The aims of the present study were to elucidate the relationships of the New World Lotus species groups, subgenera Acmispon Raf. (sections Microlotus Benth. and Simpeteria Ottley), Hosackia Benth. and Syrmatium Vog., and to compare these results with previous classifications and recent morphological and molecular phylogenetic hypotheses. A numerical taxonomic study using unweighted pair-group arithmetic average clustering was performed. The phenogram was generated from 34 operational taxonomic units (OTUs) × 41 characters (four vegetative characters and the basic chromosome numbers, 16 epidermal traits and 20 reproductive characters). The epidermal microcharacters (epidermal cells, stomata, stomatal index and trichomes) are described and summarised for 18 species of Hosackia and Syrmatium, and the remaining characters were derived from the literature. Phenetic results resolved four groups of species which coincide with the new genera Acmispon, Hosackia Douglas ex Benth., Ottleya D.D.Sokoloff and Syrmatium proposed, having taken into consideration the most recent morphological and phylogenetic hypotheses.