Astragalus gentryi Standl., Field.

Castillón, Eduardo Estrada, Quintanilla, José Ángel Villarreal, Delgado-Salinas, Alfonso & Rebman, Jon P., 2023, The genus Astragalus (Leguminosae: Papilionoideae: Galegeae) in Mexico, Phytotaxa 586 (1), pp. 1921-1935 : 1921-1935

29. Astragalus gentryi Standl., Field. Mus. Bot. Ser. 22: 22. 1940

Type:— MEXICO, Sonora, Rio Mayo, February 1930, H. S. Gentry #xo (holotype: F0058939F digital image!; isotype: Sonora, San Bernardo, Rio Mayo , February 1934, H. S. Gentry s.n. ARIZ-BOT-0004068 digital image!, ARIZ.BOT-0004069 digital image!, San Bernardo, Rio Mayo , 23 Febraury 1935, H. S. Gentry 1345 MICH1107107 digital image!).

Annual o r perennial. Stems up to 30 cm long, prostrate or creeping and with radial growth, minute strigose, the trichomes appressed to subappressed, up to 0.6 mm long, white. Stipules 2–5 mm long, semi-clasping, not connate, dorsally glabrate or almost so, margins ciliate. Leaves 1.5–8 cm long, leaflets 11–17, 2–10 mm long, ovate to elliptic, obtuse, truncate, retuse or mucronate, adaxially glabrate. Peduncles 4–10 cm long, straight or curved; the racemes 1–4.8 cm long, short, dense remaining so until flowers opens or lax with age, flowers 4–12, spreading to ascending. Flowers pink, reddish-lavender, fading purple, purple to violet; the calyx 4.8–6.3 × 1.6–2.6 mm, minute strigose, trichomes white and black mixed, sometimes all white, the tube 3.3–4.3 mm long, subcylindrical, campanulate to oblong, sometimes basally inequilaterous, the teeth 1.4–2.2 mm long, papery; the banner 7.6–11.2 × 4.5–6 mm, widely obovate, obtuse to retuse distally, recurved; the wings 6.6–9 × 1.5–2.2 mm, the claw 3.3–4.8 mm long, the blade, 4–4.7 mm long, narrow oblanceolate; the keel 7.1–9.3 x 1.6–2.4 mm, the claw 3.5–5 mm long, abruptly incurved, equal or longer than wings; Pod sessile, 10–15 × 2.5 mm, ascending, linear to lanceolate, basally rounded, gradually narrowing and ending in a triangular apex, triquetrous, laterally compressed or flattened or almost so, ventrally carinate, lateral angles obtuse, dorsally and narrowly sulcate, the valves papery, ochre to greenish, minute strigose, reticulate perpendicularly, septum complete, the pod thence bilocular; ovules 12–18; seeds 1.4–1.5 mm long, brown, smooth, somewhat opaque.

Distribution:— Endemic to Mexico. Restricted to northwestern Mexico, mountains of the geopolitical border of Sonora (Yécora, Vallecitos, Cebadilla, Casa Blanca, Maicoba, El Álamo, Chinaguito, Calabazas) and Chihuahua (Batopilas, Nabogame, Maguarichi, Yepachi, Tubares, Guinoloza, El Fuerte and San Ignacio) and mountains in centraleastern Sinaloa (Bamepa, Bamopa, Maturipa and Amoles) in close proximity to extreme northwestern Durango ( Fig. 8 ).

Habitat:— Volcanic slopes and rocky igneous slopes; clayey and yellow soils; moist soils with organic matter; roadside, streams and rivers; canyon bottom; damp and cool canyons, with cypress-oak-pine; oak-pine forest; riparian conifer forest with oak and grassland; oak-pine-madroño forest; riparian forest with cypress, juniper; grasslands in hillsides; along streams; 1500–1933 m.

Comments:— So far as we know, A. gentryi is the only species, at least in Mexico, in which the keel petal is equal or lightly longer than the wing petals.

Specimens examined:—CHIHUAHUA: 17–25 April 1948, Rancho Byerly , Sierra Charuco, H. S. Gentry 8024 ( CAS, MEXU, NY, US) ; 27 September 1983, Loc. 4 km, al W de Talayotes o 35 km, al E de Yecora , P. Tenorio L 4535, C. Romero de T. ( NY) ; 1 May 1987, Nabogame, J. E. Lafferriere 421 ( NY) ; 27 April 1985, ca. 25 air miles SW of San Juanito, Maguarichi, igneous rock, canyon above village, R. Spellenberg 8099, R. Soreng, R. Corral, J. Cornelius, C. Spurrier, T.K. Todsen ( MEXU) . SINALOA: 17–24 March 1945, Los Pucheros , Sierra Surotato, H. S. Gentry 7212 ( NY) ; 8 March 1985, Badiraguato, +– 11 km. de la brecha Surutato , Sta. Rita, R.A. González, M. A. Armenta P., J. A. Méndez A. 173 ( MEXU) . SONORA: 8 April 1982, Sierra Madre Occidental, along the old dirt road from Santa Rosa to Yecora, 8 miles east of Santa Rosa, about 10 miles west of Yecora , about 33 miles (airline) NE of Movas, A. C. Sanders 2646, K. Kirkland, D. Emery ( NY) ; 4 May 1995, Arroyo, 3–4 km north-northwest of El Kipor ( Quipur ), T. R. Van Devender 93-380, A. L. Reina ( NY, TEX-LL, USON) ; 27 September 1983, 4. Km. al W de Talayote, camino a Yécora, o 35 Km. al E de Yécora, Limites de Sonora y Chihuahua, R. Torres C. 3828, P. Tenorio L. ( ANSM, MEXU, NY) ; 11 October 1933, H. S. Gentry 523 ( CAS) ; 29 March 1997, Ciénega de Camilo, 6 km east of El Kipor , 10 km of west of Chihuahua brederon Mex. 16, T. R. Van Devender 97-403, A. L. Reina G. (, USON) ; 19 February1997, CA 7.5 KM e OF Yecora on Mex 16 at Yecora , T. R. Van Devender 97-145, A. L. Reina, M. Kaib ( USON) ; 22 March 1992, Yécora — 1.5 km E of Yecora towards Maycoba along MEX 016, near km 281, on old river terraces around first barranca E of village, Eggli, Nyffeler, Struppy, Thiede 2031 ( MEXU) ; 12 March 1996, Yécora — 8.9 km east of Yecora on Mex. 16, T. R. Van Devender 96-91, A.L. Reina, S. L. Friedman, W. Trauba ( MEXU) ; 12 March 1996, Yécora, 8.9 km east of Yecora on Mex. 16, A. L. Reina 96-43, T. R Van Devender, S. L. Friedman ( MEXU) ; 27 September 1983, 4 km, al W de El Talayote ó 35 km, al E de Yécora , limites de Sonora y Chihuahua, P. Tenorio L. 4535, R. Torres C. ( MEXU) ; 27 June 2007, Moris—Bermudez , T. R. Van Devender 2007-645, A.L. Reina, J. Veteto ( MEXU) ; 28 March 1997, T. R. Van Devender 97-387, Yécora — Maycoba, A. L. Reina G. ( MEXU) ; 15 May 2008, Ca. 1 km south of Maycoba along Río Maycoba , T. R. Van Devender 2008-196, A. L. Reina G. Z. Espinoza G. (, MEXU, USON) .

Figures

FIGURE 8. Map showing the distribution of Astragalus francisquitensis, A. gambelianus, A. gentryi, and A. giganteus in Mexico.