Phylogeny and subfamilial classification of the grasses (Poaceae)

A large collaborative effort has yielded a comprehensive study of the phylo geny and a new subfamilial classification of the grass family (Poaceae/Gram ineae). The study wa,, conducted oil all integrated and representative set of 62 grasses (0.6% of the species and ca. 8% of the genera) plus four outg roup taxa using six molecular sequence data sets (ndhF. rbcL, rpoC2, phyB, ITS2, and GBSS1 or waxy), chloroplast restriction site data, and morphologi cal data. A parsimony analysis using 21.13 informative characters (the comb ined analysis) resulted in a single most parsimonious tree 8752 step., with all RI of 0.556 and bootstrap Support of > 90% for more than half of the i nternal nodes. Significant relationships that appear consistently in all an alyses of all data sets and are strongly supported by the combined analysis include the following: Joinvilleaceae are sister to a monophyletic Poaceae : the earliest diverging lineages of the Poaceae are Anomochlooideae. Pharo ideae, and Puelioideae, respectively: and all remaining grasses form a clad e. Multiple monophyletic clades were recovered, including Bambusoideae s. s tr., Ehrhartoideae, Pooideae s.l., Aristidoideae, Danthonioideae, Chloridoi deae s. str., Chloridoideae s.l., Panicoideae, Parianeae, Olyreae s. str.. Oryzeae, Stipeae, Meliceae, Lygeum + Nardus, and Molinia + Phragmites. The PACCAD Clade is monophyletic, containing Aristidoideae, Danthonioideae. Aru ndinoideae s. str., Chloridoideae s.l.. Centothecoideae, Panicoideae. Eriac hne, Micraira,and Gynerium. Based on the phylogeny, a classification of 11 previously published subfamilies (Anomochlooideae, Pharoideae, Puelioideae, Bambusoideae, Ehrhartoideae, Pooideae, Aristidoideae, Arundinoideae. Chlor idoideae,Centothecoideae, and Panicoideae) and 1 new subfamily (Danthonioid eae) is proposed. Several changes in the circumscription of traditionally r ecognized subfamilies are included. Previous phylogenetic work and classifi cations are reviewed in relation to this classification and circumscription , and major characteristics of each subfamily are discussed and described. The matrix, trees, and updated data matrix are available at (http://www.vir tualherbarium.org/grass/gpwg/ default.htm).