A taxonomic study of the large-glumed species of Stipa (Gramineae) occurring in Canada
The morphology and awn anatomy of the large-glumed species of Stipa occurring in Canada were examined. Numerical analysis of the data indicates that S. spartea var. spartea and S. spartea var. curtiseta are very distinct taxa differing not only in many of their quantitative characters but also in nodal pubescence, ligule shape, and pubescence of the leaf margin. It is proposed that they be treated as separate species, S. spartea and S. curtiseta. Some evidence was found for differentiation within S. spartea s.s. but it was deemed insufficient for the recognition of infraspecific taxa. Stipa comata var. comata and S. comata var. intermedia are very similar in all morphological characters examined. Cross sections of their distal awn segments do, however, show consistent distinguishing characters; those of var. intermedia are more heavily lignified and tend to be square in outline compared with those of var. comata. Although similar to each other, cross sections of the varieties of S. comata are distinct from those of S. spartea and S. curtiseta. The possibility that certain specimens were hybrids between S. comata var. comata and S. curtiseta was explored and rejected. Distribution maps and a key to the accepted taxa are given.