A cladistic analysis of the Old World species of Lotus L. (Fabaceae : Loteae)

The diagnostic characters of the genus Lotus L. are a claw with a thickened infolded margin, diadelphous stamens, and a style hardened from the base. This genus contains about 100 species that are distributed throughout the w orld. To investigate the phylogeny of the Old World species of Lotus, subge nus Edentolotus, sections Krokeria, Xantholotus, and Erythrolotus, a cladis tic analysis was performed using 31 morphological characters. To test the p hylogenetic relationships among species of Lotus-Edentolotus andDorycnium, Pedrosia, andTetragonolobus, these taxa were included as part of the ingrou p. The polarity of the characters was based on the outgroup comparison meth od, using Anthyllis as one outgroup and Tripodion as another. The analysis with Anthyllis as outgroup yielded eight equally parsimonious trees (with a ll characters equally weighted), each with 62 steps, a consistency index of 0.53, and a retention index of 0.75. All trees (including the strict conse nsus tree from the eight initial trees) showed that genus Lotus, subgenus E dentolotus, and sections Xantholotus and Erythrolotus are polyphyletic, wit h only section Krokeria appearing as monophyletic. On the other hand, the g roups of species Lotus angustissimus, Lotus corniculatus, Lotus creticus, a nd Lotus peregrinus are monophyletic. Identical results were derived from t he data matrix using Tripodion as the outgroup. Results are compared with p revious cytogenetic and biochemical evidence.