Subfamily Chloridoideae (Poaceae) in the New World includes 72 genera (61 native, 11 introduced), 678 species (607 native), and, including intraspeciﬁc taxa, 817 total taxa. The ﬁve largest genera are Muhlenbergia (147 species), Eragrostis (111), Sporobolus (76), Bouteloua (57), and Chloris (35). Three tribes are recognized in this study: Cynodonteae, Eragrostideae, and Zoysieae, with ten, three, and two subtribes, respectively. Cynodonteae, the largest tribe, comprise 58 genera and 451 species (67% of all New World chloridoids), including 25 genera (98 species, 22% of all New World Cynodonteae) with unknown afﬁnities (incertae sedis). In Mexico, the USA, and Canada there are 477 native and introduced chloridoid species (70% of all New World species), whereas in Central America (including the Caribbean) and South America there are 196 and 304 species, respectively. Mexico is the center of diversity with 343 species (51%). There appear to be ﬁve biogeographical patterns exhibited by New World chloridoid species: (1) North America, centered in northern Mexico and the southwestern USA, (2) southern South America, centered in northern Argentina, Paraguay, Uruguay, and southern Brazil, (3) northwestern South America, centered in Ecuador and Peru, (4) amphitropical disjuncts, occurring in North America and southern South America, and (5) widespread species, occurring in North America, Central America, and South America. Subtribes Boutelouinae (Bouteloua) and Muhlenbergiinae are predominantly North American, whereas Eragrostidinae (Eragrostis) and Chloridinae are better represented in the southern South American center. Two subtribes of Cynodonteae, Gouiniinae and Hilariinae, are described as new, and two others, Orcuttiinae and Traginae, are newly treated at that rank.
Peterson, Paul M.; Columbus, J. Travis; and Pennington, Susan J.
"Classification and Biogeography of New World Grasses: Chloridoideae,"
Aliso: A Journal of Systematic and Evolutionary Botany:
1, Article 43.
Available at: http://scholarship.claremont.edu/aliso/vol23/iss1/43