Astragalus guatemalensis Hemsl., Biol. Centr.

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

35. Astragalus guatemalensis Hemsl., Biol. Centr. - Amer. Bot. 1: 266. 1880

Perennial. Stems 7–220 cm long, prostrate, rhizomatous, creeping, decumbent, or erect when 60 cm long, sometimes with red tints. Stipules 1.5–9 mm long, clasping, the lowest ones connate for almost the half of its length, ending in a bidentate sheath, the upper ones basally connate or semi-clasping, lanceolate, acuminate. Leaves 2.1–13 cm long, leaflets 11–37, not always opposite to each other, 2–26 mm long, oblong elliptic to obovate, truncate or retuse distally, sometimes mucronate, thin, bicolored, light-green abaxially, glabrate, scattered pubescent or densely pubescent all over or only in the midvein adaxially. Peduncles 3–26 cm long, thin, ascending or incurved; the racemes 0.5–5 cm long, flowers commonly 6–30. Flowers rose, lilac, purple or purple-blue, pale yellow, yellow-cream, occasionally yellowish, yellow-greenish or white with lilac tints, soon deflexed to ascending-horizontal; the calyx 3.2–7.8 × 2.2–3.5 mm, pubescent, regularly with black trichomes, rarely white, the tube 2.6–4 mm long, the teeth 0.6–4 mm long, subulate, triangular to widely triangular; the banner 8.5–12 × 4.4–7 mm, ovate, obovate to rhombic, retuse or almost so; the wings 8–10.5 × 1.6–2.8 mm, the claw 3.2–4.6 mm long, the blade 6.2–8 mm long, narrowly oblong; the keel 6.8–8.3 × 2.1–2.7 mm, the claw 3–4.6 mm long, the blade 3.6–4.7 mm long, semi-obovate, sharp. Pod stipitate (the stipe 1–5 mm long), 1.2–2.1 x 0.4–0.8 cm, oblong to elliptic, dorsoventrally compressed, ventrally carinate, dorsally openly sulcate, inflated, but no bladdery-shape but bulged, straight or semi-curved, very rarely triquetrous****, narrowed in both ends, the valves glabrate to minute strigose, the trichomes black, the valves papery, black or turning ochre with age, softly reticulate, septum complete, the pod thence bilocular or partial so, opening dorsally in its total length; ovules 10–20; seeds 1.7–2.5 mm long, brown.

Distribution:— Central and southern Mexico, from northern Hidalgo and central Jalisco, through Michoacán, Estado de Mexico, Morelos, Guerrero, southern Puebla, Oaxaca to central Chiapas.

Comments:— Astragalus guatemalensis has a wide distribution in the mountains of southern Mexico. At least 11 other species with clasping and connate stipules, linear, elliptic, oblong, obovate, or bulged, but never triquetrous pods inhabit these areas. Several species in the region have stipitate pods such as A. jaliscensis , A. hintonii , A. strigulosus and A. tolucanus . Astragalus strigulosus and A. guatemalensis have short calyces, 6 mm long or smaller. Astragalus strigulosus has erect stems and ochroleucous and immauclate flowers, and longer calyx teeth, 2.5–4.3 mm long (at least in areas where both species converge (Guerrero, Oaxaca, Puebla and Oaxaca, except for Hidalgo). In Hidalgo, A. strigulosus and A. guatemalensis var. lozani are sympatric, but they have different habitat preferences because, A. strigulosus predominates in sunny areas, while A. guatemalensis var. lozani prefers wet areas.

Three varieties recognized based on stem and calyx size, and pubescence type.

1. Stems up to 29 cm long; pubescence of short and appressed trichomes mixed with longer and straight ones; the stipe 3.5–5 mm long; locally distributed in Hidalgo ...................................................................................................... A. guatemalensis var. lozanii

- Stems 30 cm or longer; pubescence of short appresed trichomes only; the stipe shorter, 1–2.5 mm long; wider distribution .........2

2. Calyx 3.2–6 mm long; the teeth 0.6–2.5 mm long; Colima, Jalisco, Hidalgo, Guanjauato, Michoacán, Nayarit, Guerrero, Estado de Mexico, Morelos, Puebla, Guerrero and Oaxaca ..................................................................... A. guatemalensis var. brevidentatus

- Calyx 6.4–7.8 mm long; the teeth 2.8–4.5 mm long; Chiapas ................................................ A. guatemalensis var. guatemalensis