A MORPHOMETRIC ANALYSIS OF VARIATION BETWEEN ELYMUS ALASKANUS AND ELYMUS VIOLACEUS (POACEAE): IMPLICATIONS FOR RECOGNITION OF TAXA

摘要

The aim of this study was to clarify the relationships between Elymus alaskanus and E. violaceus in northwest North America. We performed a morphological and biogeographic analyses of ca. 300 widely distributed herbarium specimens. Following a univariate analysis of morphological characters used in contemporary treatments, we found no clear character, or combination of characters, that differentiates unambiguously among the taxa at the specific level. However, glume and lemma trichome length reliably separated E. alaskanus subsp. hyperarcticus from other taxa. Specimens could not be differentiated at the specific level by habitat preferences or geographic distribution as described in the most current treatments. Further, principal components analysis and cluster analysis were unable to reliably segregate specimens into groups. Discriminant analysis reliably grouped E. violaceus and E. alaskanus subsp. hyperarcticus, but not E. alaskanus specimens. In the development of a relevant treatment for E. alaskanus and E. violaceus, we recommend that (i) E. violaceus be treated as a subspecies of E. alaskanus and called E. alaskanus subsp. latiglumis, and (ii) E. alaskanus subsp. alaskanus and E. alaskanus subsp. hyperarcticus continue to be recognized at the subspecific level.