Phenetic similarity patterns of dioecious species of Poa from Argentina and neighboring countries

Dioecious species of Poa L. are mainly American with a total of 41 taxa in South America, 11 in North America, 2 in New Zealand, and 1 species in the Peri-Antarctic Islands. South American species, considered within Poa sect. Dioicopoa, are found mostly in Argentina but occur elsewhere in Bolivia, B razil, Chile, Paraguay, and Uruguay. The present treatment considers the ph enetic variation of dioecious species of Poa in South America. Thirty-seven taxa (34 species and three varieties) were examined, using numerical techn iques. Multivariate analyses revealed a phenetic pattern among species base d on linear relationships. Relationships of independent species as well as species complexes were established. As a consequence, new synonymy within m ost of these complexes, and a new variety, Poa rigidifolia var. ibari, are proposed herein. Bivariate analyses showed other non-linear patterns of var iation. These results, together with univariate analyses, were used to sele ct diagnostic characters. Sexual dimorphism was the major source of species variation, and ranges for pistillate and staminate specimens were also cal culated. An identification key for all taxa is included.