68. Astragalus parvus Hemsl., Biol., Biol. Cent.- Amer., Bot. 1: 266. 1880

Type: — MEXICO, North Mexico, San Luis Potosí, 6000 to 8000 feet, Parry & Palmer 174 (holotype: K000478271 digital image!; isotype: P00585136 digital image!, MO-128314 digital image!, NA0095604 digital image!, TEX-LL00371246!, NY00005826!, ISC-v-0000331 digital image!, US00001516 digital image!, PH00005499 digital image, BM000931685 digital image!, PH00005498 digital image!, GH00059427 digital image!).

Tragacantha parva (Hemsl.) Kuntze, Revis. Gen. Pl. 2: 947. 1891. — Hamosa parva (Hemsl.) Rydb., Bull. Torrey Bot. Club 54: 335. 1927.

Astragalus schaffneri M. E. Jones, Rev. N.-Amer. Astragalus 276. 1923.

Perennial. Stems up to 20 cm long, ascendant or spreading and diffuse, minute strigose, the trichomes up to 0.5 mm long. Stipules 1.5–4.7 mm long, lanceolate to triangular, free, not connate. Leaves 1.5–9 cm long, leaflets 7–19, 1.5–12 mm long, linear, oblong, oblanceolate to elliptic, obtuse to retuse, adaxially glabrate. Peduncles 2–7 cm long, suberect, deflexed with age; the racemes 0.4–2.4 cm long, flowers 3–14. Flowers purple to pale-purple; the calyx 4–5.1 × 1.3– 2.2 mm, trichomes white, dense, the tube 2.3–3.1 mm long, campanulate to turbinate, white or occasionally pinkish; the banner 7.4–10 x 3.4–5.8 mm, recurved, obovate to rhombic; the wings 2.8–3.1 × 1.3–2 mm, the claw 2.6–3.2 mm long, the blade 4.7–6.6 mm long, linear, oblong to obovate, apically truncate or obtuse; the keel 5.4–6.2 × 1.4–2 mm, the claw 2.7–3.1 mm long, the blade 2.7–3.2 mm long, obovate. Pod 8–20 × 2–3.5 mm, ascendant, sessile or elevated from the receptacle by a tiny gynophore, triquetrous, linear to oblong, basally obtuse, distally contracted in a short, triangular beak, ventrally keeled, lateral faces flattened or somewhat rounded and convex with age, dorsally widely sulcate, the valves minute strigose, greenish or sometimes purple, papery, ochre, septum complete or incomplete; ovules 12–26; seeds 1.6–2.3 mm long, mitten shape, smooth, rarely rugose.

Distribution:— Endemic to Mexico, registered in northeastern Mexico in Nuevo Léon, adjacent to the geopolitical border of Coahuila, southwestern Tamulipas, south of San Luis Potosí, Zacatecas and a secluded location on the southern Puebla, almost on the geopolitical border with western Oaxaca (Fig. 21).

Habitat:— Calcareous and bare soils; pine forest; desert scrubs with creosote bush, mezquite and prickle pear; arid scrublands; disturbed areas with grasses and prickle pear; halophytic grasslands; oak forest; 1820–1880 m.

Comments:— In northeastern Mexico, A. parvus is distributed in areas where A. coahuilae, A. emoryanus, A. nuttallianus and A. mario-sousae are found, those species have purple or pink flowers, sessile triquetrous pods and, simple but not retrorse pubescence. Except for A. parvus with perennial habit and short (9 mm long or shorter pod), none of the species mentioned has this combination of characters.

Specimens examined:— DURANGO: 25-VII/5-VIII, 1906, Otinapa, E. Palmer 394 (US). JALISCO: 22/ 24 June 2004, Nopalera silvestre Rancho La Luz, camino vecinal Vaquerias-Las Papas, L. A. García R. 895 (IBUG). NUEVO LEÓN: 7 March 2003, Ejido San Joaquín, por la Carretera San Roberto-San Rafael, Mpio. Galeana, E. Estrada 15278a (CFNL); 5 July 2000, Ejido la Soledad, Mpio. Galeana, E. Estrada 11431 (CFNL); 16 May 1985, San Gerardo, Mpio. Galeana, G. B. Hinton 18831 (CIIDIR, ENCB, MEXU, TEX-LL); 25 April 1981, Santa Rita, G. B. Hinton 18182 (ENCB, MEXU); 13 May 1992, San Juan Puente y Avilés, Mpio. Galeana, Hinton 21944 (IEB). PUEBLA: VIII-1908, In the Vicinity of San Luis Tultitlanapa, Puebla, near Oaxaca, C. A. Purpus 3208 (JEPS); 25 April 1981, Santa Rita, Hinton et al., 18182 (ENCB, MEXU). SAN LUIS POTOSÍ: 20 August 1974, 46.0 mi. SE of the city of Zacatecas, 5.7 mi. SE of the Zacatecas state line along heavily grazed right of way of Highway 49, R. Spellenberg 3799, J. Syvertsen (NY, TEX-LL); 20 February1905, Chiefly in the region of SLP., C. C. Parry 174 (NY). 5 July 1987, About 9 mi E of San Luis Potosi on Hwy 86 between San Luis Potosi and Cd. Valles; 2.9 mi W of jctn with rd to Valle de Zaragoza, M. Luckow 2690 (NY, TEX-LL); 20 September 1961, Pastizal de Villa de Arriaga, A. Gómez G. 276 (NY). TAMAULIPAS: 11 July 1949, 3 mi nof Miquihuana, in pine forest, Stanford, Lauber, Taylor 2395 (JEPS). ZACATECAS: 3 August 1975, Km. 9, camino La Prudencia— Pinos, N. Becerra s.n. (MEXU).