Astragalus allochrous A. Gray,

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

2. Astragalus allochrous A. Gray, Proc. Amer. Acad. 13: 366. 1878

Type: — USA, Near Wickenburg, Arizona, E. Palmer 588, 1876 (Holotype: GH 00058622 digital image!; isotype: NY!) .

Phaca allochroa (A. Gray) Rydb., Fl. Rocky Mts. 487: 1063. 1917.

Annual, or perennial for a short time. Stems up to 50 cm long, suberect to decumbent or when prostrate, the branches radiating from the center and forming a circle, frequently with purple tones at base, strigose, trichomes up to 0.7 mm long, adpressed. Stipules 1.4–7 mm long, triangular, ovate to triangular, acuminate, clasping, not connate, more evident in the lower nodes, surrounding the half or almost the complete stem´s circumference in upper nodes. Leaves 3–10 cm long, leaflets 9–21, 0.4–2.1 cm long, linear, oblong, elliptic to obovate or oblanceolate, acute, obtuse or retuse apically, occasionally mucronate, adaxially pubescent or glabrate. Peduncles 3–11 cm long, curved and ascendant, the external ones humistrate and ascending when fruit rippens; racemes 2–12 cm long, lax, flowers 10–30, ascendant at the beginning. Flowers pink, reddish to purple, white or whitish, becoming violet when dry, the banner white, purple veined, wings and keel purple; the calyx 3.6–5.6 × 1.9–3.6 mm, strigose, trichomes white or, black and white mixed, tube commonly campanulate, 2.4–3.5 mm long, the teeth 1–2.5 mm long, subulate to lanceolate, ventral pair the longer; banner 7–9.4 × 5–7.2 mm, ovate to spathulate; the wings 6.5–8.3 × 2.2–2.7 mm, claw 2.2–3.1 mm long, blade 4.5–4.7 mm long, oblique-obovate; the keel 6.2–7.5 × 2.1–2.6 mm, the claw 2.5–3.2 mm long, the bade 3.8–4.5 mm long, incurved, oblique-triangular. Pod 2–4.5 × 1–2 cm, sessile or minutely elevated on the receptacle, spread to pendulous, elliptic, obliquely-elliptic, inflated, bladder-like, with asymmetric margins, narrow at both ends, the apex ending in a 3–6 mm long beak, dorsal suture strongly convex, valves strigose, at times with purple tones, papyraceous, translucent, lustrous, ochre, transversely reticulated, septum absent, soon caducous; ovules 10–21; seeds 2.5–3.2 mm long, semicircular, brown, greenish-brown, sometimes mottled with purple.

Distribution:— In Mexico, distributed in the northwestern region, north (Nogales, Sáric, Ímuris, Magdalena, Benjamín Hill) and northeast (Cananea, Agua Prieta, Nacozari, Fronteras, Esqueda) Sonora, central (Chihuaua), western-central and northwest (Janos, Nuevo Casas Grandes, Cuauhtémoc) Chihuahua. Also, in Arizona and New Mexico ( USA) ( Fig. 2 ).

Habitat:— In granite, gravel, sandy, and occasionally in calcareous soils; stony and rocky slopes and streams; Sonoran desert scrub; desert plains with scrublands and sahuaro; desert scrubland with columnar cacti; grasslands with Josua tree and creosote bush; mesquite scrublands; grassland with mesquite and oaks, adjacent to marshes; lowlands with oaks and grasses; frequent roadside; roadside with burr sage; along marsh; 825–1450 m.

Comments:— This species is sympatric and morphologically similar to A. wootoni . Tthese two species can be differentiated by their pod shape, as A. wootoni has a symmetrical pod, the margins of the valves are equilateral seen in profile view, in addition, the pod lacks a peak, if present, this is minute.

Specimens examined:—CHIHUAHUA: 4 March 1977, 43 mi. sw of Palomas at minera Bismark turnoff, N. D. Atwood 21592, J. Spencer ( NY) ; 9 April 1997, E. Estrada 6897, C. Yen. ( CFNL) SONORA: 8 March 2003, Reservoir El Yeso , ca. 6.5 km southeast of Magdalena, north of SON 54 (to Curcurpe), T. R. Van Devender 2003-154 ( MEXU, NY) ; 4 April 2007, Arroyo Guadalupe, Rancho Guadalupe , Ejido Oquita Montenegro , ca. 37 km east of Agua Prieta, A. L. Reina G. 2007-370, T.R. Van Devender, J. F. Wiens, J. Moore ( NY) ; 9 April 2003, 1.4 km south of Agua Prieta on Mex 17; Chihuahua desert scrub , T. R Van Devender 2003-357, A. L. Reina, G. Anderson ( CAS, MEXU) ; 4 April 1963, Sonora. 2 miles W of Santa Ana, Gentry 19892, Argüelles ( MEXU, US) ; 10 April 2003, Esqueda , A. L. Reina G. 2003-413, T. Van Devender, C. Anderson ( USON) ; 8 April 2003, Reservoir El Yeso, Mpio. Magdalena , ca. 6.5 km SE of Magdalena, T. R. Vand Devender 2003-154, A. L. Reina G. ( USON) ; 9 April 2003, 1 KM SOUTH OF Agua Prieta, on Mex. 17, T. Van Devender 2003-357, A. L. Reina, G. Anderson ( USON) ; 11 May 1948, Durango, 5.3 mi. no. of Esqueda on road to Agua Prieta, I Wiggins 11776 ( MEXU).

Figures

FIGURE 2. Map showing the distribution of Astragalus acutirsotris, A. allochrous, A. amphioxys, A. anemophilus, and A. aridus in Mexico.