Materials and Methods

Our study is based on examination of specimens by Torres in BAA, BA, BAB, CORD, CTES, LIL, LP, MERL, P, SGO, SI, US, UTC and W (herbarium codes from Holmgren & al. 1990), by Barkworth in CONC, LE, MO, UC, US, and UTC, and by review of numerous publications. The specimens examined included type specimens of most of the species involved. We have also examined specimens from numerous other herbaria as part of our earlier studies. Such specimens have not contributed directly to this paper, but have been important to the development of our understanding of Nassella.

The distribution of each species was recorded, at the country level, inititally in Excel 2000 (Microsoft 1999); Tables 1 and 2 summarizes these results. Table 3 presents a list of publications we consulted in preparing the distribution table and Table 4 lists voucher specimens for new or otherwise significant distribution records. Tables 5 and 6 summarize the morphological characteristics of each species. Only characters generally included in descriptions of the Stipeae are considered. The purpose of these tables is merely to provide a guide to the identification of the species; they should be used in conjunction with more complete descriptions. In general, Torres identified and provided the data for South American taxa; Barkworth identified and provided data for North American taxa.