A generic revision of Portulacaceae tribe Montieae using techniques of numerical taxonomy

Using a variety of clustering and ordination techniques on data from 37 species or species complexes recognized within the Portulacaceae tribe Montieae, a classification is proposed in which two genera, Claytonia and Montia, are recognized. Claytonia is distinguished from Montia by the possession of a basal leaf rosette, a scape-like stem with a pair of opposite leaves, and tricolpate pollen; this circumscription agrees with that originally proposed by Greene in 1891 and endorsed by Swanson (1966) in his review of relationships in the group; it differs, however, from that adopted in most recent Floras in that it includes the annual Limnia group in Claytonia. Within Claytonia, four sections are recognized, while nine are distinguished within the more variable Montia; the latter correspond to the segregate genera recently adopted by Nilsson and Yurtsev. A taxonomic synopsis is given of the genera, sections, and species, with keys to the genera and sections recognized. Three new combinations at sectional level (Montia sections Mona, Claytoniella, and Maxia), one at species level (Montia vassilievii), and two new varietal names are proposed.