Despite being strongly recovered as monophyletic by molecular studies, Commelinales completely lacks any morphological support or circumscription. It is also the Monocot order that suffered the most striking changes across different classification systems, with its type family, Commelinaceae, being the only consistent member since its proposition. The order currently consists of Commelinaceae, Haemodoraceae, Hanguanaceae, Philydraceae and Pontederiaceae, presenting a Pantropical distribution and great ecological and morphological diversity. Based on extensive field, cultivation, ecological, herbarium, botanical illustration and literature research, I present the first morphological phylogeny for Commelinales, based on an extensive 600-character matrix, sampling almost a third of the species in the order. All five families are recovered as monophyletic, with 49 of the 59 currently recognised genera also recovered as monophyletic. The M P and BA topologies are greatly congruent with the available molecular hypotheses for Commelinales, highlighting the importance of morphology in understanding the systematics of plant groups. Almost all genera are morphologically supported by at least one exclusive synapomorphy. Thus, based on a combination of morphological and molecular data, Aneilema, Callisia, Coleotrype, Elasis, Thyrsanthemum, Tricarpelema and Tripogandra (Commelinaceae) are recircumscribed to represent monophyletic genera. Five new genera of Commelinaceae are described, in addition to the reestablishment of Aploleia, Cuthbertia, Gibasoides and Hadrodemas (Commelinaceae), and Orthotylax (Philydraceae). The circumscription of Anigozanthos (Haemodoraceae) is broadened to include Macropidia, Conostylis (Haemodoraceae) is broadened to include Blancoa, and Wachendorfia (Haemodoraceae) is broadened to include Barberetta. Finally, I propose an updated classification for Commelinales, recognising two suborders, one superfamily, five families, four subfamilies, 10 tribes, 13 subtribes (four of them newly described here), and 64 genera (five of them newly described here).
Marco O. O. Pellegrini (Wed,) studied this question.