Koeleria macrantha and K. pyramidata (Poaceae): Nomenclatural Problems and Biological Distinctions

Abstract

Uncertainty concerning the correct name for the only species of Koeleria widely distributed in the northern hemisphere is heightened by the recent introduction into American literature of the name K. pyramidata. Population samples of European K. pyramidata were compared with population samples and herbarium specimens of North American material here referred to K. macrantha. Nineteen characters were evaluated for plants from each of seven populations of K. pyramidata and from each of five populations and 96 herbarium specimens of North American K. macrantha. Morphologically, K. pyramidata differs from K. macrantha in having larger spikelets (plants among the North American population samples of K. macrantha bearing atypically large spikelets were infected with Claviceps purpurea); a distinctive pattern of pubescence; a difference in response of sheath bases to weathering; and, in terms of populations, a more robust habit. The two species are also distinct cytologically, geographically, and ecologically. No evidence was found to suggest that plants with the morphological or cytological characters of K. pyramidata exist in North America. In view of these findings, K. pyramidata is deemed to be a distinct species, and the correct name for all North American material is K. macrantha. The lack of consensus as to the correct name for the grass until recently known in most of North America as Koeleria cristata (L.) Pers. is well illustrated by the application to that spe- cies of five different epithets by contemporary authors: K. gracilis Pers. (Looman 1978); K. cris- tata (L.) Pers. (Scoggan 1978; Tzvelev 1984); K. nitida Nutt. (Holmgren and Holmgren 1977; Welsh 1974); K. macrantha (Ledeb.) Schultes