Astragalus scutaneus Barneby, Amer. Midl. Naturalist

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

89. Astragalus scutaneus Barneby, Amer. Midl. Naturalist 55: 502. 1956

Type:— MEXICO, Jalisco, sandy shore at west end of Lake Chapala , 14 July 1940, C. L. Hitchcock & L. R. Stanford 7166 (holotype: WS Not seen: isotype: RSA 0003102 digital image!, OSC 0001444 digital image!, RSA 0003101 digital image!, GH 00059440 digital image!, RM 0002459 digital image!, UC 710966 digital image!, CAS 0000801 digital image!) .

Annual. Stems up to 45 cm long, commonly single from base, somewhat strong, striate, occasionally with purple tones, minute strigose, trichomes up to 0.5 mm long, straight, appressed. Stipules 2.5–4 mm long, semi-clasping or free, not connate, triangular, the upper ones mostly free. Leaves 5–9 cm long, leaflets 15–23, 5–15 mm long, linear, oblong, lanceolate to obovate, truncate or distally retuse, adaxially glabrate o scattered pubescent. Peduncles 2.5–6.5 cm long, ascending, straight or almost so; the racemes 1.2–6.5 cm long, dense, flowers 16–40. Flowers blue-purple, lilac, purple veined; the calyx 2–3.5 × 1.7–2 mm, densely strigose, trichomes black or black with few white ones mixed, the tube 1–1.5 mm long, campanulate, basally inequilateral (therefore, the hole, oblique to subgibous, with purple tones, the teeth 1.1–1.5 mm long, subulate to triangular; the banner 5.2–6 × 3.7–4 mm, obovate-flabellate, basally narrowed, distally retuse; the wings 5.2–5.5 × 1.5–2 mm, the claw 1.6–2 mm long, the blade 4–4.2 mm long, triangular, oblong, oblique distally; the keel 3.9–4.4 × 1.6–1.8 mm, the claw 1.7–2.1 mm long, the blade 2.3–2.9 mm long, diatally oblique, obovate or almost circular. Pod 5–9.8 ×| 6–7.8 mm, sessile, broadly elliptic, or almos circular, deflexed, dorsoventrally compressed contrary to the septum, simulating a “car windshield” or strongly arched flattened, slightly retuse, distally abruptly apiculate, 0.8–1.5 mm thick, the valves, thin, green, scattered strigose, turning papery, green-ochre, sometimes with purple tones, dark-brown or dark-purple, diaphanous, reticulate; septum incomplete; ovules 10–12; seeds 1.8–2.1 mm long, mitten shape, green-olive or brown, sometimes with purple tones, opaque.

Distribution:— Endemic to Mexico, southern and southwestern Mexico; in Guanajuato and Jalisco, also in the northern region, in southwetern San Luis Potosí (Salinas Municipallity) bordering Aguascalientes and Zacatecas ( Fig. 25 ).

Habitat:— Lakeshores; playas with saline soils; croplands; subtropical scrublands; Acacia scrublands; halophilous; temporary ponds; mezquite scrublands; sulphur springs; flood areas; brackish soils.

Comments:— Species distinctive by its almost planar, laterally compressed, curved or arched, strigose pods and racemes that are 20–40 flowered.Another species with a similar pod shape is A. brazoensis (Tamaulipas and Coahuila), although the latter has racemes with fewer flowers, 7–25, the pod glabrous, and elevated on a small gynophore (1.5 mm long or shorter).

Specimens examined:—GUANAJUATO: 22 October 1995, 2 km al S de Caleras , de Obrajuelo, Mpio. Apasco El Grande, Rzedowski 52955 ( IEB) ; 9 July 2002, 2 km al NW de Cupareo , Mpio. Salvatierra, Rzedowski 53958 ( IEB) ; 17 October 2001, 2 km al S de Calera de Obrejuelo , Mpio. Apasco El Grande, Rzedowski 53838 ( ENCB, IEB, MEXU) . JALISCO: 19 August 1902, Constancia Sta , near Guadalajara, C. G. Pringle 11362 ( US) ; 18 May 1969, Norte de Zacolaco , Mpil. Zacoalco de Torres, J. L. Íñiguez D. 1350 ( IBUG) ; 11 May 2000, a 1 km del abrevadero Jal. Mpio de La Boca , J. L. Álvarez s.n. ( IBUG) ; 12 April 1983, Libramiento Chapala-Jocotepec , a orillas del Lago, Mpio. Chapala, J. Cervantes R. 27 ( IBUG) ; 13 June 1983, Ribera Norte del Lago de Chapala , Mpio. Jamay, Estrada Faudón s.n. ( IBUG) ; 18 May 1969, Norte de Zocoalco , L. Ma. Villarreal de Puga 3049 ( ENCB, IBUG, IEB) , 18 May 196?, N de Zacolaco, L. M. Villarreal de Puga 3072 ( IBUG) ; 5 July 1987, 500 m all W de Los Pozoz , Mpio. Acatlán de Juárez, J. A. Machuca 5933 ( IEB) . SAN LUIS POTOSÍ: ¿-¿-1989, Las Terrazas del Cono , Ejido Nuevo Centro de Población La ¨paz,, Mpio. Salinas, A. Gómez G. s.n. ( ENCB)

Figures

FIGURE 25. Map showing the distribution of Astragalus sanguineus, A. scalaris, A. scutaneus, A. sinaloae, and A. spellenbergii in Mexico.