Astragalus pilosior R. W. Spellenb. & E. W. Anderson

70. Astragalus pilosior R.W. Spellenb. & E.W. Anderson, J. Bot. Res. Inst. Texas 13(1): 131–140. 2019

Type: — MEXICO, Chihuahua, Mpio. de Batopilas, on old Batopilas-Urique road, near top of ridge between Río Batopilas and Río Urique, 16.8 km SSE of junction witroad down to Urique, 25 km road km NW of crossing of Río Batopilas at La Junta, 1.75 km N of junction to Manzano, 30 March 2013, R. Spellenberg, W. Anderson 14532 (holotype: NMC not seen; isotype MEXU, NY (not found in those herbaria); paratype: Mexico, Chihuahua, Barranca Sinforosa, Rancho Coyeachic, 4 km E of Pino Gordo, 26°33’N 106°58’W, elev. approx. 2450 m, 8 March 1997, Mark Fishbein 2910 ARIZ 336765, Mexico, Mpio. de Guachochi, on Samachique-Batopilas road (Chih. Hwy. 185) 7.2 km S of junction with Creel-Guachochi highway (Chih. Hwy. 25); 12 April 20, R. Spellenberg & W. Anderson 14540 (MEXU, NMC, not found).

Perennial. Stems up to 55 cm long, branched or simple from the root, sometimes, the stems several cm below ground, sprawling to decumbent, white to ashy-pubscent, the trichomes 0.6–1 mm long. Stipules 4–5 mm long, of both types, the lowest ones clasping, shorter than the upper ones, white to light-green, the upper ones commonly free, foliaceous, lanceolate to acuminate, straight to reflexed, densely white-pubescent adaxially, abaxially with similar pubescence but less dense. Leaves 2–6 cm long, leaflets 9–19, 3–12 mm long, elliptic to obovate, rounded or shallowly notched apically, pilose abaxially, the trichomes, somewhat ascending and appressed, adaxial less densely so. Peduncles ascendant to incurved, 3–5 cm long; the racemes 10–35 mm long, 15–35 flowered. Flowers purple, blue with white tones, the banner with purple veins, ascending, declined soon, 5.5–6.7 mm long; the calyx 3.9–5.3 × 1.6–2.0 mm, scattered hairy, the tube 2.2–3 mm long, campanulate, the teeth 1.7–2.5 mm long; the banner 5–6.5 × 1.5–1.7 mm, wide oblong, rounded to truncate apically; the wings 5–7.1 × 1.3–1.4 mm, the claw 2.5–3 mm long, the blade 3.5–4.1 mm long, obliquely obovate, slightly incurved, apically rounded; the keel 5.3–5.8 x 1.7–1.8 mm, the claw 1.8–2.1 mm long, the blade 3.5–3.7 mm long, semi-ovate, wide acute apically; ovules 7–13. Pods crowded, pod stipitate, the stipe 0.4–0.8 mm long, hidden into the calyx, the body 9–12 mm × 2.6–3.2 mm, triquetrous, oblong to oblong-ovoid, incurved, basally cuneate, apically ending in a short, almost 2 mm long beak, ventral suture sharply angled, lateral faces convex, rounded, the dorsal suture deeply sulcate, septum complete, 3 mm deep, the valves green when young turning tan to brownish with age, with scattered hairy, the trichomes 0.5–0.7 mm long; seeds not seen.

Distribution:— Endemic to Mexico, recorded from few localities of the southwestern Chihuahua, Batopilas and Urique (Fig. 21).

Habitat:— Pine forest; 1900–2500 m.

Specimens examined:— CHIHUAHUA: 30 March 2013, Urique road, near top of ridge between Río Batopilas and Río Urique, 16.8 km SSE of junction with road down to Urique, 25 km road km NW of crossing of Río Batopilas at La Junta, 1.75 km N of junction to Manzano (18 air km SE of Urique, 9.4 km NNW of Batopilas), R. Spellenberg, W. Anderson 14532 (CIIDIR); 8 March 2013, Barranca Sinforosa, Rancho Coyeachi, 4 km al E de Pino Gordo, M. Fishbein 2910 (336765! Digital image, ARIZ).