100. Astragalus waterfallii Barneby, Leafl. W. Bot. 7: 31. 1953 Type: — USA, New Mexico, Eddy County, 21 miles west of Artesia, 12 April 1953, U. T. Waterfall 10615 (holotype: OKLA 100018 digital image!; isotype: CAS 0027730 digital image!, RSA 0003147 digital image!, MO-149300 digital image!, US 00001637 digital image!, GH 00059397 digital image!). Perennial. Stems short, up to 9 cm long, mainly acaulescent, pubescence dense, white, short stigose, the trichomes up to 0.7 mm long, straight, appresed. Stipules free to clasping, somewhat decurrent by a half or three quarters of stem´s circumference. Leaves 2–12 cm long, leaflets 9–25, 3–16 mm long, ovate, elliptic, ovate-oblong to oblanceolate, bicolored, brighter green and glabrous adaxially, abaxially dense pubescent. Peduncles 1.5–11 cm long, ascendant, soon deflexed and humistrate with age; the racemes 1.5–4 cm long, floweres 4–18. Flowers purple with white tones basally, the calyx 10–14 × 3.7–5 mm, tiny strigose, with white and black trichomes or both types mixed, the tube 8– 11.5 mm long, cylindric, with purple tones, the teeth 1.3–4 mm long, subulate to triangular-subulate; the banner18–23 × 6–11 mm, ovate to oblanceolate, strongly curved; the wings 17–22.5 × 2.1–3.5 mm, the claw 8–11.4 mm long, the blade 10–12.8 mm long, lanceolar obovate; the keel 14.5–19 × 2.8–3.6 mm, the claw 7.5–10.9 mm, the blade 7.4–9.6 mm long, lanceolate-obovate, incurved. Pod 1.8–3.8 × 0.5–0.8 cm, sessile, humistrate but ascending, triquetrous or trigonous but little compressed laterally, incurved, oblong to oblong-elliptic or clavate-ellipsoid, gradually acute to the base, abruptly acute at apex, ending in a cuspidate small beak, ventrally carinate, lateral faces rounded, dorsally slightly sulcate, the valves leathery, fleshy to stiff-papery, brown to black-brown, finely reticulated and wrinkled, septum complete, the pod thence bilocular; ovules 28–38; seeds 2.2–3.2 mm long, mitten shaped, brown to lightbrown, occassionally with purple spots, shiny. Distribution:— Rare in Mexico, recorded and reported (Barneby, 1964) for northern Chihuahua (Sierra Rica, 1881, Havard 31 (GH)), and Coahuila (Sierra de Parras, X-1910, Purpus 4671 (UC)). Also, in New Mexico and Texas (USA) (Fig. 27). Comments: Species easily identified by its short stems or even acaulescent ones. Specimens examined: — CHIHUAHUA: (cited by Barneby, 1964, page 653, Map 83). Material not seen for Mexico. TEXAS (very near to the Mexican border): 26 April 1961, Culberson, Just NE of San Antonio Peak, Sierra Tinaja Pinta, on upland plateau, D. S. Correll & R. C. Rollins 23877 (TEX-LL); 27 March 1932, E. Whitehouse 128d (TEX-LL); 16 May 1959, Culberson, Head of pass in vicinity of roadside park, Guadalupe Canyon, D. S. Correll & I. M. Johnston 21996 (TEX-LL); 28 Febraury 1957, Presidio, 25 mi. SW Marfa toward Shafter, B. H. Warnock 14343 (TEX-LL).

Published as part of Castillón, Eduardo Estrada, Quintanilla, José Ángel Villarreal, Delgado-Salinas, Alfonso & Rebman, Jon P., 2023, The genus Astragalus (Leguminosae: Papilionoideae: Galegeae) in Mexico, pp. 1921-1935 in Phytotaxa 586 (1) on pages 1921-1935, DOI: 10.11646/phytotaxa.586.1.1, http://zenodo.org/record/7703999