Poa secunda Presl versus P. sandbergii Vasey (Poaceae)

Abstract

Populations making up the Poa secunda complex of South America are morphologically within the range of variation displayed by the group of western North American poas having only slightly compressed to rounded lemmas, all of the latter transitional to and possibly conspecific with Poa sandbergii Vasey. Moreover, the South American populations occupy areas with climates analogous to those in which the North American populations occur. Poa secunda Presl, therefore, is con- sidered to be the correct name for the North American species and Poa sandbergii Vasey is reduced to synonymy. Confusion surrounding the relationship between Poa secunda of South America and P. sandbergii of North America evidently derives from in- sufficient information about South American populations of this distinc- tive element of Poa. Because there has been no clear understanding of the relationship involved, North American populations are currently re- ferred to P. secunda by some workers and to P. sandbergii by others. A detailed morphological comparison of the disjunct North and South American populations is herein provided, and distribution patterns are discussed in terms of climatological extremes. The nature of the rela- tionship among the various taxa into which the North American popu- lation is generally divided is currently under investigation by Elizabeth Coombs of Harvard University (pers. comm. 1981). In this paper, my