Monographs Details: Astragalus villosus Michx.
Authors:Rupert C. Barneby
Authority: Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(2): 597-1188.
Family:Fabaceae
Discussion:

304.  Astragalus villosus

Slender, diffuse, caulescent, perennial but of short duration, sometimes flowering the first season, with a shortly penetrating, often branching taproot and at length loosely forking caudex or knotty root-crown usually buried in litter (perhaps sometimes shortly subterranean), the herbage green, but the upper internodes, the leaf-rachises, the lower leaf-surfaces, and the peduncles hirsute with fine, spreading and ascending, often spirally twisted hairs up to 1.1-2 mm. long, the inflorescence silvery-pilose; stems few or several, decumbent or prostrate, 2-15 cm. long, leafless for a space of 0-7 cm., simple or shortly spurred at the lowest leafy axils, together forming loosely woven mats or depressed tufts; stipules herbaceous, or the lowest becoming papery-membraneous, broadly ovate, ovate- acuminate, or lanceolate, (1) 2-8.5 mm. long, decurrent around ½-? the stem’s circumference, the lowest rarely fully amplexicaul and even shortly united, all glabrous or nearly so dorsally, hirsute-ciliate, the margins sometimes beset with a few minute tack-shaped processes; leaves (1.5) 3-10 (12) cm. long, slender- petioled, with 7-15 (or in some early leaves, or in some juvenile plants, only 3-7) obovate, broadly oblanceolate, or suborbicular, mostly retuse-emarginate, sometimes truncate, flat, thin-textured, often visibly penninerved leaflets (2) 5-22 mm. long, the terminal one usually larger than the last pair; peduncles slender, (2) 3-11 cm. long, incurved-ascending at anthesis, procumbent in fruit; racemes (5) 8-24-flowered, rather dense at early anthesis, the flowers ultimately horizontal or declined, the axis little elongating, 1-3 (4) cm. long in fruit; bracts herbaceous, lanceolate or linear-lanceolate, (2) 2.5-5 mm. long, long-ciliate, deflexed in fruit; pedicels at first ascending and then arched outward, at anthesis 0.7-1.5 mm., in fruit either ascending or divaricate, a little thickened, up to 2.5 mm. long, persistent; bracteoles 0; calyx 5.5—7.8 (8.2) mm. long, ascending-hirsute, the scarcely oblique disc (0.5) 0.8-1.3 mm. deep, the campanulate, submembranous, often purplish tube 2.7-3.7 (4) mm. long, 2.5-3.3 mm. in diameter, the firm, lanceolate, triangular-lanceolate, or lance-attenuate teeth (2.7) 3—4.5 (5) mm. long, the whole a trifle accrescent, in fruit papery, marcescent usually unruptured; petals pale yellow or greenish-ochroleucous, immaculate; banner recurved through 50-80°, ovate cuneate, notched, 8.8-11.2 mm. long, 5-7 mm. wide; wings (as long or a trifle longer) 8.8-11.5 mm. long, the claws 2.6-3.4 mm., the broadly oblanceolate, elliptic, or obliquely triangular, obtuse or sometimes subacute or obliquely emarginate blades 6.7-8.5 mm. long, 2.5-3.3 mm. wide, the left one more strongly in curved than the right and its inner margin infolded; keel 12-9.1 mm. long, the claws 2.8-4.2 mm., the lunately half-elliptic blades 4.6-5.8 mm. long, 2.2-3.5 mm. wide, incurved through 80—110° to the narrowly deltoid, acute or subacute, often slightly porrect apex; anthers 0.45—0.6 (0.65) mm. long; pod spreading or ascending (humistrate, sometimes appearing declined in pressed spms.), sessile on the conical receptacle, or elevated on a stout, glabrous gynophore up to 0.8 mm. long, slenderly lunate- or half-ellipsoid, (1.5) 1.7-2.4 cm. long, (2.8) 3.2-5.2 mm. in diameter, gently incurved or nearly straight, broadly or narrowly cuneate at base, tapering distally into a lance-subulate, slightly declined beak ± 3-5 mm. long, bluntly triquetrous, keeled ventrally by the suture, openly and shallowly sulcate dorsally, the thinly fleshy, pale green valves hirsute with lustrous, spreading-ascending hairs up to 1.2—1.8 mm. long, becoming stramineous and ultimately brownish, stiffly papery, prominently reticulate, inflexed as a rudimentary septum up to 0.3 mm. wide; dehiscence tardy, apical and downward through the ventral suture; ovules 12-18; seeds brown, sometimes purple-speckled, 1.7-2.2 mm. long.—Collections: 34 (iii); representative: Curtiss 601 (NY, SMU); Small & al. 11,175, 11,195 (NY); Godfrey 52,919 (NY); Ripley & Barneby 10,134 (CAS, RSA).

Glades, savannas, openings in sandy pine woods, sometimes along roadsides, scattered but locally plentiful, southern South Carolina through central Georgia to southwestern Alabama and western and northcentral Florida; reported from Tennessee (Mell in Bull. Ala. Agric. Exp. Sta. No. 70. 284).—Map No. 138.— Late February to May.

Astragalus villosus (softly hairy) Mchx., Fl. Bor.-Amer. 2: 67. 1803.—"Hab. in Georgia."—Holotypus, P (herb. Mchx.)!—Phaca villosa (Mchx.) Nutt., Gen. 2: 97. 1818. Tragacantha villosa (Mchx.) O. Kze., Rev. Gen. 949. 1891. A. intonsus (unshaven) Sheld. in Minn. Bot. Stud. 1: 23. 1894, a superfluous substitute, the supposed obstacle, A. villosus Gueldenst., Reise Russl. 2: 187. 1791, being a nom. nud.—Tium intonsum (Sheld.) Rydb. ap. Small, Fl. S. E. U. S. 1332. 1903. Batidophaca villosa (Mchx.) Rydb. in N. Amer. Fl. 24: 319. 1929.

The bearded milk-vetch, A. villosus, is a lowly but delightful little astragalus, notable for the few leaflets of membranous texture, bright green beneath the sparse but long and lustrous pubescence, for the rather small, primrose-yellow or greenish-creamy flowers, and for the narrowly ellipsoid, often shallowly crescentic, handsomely hirsute pods. In Georgia it is sometimes associated with the tall, erect A. Michauxii, in western Florida with the more nearly related and habitally similar A. obcordatus, but both of these have almost glabrous foliage, lilac or purple-tinged petals, and hairless ovary and pod. The leaflets of young plants, which often flower during the first year of growth, are ordinarily only 3-7 in number and comparatively ample, but these give place the following season to leaves composed of 7-15 leaflets, of which the terminal one is commonly much the largest. The taproot of A. villosus is unusually slender for a perennial astragalus and is sometimes several times forked, at the same time giving rise to many lateral rootlets. It makes the nearest approach to a fibrous root-system known in the American species of the genus.