Astragalus magdalenae Greene, Pittonia, 1888

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

55. Astragalus magdalenae Greene, Pittonia 1(4): 162. 1888

Perennial. Stems silver or lead color, silky, up to 70 cm long, decumbent or ascendant, strigose or villous, the trichomes up to 0.9 mm long, dense, similar or some longer, soft, appressed to sub-appressed. Stipules 1–5.7 mm long, clasping or surrounding only a third o almost half of the stem circumference, triangular to deltoid, dorsally pubescent. Leaves 1–15 cm long; leaflets 3–23, 1.5–14 mm long, with similar color and pubescence on both faces. Peduncles 2–15 cm long, erect or incurved, the trichomes white, sometimes black; the racemes 2.5–6.5 cm long, compact or lax with age, or soon lax; flowers 10–37. Flowers variously colored, rose-purple, red-violet, lavender, white only some petals or white in different parts, rose-lavender, turning blue when drying, the banner maculate in the central fold; the calyx 4.1–9.4 × 2.4–3.8 mm, silky, the trichomes white and black, the tube 2.8–4.1 mm long, campanulate, the teeth 1.2–5.2 mm long, linear to triangular; the banner 9.4–14.4 × 6.2–10.5 mm, ovate, elliptic, rhombic to obovate, recurved; the wings 8–13.5 × 2–4 mm, the claw 3–4.4 mm long, the blade 5–10.3 mm long, oblanceolate to narrow-elliptic, somewhat straight or slightly incurved; the keel 7–10.1 × 2.5–3.6 mm, the claw 3–4.3 mm long, the blade 4.7–6.7 mm long, semi-obovate. Pod sessile, spreading, 1–3.7 × 1–2.3 cm, ovoid, elliptic to subglobose, inflated bladder-like, basally rounded or turbinated distally, apically contracted in a short triangular beak, ventrally slightly sulcate, dorsally sulcate, somewhat gibous or little convex, the valves light-green, green-tan, ochre or with purple tones, strigose, papery, semi-transparent, softly reticulate, septum absent; ovules 12–30; seeds 1.6–5.5 mm long, mitten shaped, brown or with purple tones, pitted, opaque.

Distribution:— In Mexico, exclusive to coastal dunes of Baja California, Baja California Sur, and Sonora. In Sonora from 31°30’N – 114°09’W (near 37 km ESE of Golfo de Santa Clara, through Puerto Peñasco, Álvaro Obregón, Puerto Lobos, El Julio, Campo Julio, Puerto Libertad to Desemboque de los Seris (29°30’N – 112 ° 20’W). In Baja California, along the entire western coast, in the central portion, isolated between Mission Santa María (30°24’N – 115°52’W) and Nueva Odisea (30°22’N – 115°52’W), on the geopolitical boundary of Baja California and Baja California Sur, from Puerto Venustiano Carranza (28°09’N – 113°53’W) and Guerrero Negro, through Campo Queen, San Pablo, San Roque, Asunción Bay, Punta Abrojos, around San Ignacio Lagoon (26°51N – 113°07’W), from there to San Carlos, Puerto San Carlos (29°46’N – 114°24’W) to Calamajué (29°38’N- 114-05’W), along the eastern coast, from Molino (29°46’N –114°24’08’W). In Baja California Sur, along the same eastern coast, registered only in San Antonio (26°32’N – 111°30’W).

Comments:— The coastal dunes on the Peninsula of Baja California harbor several species of Astragalus with sessile inflated pods that resemble A. magdalenae , several obvious and contrasting characters allows differentiation of them. Astragalus pomonensis differs by its green-whitish or ochroleucous petals. Astragalus insularis has smaller petals (banner 5.5–7.4 mm, wings 5–6.5 mm long, the keel 4.8–6 mm); A. harbisonii has connate stipules (at least the lowest ones). Astragalus hornii var. minutiflorus has strong similarities in the coloration of the foliage, their physiognomy is easily confused with any other ashy colored foliage, but, A. hornii var. minutiflorus can be distinguished by its inflorescences arranged in compact or oblong racemes; relatively short wings (7–9.8 mm) and relatively and proportionally smaller fruit (9–17 mm long), inhabiting in alkaline soils and cemented terraces, never properly restricted to coastal dunes as A. magdalenae .

Three varieties recognized, based on leaflet number and pod size. The flower color of var. magdalenae and var. niveus varieties present different tones, in both, the same colors are reported in the different petals, so it was considered not to include this characteristic in the keys.

1. Leaflets 3–13; terminal leaflet narrow, longer and of different form than the pair of terminal leaflets; Sonora ........... var. peirsonii

- Leaflets 15–23; terminal leaflet wide, of equal size and shape that distal pair and the rest of leaflets .............................................2

2. Banner 9.4–11 mm long; pod 1.5–2.6 cm long; ovules 16–20; seeds 1.6–2.5 mm long; Peninsula of Baja California and Sonora ... .................................................................................................................................................................................. var. magdalenae

- Banner 11–12.5 mm long; pod 1–2 cm long; ovules 12–14; seeds 2.5–3.3 mm long; Peninsula of Baja California and Sonora ....... ............................................................................................................................................................................................ var. niveus