Phaseolus acutifolius var. acutifolius
Leaflet blades ovate to widely ovate, terminal ones 2.5–8.5 × 1–5 cm, base rounded, apex acute. Legumes 36–70 × 5–9 mm. Seeds 4–10, 3–6 × 3.3–5.5 mm. 2n = 22.
Phenology: Flowering Jun–Nov.
Habitat: Open pine-oak forests, mesquite thickets, grasslands, chaparral, scrub, igneous or limestone soils.
Elevation: 200–2000 m.
Distribution
Ariz., N.Mex., Tex., Mexico (Baja California Sur, Chihuahua, Coahuila, Colima, Durango, Jalisco, Nayarit, Sinaloa, Sonora).
Discussion
Variety acutifolius is found in central and southern Arizona, Catron, Doña Ana, Grant, and Luna counties in New Mexico, and Jeff Davis and Pecos counties in Texas.
The leaflets of the type collection of Phaseolus acutifolius, as well as others from specimens of western Texas, are characterized by having smaller and narrower leaflets than those from populations elsewhere.
The cultivated plants of Phaseolus acutifolius are classified under this variety, commonly having fruits 5–9 × 0.8–1.3 cm, from elastically to weakly dehiscent, and white, yellow-brown, tan-mottled, and blue-black seeds (R. C. Pratt and G. P. Nabhan 1988).
Selected References
None.