Astragalus longissimus

Title

Astragalus longissimus

Authors

Rupert C. Barneby

Scientific Name

Astragalus longissimus (M.E.Jones) Barneby

Description

30.  Astragalus longissimus

Perennial from a woody taproot and knotty root-crown or shortly forked caudex at or just below soil-level, pilosulous with fine, subappressed and narrowly ascending, straight or nearly straight hairs up to 0.6-1 mm. long, the herbage green or subcinereous, the leaflets glabrous, medially glabrescent, or strigulose above; stems few, rather stout, erect or strictly ascending, (1.5) 2-4 dm. long, simple or branched or spurred at 1-3 nodes preceding the first peduncle, floriferous upward from near or shortly above the middle; stipules 1.5-8 mm. long, dimorphic, the small lower ones amplexicaul and connate into a papery, bidentate sheath, becoming fragile and sometimes deciduous in age, the upper ones herbaceous, lanceolate, very shortly or obscurely connate or free; leaves 5.5-15 cm. long, subsessile or the lowest shortly petioled, with 25-39 (45) oblanceolate to narrowly obovate, elliptic, or linear-elliptic, obtuse or mucronulate, mostly flat leaflets (1) 3-14 mm., long; peduncles erect or incurved-ascending, 5-21 cm. long, the first 1-3 usually stout, the later ones slender, equaling or longer than the leaf; racemes loosely or remotely (12) 20-45 (75)-flowered, the flowers early reflexed, the axis elongating, (4) 6-15 (30) cm. long in fruit; bracts linear-lanceolate, 1.5-3 mm. long; pedicels at anthesis 1-2 mm. long, becoming recurved, abruptly deflexed, or straight and declined or divaricate, somewhat thickened, 2-4 mm. long in fruit, persistent; bracteoles 0; calyx 3.2-5 mm. long, densely strigose-pilosulous with white, fuscous, black, or mixed light and dark hairs, the somewhat oblique disc 0.7-1 mm. deep, the tube 2.4-3.5 mm. long, 2.1-3 mm. in diameter, the subulate or triangular- subulate teeth 0.8-1.5 mm. long, the ventral pair sometimes shortest and broadest, the whole becoming papery, marcescent unruptured; petals ochroleucous, drying dull yellow; banner recurved through ± 50° or further in withering, ovate-cuneate, shallowly notched, 5.3—8.3 mm. long, 3.2—5.5 mm. wide; wings (0.1—1 mm. longer) 5.4-8.5 mm. long, the claws 2-3.5 mm., the obovate or narrowly oblong, obtuse or truncate-emarginate blades 3.7—5.5 mm. long, 1.5—2.5 mm. wide, both incurved but the left one more abruptly so from its junction with the claw; keel 6.6 mm. long, the claws 2.1—2.8 mm., the half-obovate or -orbicular blades 2.8-4 mm. long, 1.7-2.5 mm. wide, incurved through 95-105° to the deltoid, often subporrect apex; anthers 0.4—0.5 mm. long; pod pendulous, stipitate, the straight stipe 3—5.5 mm. long, the body narrowly lance-oblong, oblong, or oblong- elliptic in profile, straight or very slightly decurved, 1.4—2.3 cm. long, 4-5 mm. in diameter, cuneate at both ends, obcompressed-triquetrous, carinate ventrally by the prominent thick suture, openly and shallowly sulcate dorsally, the lateral faces low-convex, the lateral angles obtuse, the green, scarcely fleshy valves becoming stramineous, rather stiffly papery, faintly reticulate, inflexed as a partial or sub- complete septum 0.7—1.3 mm. wide; ovules 10—20; seeds pale or purplish-brown, pitted and sometimes prismatically angled, scarcely lustrous, 2-2.5 mm. long.— Collections: 8 (o); representative: E. W. Nelson 6174 (NY, US), 6283 (NY); Jones (from Mound Valley) in 1903 (NY, POM, US).