ELYMUS CALDERI - A NEW SPECIES IN THE TRITICEAE (POACEAE)

Herbarium specimens identified as Agropyron yukonense or one of its sy nonyms consistently differ from the holotype and protologue of that na me and resemble each other in their stiff, involute leaves, narrow, da rk cauline nodal bands, and pilose paleas. This suggests that the non- holotype plants represent a new species. Cytogenetic analysis of root tip chromosomes from non-holotype plants revealed that they were tetra ploids with 2n = 28. Analysis of genome-specific DNA suggested that it contained the St and H genomes, resembling Elymus s. str. in this reg ard, rather than the morphologically similar genus Roegneria which con tains the St and Y genomes. Presence of the H genome and absence of th e Y genome were supported by analysis of 70 low copy DNA sequences det ected using sequence-tagged-site PCR analysis. Thus, morphological, cy togenetic, and molecular results support inclusion of the new species in Elymus. The name Elymus calderi is proposed, in honor of J.A. Calde r, a taxonomist who worked extensively in western Canada. A descriptio n, illustration, and distribution map are presented.