A REVISION OF DIARRHENA (POACEAE) IN THE UNITED-STATES

Cluster and principal coordinate analyses of Diarrhena americana (Poaceae) revealed two non-overlapping groups of OTU's corresponding to Diarrhena americana var. americana and var. obovata. A stepwise discriminant functions analysis used four characters to effect complete separation of the two groups of OTU's. Two caryopsis types-differing in size, shape, beak, and degree of pericarp-seed coat fusion-occur and are correlated with the two taxa. Consequently, recognition of two species is warranted, and the new combination Diarrhena obovata is made.