Astragalus gambelianus E. Sheld., Bull. Geol. Nat. Hist. Surv.

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

28. Astragalus gambelianus E. Sheld., Bull. Geol. Nat. Hist. Surv. 9: 21. 1894

Type:— USA, California, Catalina Island, T. Nuttall s.n. (holotype (base on Astragalus nigrescnes ): PH00005487 digital image!; isotype (as Holalobus nigrescens ): H00058844 digital image!).

Hesperastragalus gambellianus A. Heller , Muhlenbergia 2: 87. 1905.

Annual or perennial. Stems 5–30 cm long, erect, single or branched basally, the external ones incurved-ascending distally, pubescence pilose, the trichomes up to 0.7 mm long, ascending, incurved. Stipules 1–3 mm long, deltoid to lanceolate, clasping semi or completely so, not connate. Leaves 1–4 cm long, leaflets 7–15, 2–9 mm long, linear, oblanceolate, strongly retuse, rarely truncate, their margin sometimes purple, adaxially and abaxially pubescent. Peduncles 2–6 cm long, ascending; the racemes 0.3–2.7 cm long, flowers 4–15, very dense, constituing a compact capitulum when young, ascending when young, pendulous with age. Flowers whitish, violet or lilac, the veins or margins with blue tones; the calyx 1.7–2.5 × 1–1.5 mm, pilose, mostly with black trichomes, rarely white ones, the tube 1.1–1.7 mm long, campanulate, turbinate or ovoid-campanulate, the teeth 0.5–0.9 mm long, subulate to triangular; the banner commonly 2.5–3.3 × 1.5–2 mm, ovate, elliptic, spathulate, sometimes shallowly retuse; the wings 2.2–2.7 × 0.5–0.8 mm, the claw 0.8–2.2 mm long, the blade 1.5–1.9 mm long, widely oblongs; the keel 2.2–2.5 × 0.8–1.1 mm, claw 0.9–1.2 mm long, the blade, sub-quadrangulate or almost orbicular; Pod 2.8–4.2 × 2.4–3.6 mm, deflexed, sessile, widely ovate, rhombic to dosrsally semicircular, rounded to widely cuneate, slightly retuse basally, distally narrowed abruptly in a minute, conic beak, dorsally obcompressed, wide and openly sulcate, the lateral angles narrow, reticulate, incurvate, ventrally straight or somewhat concave, the valves thin, hirsute to strigose, green, the trichomes up to 0.4 mm long, extended o incurved, rarely appressed, becoming papery, ochre or brown, the septum complete, the pod two-celled, or almost so; ovules 2; seeds 1.8–2.6 mm long, oblong, pale to dark brown, sometimes purple speckled, smooth.

Distribution:— In Mexico, in the northwestern and central portions of Baja California (El Jaraguay, 10 km SW of Santa Ynés). Also, in California and Oregon ( USA) ( Fig. 8 ).

Habitat:— Sandy or clayey soils, open grasslands, chaparral, oak-pine forests, rare, 750 m.

Comments:— From all the Astragalus species distributed on the peninsula of Baja California, only A. didymocarpus and A. gambelianus have small, never larger than 4.2 mm long, two-seeded fruits. Both species can be distinguished by the arrangement of their flowers and fruit shape. Astragalus didym ocarpus has flowers and pods erect, the pods are bladder-like or subglobose, divided into two inflated, separated sacks.

Specimens examined:— BAJA CALIFORNIA:1882, Lower California, C.C.Parry s.n. ( CAS); 25February1973, Colonet Mesa, 0.5 mile north of Colonet, R. Moran 20288, J. L. Reveal ( SD); 19 April 1980, Valley floor, 7.0 km southwest of Ojos Negros , R. Moran 28261½ ( SD) .

Figures

FIGURE 8. Map showing the distribution of Astragalus francisquitensis, A. gambelianus, A. gentryi, and A. giganteus in Mexico.