Astragalus Castetteri

Title

Astragalus Castetteri

Authors

Rupert C. Barneby

Scientific Name

Astragalus castetteri Barneby

Description

48. Astragalus Castetteri

Caulescent perennial with a woody taproot and shallowly buried root-crown or caudex, strigulose nearly throughout with fine, straight, appressed hairs up to 0.3-0.45 mm. long, the herbage green or cinereous when young, the leaflets more or less bicolored, brighter green but either glabrous or thinly pubescent above; stems several or numerous, diffuse and incurved-ascending, 2—4 dm. long, leafless and subterranean for a space of 1—12 cm., spurred or shortly branched at 1—5 nodes preceding the first peduncle, floriferous upward from near or a little below the middle; stipules 2—7 mm. long, strongly dimorphic, the lowest ones amplexicaul and connate into a papery, pallid or brownish, subtruncate or obtusely bidentate, eventually glabrous and fragile sheath, the upper ones longer, herbaceous, deltoid-acuminate or lanceolate, amplexicaul but only very shortly or obscurely connate, strigulose dorsally, the blades mostly erect; leaves (3.5) 5—10 cm. long, petioled but the uppermost only shortly so, with (11) 13—25 oblong-elliptic or (in some lower leaves) obovate, emarginate, flat or loosely folded leaflets (2.5) 5-14 mm. long; peduncles rather stout, 4.5—8 cm. long, a little longer or shorter than the leaf; racemes 8—18-flowered, rather dense at early anthesis, the flowers early spreading and declined in age, the axis not greatly elongating, 2—5 cm. long in fruit; bracts submembranous, narrowly lance-acuminate, 2—4 mm. long; pedicels at anthesis slender, ascending, 0.8—1.5 mm. long, in fruit a little thickened, recurved, or straight and divaricate, 2-3.5 mm. long, tardily disjointing with the fruit; bracteoles 0; calyx 7.9—10 mm. long, loosely strigulose or villosulous with incurved and ascending, black or mixed black and white hairs, the strongly oblique disc 1.2-1.6 mm. deep, the deeply campanulate or subcylindric, subtumid, purple- tinged tube 5.8-7.2 mm. long, 3.5-4 mm. in diameter, the subulate teeth 2-3.5 mm. long, the whole becoming papery, marcescent; petals pale purple, drying dull lavender; banner recurved through 45°, broadly rhombic-oblanceolate or -spatulate, openly notched, 14-18.7 mm. long, 7.4-9 mm. wide; wings 14.2-17.6 mm. long, the claws 7-8.1 mm., the narrowly oblong-elliptic, obtuse, almost straight blades 8-10.2 mm. long, 2.4-2.8 mm. wide; keel 11-14.4 mm. long, the claws 6.2-7.8 mm., the half-obovate blades 5.2-7.6 mm. long, 2.8-3.1 mm. wide, abruptly incurved through 90° to the exactly or bluntly deltoid apex; anthers 0.650.75 mm. long; pod widely spreading or declined, stipitate, the stipe 1.5—3 mm. long set at an oblique angle to the subsymmetrically ovoid-acuminate or -ellipsoid, bladdery-inflated body, the body 2.2-2.8 cm. long, 1.1-1.6 cm. in diameter, cuneately contracted at base into the stipe, narrowed distally into a triangular-acuminate, laterally compressed, almost erect beak 4-8 mm. long, otherwise subterete but shallowly sulcate ventrally, the sutures both filiform, the thin, red-mottled, loosely strigulose or subvillosulous valves becoming papery, stramineous, subdiaphanous, somewhat lustrous, finely cross-reticulate, smooth within, not inflexed, the funicular flange 0.7 mm. wide; dehiscence apical, through the beak; ovules 22-26; seeds dark brown, minutely pitted or almost smooth, dull, 2.2-2.8 mm. long.— Collections: 3 (o); representative: Hershey 2007 (RM).