western North America. In order to define this section, a new classification was also made of two related sections, Concinnae and Subjugae. Field studies on the species of these sections in the Rocky Mountains and Great Basin from New Mexico to Idaho and Montana yielded many population samples. Analysis of these population samples greatly improved the interpretation of approximately 7000 herbarium specimens representing these sections. Statistical analysis of variance and correlation of the population samples, character analysis (program CHARANAL), and single-linkage clustering (program GRAPH) provided objective methods of selection, structuring, and use of characters for classification.