Astragalus racemosus Pursh var. racemosus Pursh, Fl. Amer. Sept. (Pursh)

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

80. Astragalus racemosus Pursh var. racemosus Pursh, Fl. Amer. Sept. (Pursh) 2: 740. 1813

Type:— USA, Louisiana, In Upper Louisiana. Bradbury , December 1811, J. Bradbury s.n. (holotype: PH (not found); isotype BM000522133 digital image!) .

Astragalus racemosus Pursh, Fl. Amer. Sept. (Pursh) 2: 740. 1813. — Tragacantha racemosa Kuntze, Revis. Gen. Pl. 2: 947. 1891. — Tium racemosum Rydb., Bull. Torrey Bot. Club 32: 659. 1906. — Astragalus racemosus Pursh var. typicus, Ced. Porter, Madroño 8: 99. 1945. — Astragalus racemosus Pursh var. brevisetus M. E. Jones, Proc. Calif. Acad. Sci. ser. 2, 5: 662. 1895; Tium brevisetum Rydb., N. Amer. Fl. 24(7): 386. 1929.

Astragalus galegoides Nutt. , Gen. N. Amer. Pl. 2: 100. 1818;

Perennial. Stems up to 75 cm long, strong, erect, suberect to decumbent, sometimes diffuse branched, densely and minute strigose, trichomes up to 0.6 mm long, appressed. Stipules 3–12 mm long, amplexicual and connate (the lowest ones), commonly bidentate, the lowest ones little wider than longer, rarely embracing the stem tightly, the middle ones connate but only to the middle of its length or only in the lower part, the upper ones free or almost so, triangular, wide triangular to triangular-lanceolate. Leaves 4–5.8 cm long, leaflets 10–37, 1–3.7 cm long, narrow linear, oblong to elliptic, of thick texture, glabrate, with minute papillae. Peduncles 3–11 cm long, erect or curved with age; the racemes 3–22 cm long, flowers 15–70. Flowers lavender, whitish, rose purple, concolor or the veins purple; the calyx 7.3–10.5 × 3.2–5.5 mm, cylindric, cylindric-campanulate, sometimes cylindric-turbinate, lavender to pinkish, fine strigose, trichomes white, or white and black mixed, rarely only black trichomes, the tube 4.7–9 mm long, basally truncate, the teeth 1.5–3.7 mm long, subulate; the banner 15.4–19 × 6–10.7 mm, recurved; wings 12.4–19 × 2.2–3.8 mm, the claw 5–8.2 mm long, the blade 8.7–12.4 mm long, oblong to oblanceolate; the keel 10.6–15.4 × 2.3–3.8 mm, the claw 4.7–8 mm long, the blade 7.2–10.3 mm long, oblique, obovate, incurved. Pod 14–30 × 3–6 mm, deflexed, stipitate (stipite 3.5–7.4 mm long), triquetrous, compressed, linear, oblong to elliptic, narrowed at both ends, occasionally basally somewhat truncate, distally ending in a cuspidate beak, straight to slightly curved, lateral and ventral faces acute but obtuse, doraslly and ventrally somewhat flattened, sometimes dorsally somewhat convex, the valves thin, glabrate, rarely minute strigose, turning papery, ochre or green, shiny, reticulate; septum absent or scarcely developed, incomplete; ovules 12–22; seeds 2.6–3.3 mm long, mitten shaped, brown, smooth or little shiny.

Distribution:— Locally distributed in three areas of northeastern Mexico, Nuevo Léon (Galeana), Zacatecas (Matías Ramos) and San Luis Potosí (Salinas). Also, in Canada and USA ( Fig. 23).

Habitat:— Calcareous and gypsic soils; plains; halophytic grasslands with prairie dog colonies; adjacent to water deposits in saline areas; 1600–2000 m.

Comments:— The calcareous or gypsic soils of northeastern Mexico are home to various species of Astragalus , many of which are restricted to grasslands and semi-arid shrublands such as: A. coriaceus , A. diphacus , A. hypoleucus , A. mollissimus var. irolanus , A. nuttallianus var. austrinus , A. racemosus var. racemosus , A. sanguineus and A. wootonii var. candollianus Of these, only A. hypoleucus , A. nuttallianus and A. racemosus possess triquetrous pods, but can be easily differentiated by the presence of dolabriform trichomes in A. hypoleucus and the sessile pods of A. nuttallianus .

Specimens examined:— NUEVO LEÓN: 19 July 1999, Ejido La Casita , por la carretera San Rafael-La Hediondilla, Mpio. Galeana, E. Estrada 10309 ( CFNL) ; 4 August 1999, Ejido La Hedionda , Municipio Galeana, E. Estrada 10495, C. Yen ( CFNL) ; 3 June 2003, Ejido La Hediondilla y Ejido La Casita , E. Estrada 15891 ( CFNL) ; 10 June 1982, San Gerardo , Mpio. Galeana, Hinton 18372 ( IEB, TEX-LL) ; 24 May 1973, 59 km N. of San Roberto Junction on the Matehuala-Saltillo highway, 19 km S. of the Coahuilla state line, M. C. Johnston 11207, T.L. Wendt, F. Chiang C. ( MEXU) . SAN LUIS POTOSÍ: 23 April 1963, Laguna de Salinas , A. Gómez 834 ( ENCB) , 835 (ENCB, MEXU, NY); 30 June 1979, Mpio. Salinas , i km al N de Salinas, E. García M. s.n. ( ENCB, MEXU, NY) . ZACATECAS: 5 May 1892, Ramos, M. E. Jones 150 ( CAS) .