Astragalus Geyeri

Commonly very slender, fugitive, erect or diffuse annuals, with slender or filiform taproot, rarely persisting into a second season, strigulose with straight, appressed hairs, the stems usually canescent, the herbage cinereous in youth becoming greenish in age, the leaflets glabrous or medially glabrescent above; stems 1-20 cm. long, in the first year solitary or 3, the lateral ones arising from the cotyledonary axils, either simple and erect or commonly branched or spurred at the first 2-4 nodes, the prostrate or incurved-ascending branches elongating and often longer than the main axis, in the rare biennial state several arising from the indurated but scarcely caudiciform crown of the first season, together forming low, densely leafy tufts; stipules thinly herbaceous or submembranous, deltoid, deltoid-acuminate, or the uppermost ones lanceolate, 1.5-4 mm. long, semiamplexicaul, often more thinly pubescent dorsally than the adjacent stem and thereby forming a greenish spot; leaves (1.5) 2—10 cm. long, all petioled, with 3—13 rather distant, linear-elliptic, -oblong, or broadly oblong-elliptic, obtuse or retuse, folded or flat leaflets 3-17 mm. long; peduncles incurved-ascending, 0.6-2.5 cm. long, usually filiform, the first commonly produced at about the third or fifth node and thence upward along the stem, the earliest often appearing subradical; racemes loosely 2-8-flowered, the flowers at first ascending, declined in age, the axis little elongating, 3-15 mm. long in fruit; bracts membranous, ovate or lanceolate, 0.7-2 mm. long; pedicels at anthesis 0.6-1 mm. long, in fruit arched outward, a little thickened, 0.8-1.5 mm. long, persistent; bracteoles 0-2, minute when present; calyx 2.7-3.8 mm. long, strigulose with white or some dark hairs, the disc 0.4-0.7 mm. deep, the campanulate tube 1.6-2.4 mm. long, 1.5-2 mm. in diameter, the subulate or lance-subulate teeth 0.7-1.5 mm. long; petals whitish with faintly lilac-tipped keel, the banner sometimes suffused or veined with pale lilac, rarely all purple with a white eye, then drying violet; banner recurved through ± 45 (rarely 80)°, ovate- or oval-cuneate, shallowly notched, 5.2-7.6 mm. long, 3-4.8 mm. wide; wings 4.6-6.5 mm. long, the claws 1.7-2.4 mm., the oblanceolate to narrowly obovate, obtuse or obscurely emarginate, straight or lunately incurved blades 3-4.9 mm. long, 1.3-2.1 mm. wide; keel 3.8-4.8 mm. long, the claws 1.8-2.3 mm., the half-obovate or -circular blades 2.1-2.9 mm. long, 1.4-1.6 mm. wide, strongly incurved through 100-120° to the obtuse, deltoid apex; anthers 0.2-0.35 (0.4) mm. long; pod spreading or loosely declined (often humistrate), sessile, lunately or very obliquely half-ovoid, bladdery-inflated, 1.5-2.4 cm. long, 6-10 (or when pressed apparently up to 13) mm. in diameter, cuneate at base, contracted distally into a deltoid or triangular-acuminate beak, the body a trifle laterally compressed and obscurely triquetrous with rounded faces and angles (or the ventral angle sometimes acute), the ventral suture straight or more commonly concave in profile, the dorsal one gibbous-convex, the thin, pale green, sometimes purple-cheeked, finely white-strigulose valves becoming papery, stramineous, delicately cross-reticulate, not or narrowly inflexed; dehiscence apical, after falling; ovules 7-18; seeds olive- or yellowish-brown, sometimes purple-dotted, smooth or nearly so, 2.2-3 mm. long.

Over the greater northern half of its range the Geyer milk-vetch is the only annual species of its genus. It flowers early in the year, producing its characteristic fruit within a few weeks of germination of the seed and consequently is easily recognized. The pod is more strongly oblique than in all other Inflati except A. pubentissimus, a much coarser, villosulous plant with larger flowers and lustrously long-hairy fruits. At the south end of its range the species has given rise to a strongly differentiated variety, distinguished as follows: