Phaseolus purpusii Brandegee (1912: 271) [clade A; sect. Pedicellati (Benth.) Freytag].

TYPE: CA Purpus 5196 (HOLOTYPE: UC-149841; ISOTYPES: BM, G, GH-64102, L-501280, MO-1731111, P).

Its deeply lobed narrow leaflets (with main nerves almost perpendicular) incite to maintain it separate from P. pedicellatus, while keeping it in the section Pedicellati. Few collections are known from W San LuÍs PotosÍ, Mexico. It is not mentioned in the “Vascular Plants of the Americas,” while P. pyramidalis Freytag belonging to the same section is cited. The author would agree on considering the latter as a synonym of P. grayanus (Delgado-Salinas et al. 2006) .

Specimen: MEXICO. San Luís Potosí: R Grether 782 (MEXU-274666).