Astragalus spellenbergii A. E. Estrada, S. González & Villarreal,, 2016

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

91. Astragalus spellenbergii A. E. Estrada, S. González & Villarreal, Phytotaxa 288(1): 92. 2016

Type:— MEXICO, Durango, Municipio de Pueblo Nuevo, Maíz Gordo , ladera, alt. 3043 m, 23 October 2010, C. Vázquez R. 40a & N. B. Cabada A. (holotype CIIDIR!; isotype CFNL!) .

Perennial. Stems short, up to 15 cm long, branched from base, decumbent to suberect, pilose to hispid, trichomes up to 1 mm long, extended or retrorsely extended, straight or slightly sinuosos, white. Stipules dimorphic, the lowest ones 2–2.6 mm long, connate-clasping, in nodes without leaves, apically free, the middle and upper ones 3–8 mm long, semi-clasping or free, ovate to triangular, apically abruptly acute. Leaves 1.1–5.5 cm long, leaflets 5–15, 3–9 x 1–5 mm, elliptic to oblong, apically rounded, pilose to hispidulous in both surfaces, abaxially denser. Peduncles 3.5–7 cm long, erect or ascendant, trichomes black and white mixed; the racemes 2–3 cm long, dense, compact, flowers 9–15, deflexed. Flowers yellow to ochroleucous; the calyx 4.3–4.7 × 1.4–1.7 mm wide, the tube 1.3–1.7 mm long, campanulate, inequilaterous o slightly oblique, pilose-hispidulose with black trichomes, rarely some white one present, the teeth 1.7–3 mm long, triangular; the banner 6.5–7.2 × 2.8–3 mm, elliptic, obovate to rhombic, distally obtuse to retuse, recurved; the wings 5.2–5.3 × 1.3–1.8 mm, the claw 2.2–2.3 mm long, the blade 2.9–3.1 mm long, oblong, distally oblique, apex rounded; the keel 4–4.2 × 1.6–1.8 mm, the claw 2 mm long, the blade 2–2.2 mm long, semiobovate, distally oblique and rounded; Pod deflexed, short stipitate (stipe 0.2–0.3 mm long), 7–8 × 2–3 mm, oblong, triquetrous, straight o slightly incurved, dorsally sulcate, ventrally concave keeled, basally rounded or slightly obtuse, distally ending in a short, acute, triangular beak, the valves green to yellowish, turning stramineous to dark-brown with age, densely hirsute to hispidulous, trichomes black, black or white and black and white mixed along ventral suture and white trichomes in the rest of the body, turning subglabrate or scattered hispid with age, imperceptibly reticulate, septum complete, the pod thence bilocular; ovules 6–7; seeds 2–2.2 mm long, mitten shaped.

Distribution:— Endemic to Mexico; currently, A. spellenbergii in known only from the type locality at Pueblo Nuevo, Durango ( Fig. 25 ).

Habitat:— Associated with oak-pine forest, and alpine meadows; 2800–3650 m.

Comments:— This species is morphologically similar to A. purpusii and A. micranthus , both with purple flowers. Although in A. micranthus the flowers become yellowish when drying, and A. spellenbergii can be distinguished by its retrorse, divergent and longer pubescence, as well as its shorter leaves, with less and shorter leaflets, shorter peduncles, fewer flowers per cluster, banner longer but narrower and its larger seeds. Occurs in high elevations of mountains, similar to A. purpusii (northeastern Mexico) and A. micranthus (central and southern Mexico).

Specimens examined:— DURANGO: 23 October 2010, Maíz Gordo, Mpio. Puebo Nuevo, C. Vázquez R. 40a, N. B. Cabada A. ( CIIDIR; CFNL) .

Figures

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