Astragalus inflexus Douglas ex Hook.
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Authors
Rupert C. Barneby
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Authority
Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(2): 597-1188.
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Family
Fabaceae
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Scientific Name
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Type
"On the barren sandy grounds of the Columbia, from the junction of Lewis and Clarke’s River to the mountains. Douglas." -Holotypus, K! isotypi, BM, P!
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Synonyms
Tragacantha inflexa (Douglas) Kuntze, Phaca inflexa (Douglas) Piper, Xylophacos inflexus (Douglas ex Hook.) Rydb.
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Description
Species Description - Caulescent, diffuse, with a taproot and an ultimately branched but hardly woody caudex, densely villous or villous-tomentose, rarely pannose-tomentose throughout or nearly so with extremely fine, variously proportioned shorter, curly and entangled hairs together with longer, straighter, loosely ascending or spreading ones up to 1.3-2 (2.5) mm. long, the herbage greenish-gray or white-woolly; stems several, prostrate and radiating, or with incurved-ascending tips, mostly 13.5 (5) dm. (in occasional young or starveling individuals only 0.5 dm.) long, simple or bearing a few short branches or spurs below the middle, zigzag distally, almost always composed of several, often of many well-developed internodes up to 2-6 cm. long, together forming loose, leafy mats; stipules submembranous, ovate-, triangular-, or lance-acuminate or -caudate, 5-12 (16) mm. long, semi- amplexicaul-decurrent; leaves (3) 4-12 (16) cm. long, the lowest petioled, the upper ones very shortly so or subsessile, with 17-23 (27), or in some lower leaves as few as 9, obovate-cuneate, rhombic-oval, or broadly oblanceolate, acute, subacute, or shortly acuminate, rarely subobtuse, flat or loosely folded leaflets (4) 6-16 (20) mm. long; peduncles divaricate or incurved-ascending, (2) 3-8 cm. long, shorter or sometimes a trifle longer than the leaf, not recurved in fruit; racemes loosely (5) 8-18-flowered, the axis somewhat elongating, (1.5) 2.5-6 (8) cm. long in fruit; bracts submembranous, lanceolate or lance-acuminate, 4.510 mm. long; pedicels ascending, straight or nearly so, at anthesis slender, (1.3) 1.8-2.8 mm., in fruit thickened, 2-3.3 mm. long; bracteoles 0; calyx (9.4) 11.3 16.4 mm. long, usually purplish, villous with white or rarely some black hairs, the somewhat oblique, campanulate or funnelform disc 1.2—2.1 mm. deep, the cylindric or rarely cylindro-campanulate tube (6.2) 8.2-10.2 mm. long, 3.7-5.2 mm. in diameter, the linear-lanceolate or lance-caudate teeth 3.1-6.6 (7) mm. long; petals pink-purple, the banner with a pale, striate lozenge in the fold; banner recurved through ± 40°, oblanceolate, rhombic-oblanceolate, or -obovate, (16.5) 19.5-23 mm. long, 8.4-11 (14.5) mm. wide; wings (14) 18.2-20.2 mm. long, the claws (8) 9-11.8 mm., the oblong-elliptic or lance-oblong, obtuse or rarely obliquely emarginate, nearly straight blades (6.7) 8.2-11.2 mm. long, 2.2-3.2 (3.9) mm. wide; keel (12.7) 14.4-17.2 mm. long, the claws (8.2) 8.5-11.7 mm., the lunately elliptic or half-obovate blades (5.2) 5.9-6.8 mm. long, (2) 2.5-3.3 mm. wide, rather abruptly incurved through 90-100° to the blunt apex; anthers 0.55-0.65 mm. long; pod ascending or strongly incurved-ascending, sessile on an obscure gynophore (0.5) 0.7-1.8 mm. long, obliquely ovoid, lance-ovoid, or oblong-ellipsoid, (1.3) 1.5-2.5 (3) cm. long, (5) 7-9.5 mm. in diameter, obtuse or obtusely cuneate at base, in the lower ½-? straight or nearly so, obcompressed, and openly sulcate at least ventrally and commonly also dorsally, thence ± abruptly tapering and incurved through ± 90° into the broadly deltoid- to narrowly triangular-acuminate, laterally compressed beak, the somewhat fleshy, green valves becoming stiffly leathery, stramineous or brownish, reticulate, villous-hirsute or exceptionally tomentose with variably proportioned shorter, curly hairs and longer, ascending or spreading, straighter ones up to (1) 1.3-2.2 mm. long, the shaggy vesture rarely concealing the whole surface and never the shape of the fruit, the valves not inflexed, but the sutures approximate or contiguous within, the cross-section deeply cordate or subdidymous; dehiscence apical, through the gaping beak; ovules 22-28 (33); seeds ocher-, olive-, or mahogany-brown, sometimes almost black, smooth or very sparsely pitted, dull, 1.7-2.8 mm. long.
Distribution and Ecology - Open grassy hillsides, dry pastures, valley floors, and river terraces, in light dry alluvial soils derived from basalt or granite bedrock, rarely in yellow pine forest, (600) 1100—4200 feet, locally abundant but apparently of discontinuous distribution: most frequent along the lower Snake, Salmon, Clearwater, and Palouse Rivers and their tributary streams in southeastern Washington, northeastern Oregon, and westcentral Idaho, extending in Washington feebly downstream along the Snake River to its confluence with the Columbia and north into Spokane County; western Montana, west of the Continental Divide, from Flathead Lake south to the Bitterroot Valley; upper Missouri Valley, Montana, from near the mouth of the Belt River upstream to the lower Madison River—Map. No. 89.—May to early July.
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Discussion
Prominent features of the bent milk-vetch, A. inflexus, other than the cottony vesture common to the Eriocarpi, are the well-developed, distally flexuous stems, the subsessile upper leaves composed of relatively numerous (mostly 17-23) leaflets, the racemes of some dozen or more flowers, and the long, often caudate-acuminate stipules echoed in the inflorescence by long bracts and calyx-teeth. No single one of these characters is consistently diagnostic of the species; but in practice there is scarcely ever any doubt as to its identity, except in rare cases of plants collected in early flower, or for some reason depauperate. Some of these have been mistaken for A. Purshii var. glareosus, and Jones speaks (1923, p. 221) of "puzzling intergrades" between A. inflexus and var. glareosus found "above the great bend of the Snake River at Huntingdon (i.e., upstream from the Baker-Malheur County line in Oregon and in adjacent Idaho). Plentiful material from this area is now available, all of it, with the exception of one record (north of Weiser, Sharpe 17,189, NY) of typical A. inflexus, to be referred to var. glareosus sens. strict. The ranges of these two astragali overlap elsewhere only along the Columbia River near the Great Bend in Washington, and here A. inflexus is confined to the immediate banks of the river and is probably a recent immigrant by way of seeds brought down by the flood waters of the Snake. Over most of its range A. inflexus is the only member of its group with purple flowers.
A superficially remarkable form of the bent milk-vetch, but probably no more than a minor variant, is known from a thriving, apparently uniform population established on a dune of river sand in the bed of the Salmon River canyon north of Riggins, Idaho (Ripley & Barneby 10,728). The plants differ from normal hirsute or both hirsute and tomentulose A. inflexus in being cottony-pannose throughout, the vesture (which resembles that of A. utahensis in quality) extending even to the pods. More material from the Salmon canyon is needed.
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Objects
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Distribution
Idaho United States of America North America| Oregon United States of America North America| Washington United States of America North America| Montana United States of America North America|