Astragalus brazoensis Buckl., Proc. Philad. Acad. Arts

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

8. Astragalus brazoensis Buckl., Proc. Philad. Acad. Arts 454. 1861

Type: — USA “Western Texas.” June 1861, S. Botsford W. (holotype: PH 00005241 digital image!; isotypus: GH 00058649 digital image!) .

Tragacantha brazoensis (Buckl.) Kuntze, Rev. Gen. 943. 1891. — Hesperastragalus brazoensis (Buckl.) Rydb. , Bull. Torrey Bot. Club 53: 166. 1926.

Annual. Stems few, up to 45 cm long, commonly shorter, decumbent, erect and to ascending distally, strigulose, the trichomes appressed or ascendant, up to 0.7 mm long. Stipules 1.5–4.5 mm long, semi-clasping or the lowest ones, almost completely clasping, not connate, ovate. Leaves 2–8 cm long; leaflets 11–13, 3–13 mm long, oblong-obovte to spathulate, retuse. Peduncles 3–11 cm long, straight and ascendant or curved; the racemes 1–3.5 cm long, flowers 7–25, deflexed with age. Flowers purple with white tones, whithish or bicolored, with lilac tones at the apical edges; the calyx campanulate, 2.7–4.1 × 1.6–2 mm, strigulose, with white and black trichomes mixed, the tube 1.5–2.5 mm long, purple or green, the teeth subulate, 1–1.8 mm long; the banner 5.3–8 × 3.6–5.6 mm, recurved, with lilac or purple tones on the edge, obovate, retuse; the wings 3.8–5.6 × 1.3–2.7 mm, oblancolate, the claw 1.6–2.3 mm long, the blade 3.8–5.6 mm long; the keel 4.5–5.9 × 0.8–2.1 mm, oblong-obovate, the claw 2–2.6 mm long, the blade 3–4 mm long. Pod pendulose, elevated in a glabrate gynophore 1.5–2.3 mm long, peltate, somewhat semicircular, dorsoventrally compressed, but somewhat inflate, on times wider than longer, 3.5–7 × 4.5–9 mm, retuse at both ends, with a conic, triangular-subulate apex 0.7–1 mm long, the valves hard, papery but stiff, glabrate, green, turning purple with age, brown or ochre, somewhat lustorous, with a complete septum, thence bilocular; ovules 4; seeds 2.2–3.2 mm long, brown to olive smooth.

Distribution:— Northeastern Mexico, extreme north of the state of Tamaulipas (Municipality of Matamoros) and Llano del [illegible..tijon?], R. Runyon 833 ( US); one record from Coahuila (Muncipality of Jiménez). Also, in Texas into the USA ( Fig. 3 ).

Habitat:—I nhabiting desert scrub and disturbed areas associated with weeds.

Comments:— Easily recognized by its peltiform shield-shaped, elevated pod. The other species with similar fruit shape is A. scutaneus (western Jalisco and San Luis Potosí), but, this later with sessile and strigose pods.

Specimens examined:— COAHUILA: 11 March 1991, Mpio. Jiménez, R. Solís s.n. ( ANSM); TAMAULIPAS : 10 April 1905, Matamoros, S. M. Tracy 9091 ( NY, US) ; 21 March 1876, Tamaulipas (perhaps Matamoros ) R. Runyon 833 ( US) .

Figures

FIGURE 3. Map showing the distribution of Astragalus arizonicus, A. brauntonii var. lativexillum, A. brazoensis, A. carminis, A. cenorrhynchus, and A. circumdatus in Mexico.