Phaseolus angustissimus A. Gray (1853: 33)

Debouck, D. G., 2021, Phaseolus Beans (Leguminosae: Phaseoleae): A Checklist And Notes On Their Taxonomy And Ecology, Journal of the Botanical Research Institute of Texas 15 (1), pp. 73-111 : 80

Phaseolus angustissimus A. Gray (1853: 33) [clade B; sect. Rugosi Freytag ]. TYPE: C Wright 68 (distributed as 951) (SYNTYPES: GH-64073 ; ISOSYNTYPES: BM, K-H922/76-1, GH-64074 , MO-1731218 ) .

The original material (no. 951 in Gray’s herbarium, with “n. sp.” handwritten on the label, possibly by Asa Gray himself; Padovani & Cuccuini 2006 reported a series of handwritings) seems to refer to two gatherings, one made in New Mexico in July 1851 and another one made in Sonora in September 1851 (the plant to the left in GH-64073), thus the use of syntypes along Art. 9.5. of the Melbourne Code (2012). As noted by James Lackey (1983) this taxon has a tuberculate seed coat ( Fig. 5 ), different from the raised lines radiating from the hilum which can be seen in wild P.lunatus or P. microcarpus . It is a widespread species, growing in pine, oak, ash or plane forest or chaparral at 800–2400 m, with distribution well documented in S Arizona, S New Mexico and the W end of Texas, but with few records from N Mexico (although claimed to be present: Hermann 1966; Correll & Johnston 1970; Estrada & MartÍnez 2000). In the original description of P. angustissimus, Asa Gray (1853, p. 33) wrote “between San Pedro and Santa Cruz, Sonora, Sept.”. Two specimens of collection 951 have been found in PH and TCD with the indication of Sonora.

Specimens: U.S.A. Arizona: D Atwood 18881 (NY). New Mexico: ND Atwood 30820 (DAV-175765). Texas: TL Steiger 927 (NY).

Figures

FIG. 5.Seed coat of the Rugosi (top row:macrophotos of seed,scale in mm, by O.Toro,CIAT;lower row:scanning electronic microscope photographs (x 2,500, scale bar 10 microns,by J.A.Arroyave,CIAT) of: a. P.angustissimus (G40669,R Buhrow 85-1), b. P.carterae (G40675,León de la Luz 3751), and c. P.filiformis (G40510,VE Rudd 3396).