Phylogenetic relationships in the monocot order Commelinales, with a focus on Philydraceae

To characterize higher-order phylogenetic relationships among the five families of Commelinales, we surveyed multiple plastid loci from exemplar taxa sampled broadly from the order, and froth other major monocot lineages. Phylogenetic inferences in Commelinales using parsimony and likelihood methods are congruent, and we find strong support for most aspects of higher-order relationship in the order. We obtain moderately strong support for the local placement of Philydraceae, a family whose position has proven particularly difficult to infer in previous studies. Commelinaceae and Hanguanaceae are sister taxa, and together they are the sister group of a Glade consisting of Haemodoraceae. Philydraceae, and Pontederiaceae; Haemodoraceae and Pontederiaceae are also sister taxa. Our sampling of Philydraceae includes all three or four genera in the family: we identify Philydrella as the sister group of a Helmholtzia-Philydrum clade, a resolution that is potentially consistent with several aspects of morphology.