Astragalus oxyphysopsis Barneby, Brittonia 1976

Field: Agricultural and Biological Sciences (Life Sciences)

64. Astragalus oxyphysopsis Barneby, Brittonia 28: 273. 1976 Type:— MEXICO, Baja California, locally common on ridge top, in clay soil of “dry bog,” 2500 ft (• 750 m), between San Telmo and Rancho Meling, in W foothills of Sierra San Pedro Mártir near, E. R. Blakley 7158, 16 Mar 1973, (holotype: SD 87953!; isotype: NY00005819!). Perennial. Stems villous, erect, suberect or somewhat decumbent, dense to softly pubescent, the trichomes up to 0.5 mm long, erect. Stipules 4–6.7 mm long, embracing only a third or less than stems circumference, semi-clasping, decurrent, not connate, triangular to wide-lanceolate. Leaves 5–11 cm long, leaflets 21–29, 4–15 mm long, oblong, elliptic to obovate, truncate to retuse apically, bicolored, adaxially clearer and less densely pubescent. Peduncles 10–19 cm long, erect, rarely sub-recurved; the racemes 5–13 cm long, flowers 30–45. Flowers whitish, immaculate, turning ochroleucous when drying; the calyx 6.6–7.6 × 3.8–4.4 mm, strigose, the tube 4.9–5.7 mm long; banner 13.3– 14 × 7.2–8 mm, recurved, rhombic to oblanceolate; the wings 13–13.4 × 2.3–2.6 mm, the claw 5.6–6 mm long, the blade 5.3–5.5 mm long, oblanceolate; the keel 11.4–11.5 × 2.5–2.8 mm, the claw 5.5–6 mm long, the blade 5.2–5.5 mm long, incurved, semi-obovate. Pod 2–3.1 × 0.8–1.3 cm, deflexed, stipitate (stipe 7.5–16 mm long) oblique-elliptic or sometimes rhombic, inflated, bladder-like, but strongly compressed laterally (in the form of a traditional flying saucer), ventrally evidently carinate, the valves stiff-papery to somewhat leathery, semi-transluscent, pale green when young, turning ochre with age, smoothly reticulate, septum absent; ovules 14–15; seeds 3–3.7 mm long, green olive, opaque. Distribution:— Endemic to Mexico, exclusively in Baja California, along road to San Pedro Mártir, westside of Sierra San Pedro Mártir and adjacent areas, San Telmo (31°04N – 115°51’W), Potrero, Meiling Ranch, El Jonuco, San Rafael and Mina Santa Cruz to El Canuto (30°20’N – 115°32’W) (Fig. 20). Habitat:— Black soils; river banks; associated with chaparral; 475–750 m. Comments:— Of all the species of Astragalus found in the Peninsula of Baja California, only two species, A. oxyphyospsis and A. oxyphysus have inflated bladder-like and laterally strongly flattened pods. Their populations are separated by approximately 110 km, A. oxyphysus, recorded for Ojos Negros (31°55’N, 116°18’W), they can be differentiated by subtle characteristics of the pod, in A. oxyphysopsis the pod is continuous with its stipe (non-articulated) and glabrous, whereas in A. oxyphysus the pod is raised from the receptacle by an pubescent, articulate gynophore. Astragalus oxyphysopsis is sympatric in elevation at San Telmo (30°58’N – 116°06’W) and morphologically similar to A. trichopodus var. lonchus, in growth habit, and leaf size, and stipitate pod, however, both can be differentiated based on their pod shape, A. trichopodus var. lonchus, has inflated bladder-like pods that are never strongly flattened. Specimens examined:— BAJA CALIFORNIA: 16 March 1973, Ridge top, “dry bog” between San Telmo and Rancho Meling, Baja California. Alt. 2500 ft., E. E. Blakley 7158 (NY); 3 May 1976, Mesa el Barrial, ca. 3 miles west of Rancho San José (Meling), R. Moran 23093 (ENCB, MEXU, NY, SD, TEX-LL), 23095 (NY, SD, US); 3 May 1976, Mesa el Barrial, on ridge 4 miles west of Rancho San José, R. Moran 23095 (NY); 1 June 1976, Sierra San Pedro Mártir. 4 km NW of Buena Vista, R. Moran 23371 (NY, SD), 23377 (NY, SD), 23382 (NY, SD); Sierra San Pedro Mártir. 1 km NW of Santa Cruz Mine, 2 June 1963, Along arroyo near Rancho El Ciprés, R. F. Thorne 31956 (MEXU, NY); 19 March 2012, Suroeste de Santo Tomás y oeste de la autopista 1; al norte de Erendira y al noreste de Punta Cabras: justo al lado de Rancho Embarcadero Road al oeste de Nativo del Valle, J. Rebman 22693, S. Vanderplank, et al. (SD).