Phaseolus acutifolius A. Gray (1852: 43)

Phaseolus acutifolius A. Gray (1852: 43) View in CoL [clade B; sect. Acutifolii Freytag]. TYPE: C Wright 1311 (LECTOTYPE: GH-64068 ) .

In the original description (p. 44) there is no mention of a specimen. However, through the work of George Freeman (1912, p. 20 and following) and his interactions with the staff of the Gray Herbarium, it was possible to locate and identify the type. Although the contribution by Asa Gray has been accepted for publication in March 1850, it has been published in March 1852. Two wild forms are often recognized, var. acutifolius and var. tenuifolius ( Delgado-Salinas 1985) ( Fig. 1 View FIG ). There might be ecological characteristics that separate these two forms ( Pratt & Nabhan 1988), with var. tenuifolius being a colonizer of open sunny, slightly more xeric habitats. This variety often displays narrow leaflets (width 4–10 mm), the lateral ones often sublobate at base, with heteroblastic development being more expressed as the stem gets exposed to direct sun light. But studies using molecular markers ( Muñoz et al. 2006; Blair et al. 2012) are less affirmative about the differences between the two forms, giving support to the synonymy proposed by Russ Buhrow (1983). Considered a member of the Vulgaris group ( Delgado-Salinas et al. 2006), it is here maintained apart as the phylogenetic distance to common bean is not the same as for the other members of this group ( Debouck 1999).

Specimens: U.S.A. Arizona: FS Coburn 1490 (ASU-292151). New Mexico: JT Columbus 1588 (NMCR). Texas: P Manning 4080 (K). MEXICO. Baja California Sur: R Moran 18725 (ARIZ-185218). Sonora: P Jenkins 88-329 (ARIZ-322133). Chihuahua: HS Gentry 2465 (ARIZ-300374). Coahuila: E Palmer 261 ( PH). Sinaloa: J González-Ortega 870 (ENCB). Durango: P Tenorio-Lezama 9850 (TEX-272994). Nayarit: G Flores-Franco 1249 (MO-3851303). Jalisco: R Lépiz-Ildefonso 125 (IBUG-208586). Guanajuato: LI Aguilera G. 293 (CHAPA). Michoacán: JN Labat 1279 (P).