Astragalus arrectus A.Gray
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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(1): 1-596.
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Family
Fabaceae
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Scientific Name
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Type
"Kooskooskee River, coll. Geyer." [or fide Hook. in Lond. Jour. Bot. 6: 211. 1847, sub nomine A. leucophyllo T. & G. (non Willd.): "on layers of stiff, ferruginous clay-banks on the Trappe Mountain declivities; upper Kooskooskie. May (no. 378)."]— Holotyp
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Synonyms
Phaca arrecta (A.Gray) Piper, Tium arrectum (A.Gray) Rydb., Astragalus palousensis Piper, Astragalus arrectus var. palousensis (Piper) M.E.Jones
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Description
Species Description - Erect, rather robust, with a woody taproot and shortly forking or knotty root- crown, strigulose-pilosulous nearly throughout with fine, usually loosely ascending and incurved, or straight and appressed to subappressed hairs up to (0.4) 0.5—0.75 mm. long, the herbage green or subcinereous, the leaflets glabrous above, the inflorescence more or less black-hairy; stems several or numerous, erect and stiffly ascending in clumps, stout, striate, 2-4 dm. long, composed of some 4-6 developed internodes, that preceding the first peduncle usually much the longest and up to 9-20 cm. long, the main axis abruptly inhibited beyond the second (or third) peduncle and usually forming less than half the height of the mature plant; stipules membranous becoming papery-scarious, 4-8 mm. long, the lowest ovate, obtuse, the upper ones lanceolate or triangular-acuminate, all rather strongly adnate to the petiole-base, decurrent around half, or the lowest more than half the stems circumference, the margins beset with a few minute tack-shaped processes; leaves (6) 9-22 cm. long, the upper cauline ones very shortly petioled, with (17) linear-oblong, narrowly oblong-elliptic, lanceolate or (rarely, only in some lower leaves) oval, obtuse, truncate, or deeply notched, nearly flat, rather scattered leaflets (3) 8-22 mm. long; peduncles stiffly erect, stout, striate, often appearing as a continuation of the stem, 1-2.5 (3) dm. long, greatly surpassing the leaves; racemes 15-33-flowered, at early anthesis rather dense but early loosening, the flowers ascending, the axis becoming 8-22 cm. long in fruit; bracts submembranous, triangular-lanceolate, 1.7-2.5 mm. long; pedicels straight, ascending, at anthesis 0.5-1.2 mm. long, in fruit clavately thickened, 1.5-3 (4) mm. long; calyx 5-6.3 mm. long, loosely strigulose or pilosulous with black, fuscous, or sometimes a few intermingled white hairs, the subsymmetric disc 0.7-1.2 mm. deep, the campanulate tube 3.7-4.7 mm. long, 3.1-4 mm. in diameter, the triangular-subulate teeth 1.3-1.8 mm. long, the ventral pair shorter and broader than the rest, the orifice somewhat oblique; petals ochroleucous, drying yellowish; banner ovate-cuneate, shallowly notched, 10-10.7 mm. long, 6.1-8 mm. wide; wings 12.3-13 mm. long, the claws 5.1-6.1 mm., the oblanceolate or obovate, obtuse, nearly straight blades 7.6-8.1 mm. long, 2.6-3.2 mm. wide; keel 10.1-10.6 mm. long, the claws 5.5-5.9 mm., the obliquely triangular blades 5.1-5.4 mm. long, 2.5-3.2 mm. wide, abruptly incurved through 90-95° to the bluntly deltoid apex; anthers 0.55-0.7 mm. long; pod erect, stipitate, the straight stipe (2.5) 3-6 mm. long, the narrowly oblong-ellipsoid body (1.5) 1.7-2.3 cm. long, 4.5-6.3 mm. in diameter, straight or a trifle in- or decurved, cuneate to broadly rounded at base, abruptly contracted distally into a short, triangular-acuminate, laterally compressed, rigidly cuspidate beak, otherwise obcompressed, the low-convex or nearly flat ventral face carinate by the prominent, thick suture, the dorsal face openly but deeply grooved, the lateral angles rounded, the more or less fleshy, green valves becoming brownish- stramineous, stiffly leathery, rugulose-reticulate, loosely strigulose or pilosulous with straight and subappressed, or sometimes incumbent and subsinuous, black, white, or mixed hairs up to 0.3-0.5 mm. long, inflexed as a narrow but often nearly complete septum 0.5-0.9 mm. wide; ovules 18-26; seeds (seldom seen) brown or black, apparently smooth but dull, ± 2.2 mm. long.
Distribution and Ecology - Grassy hillsides, sagebrush slopes and river bluffs, sometimes in openings of yellow pine forest, 1300—2600 feet, local but locally common in the rolling hill country about the lower Snake, Clearwater, and Palouse Rivers in Latah and Nez Perce Counties, Idaho, and Whitman County, Washington; also, perhaps disjunctly, along the lower Spokane and adjoining Columbia Rivers in the Grand Coulee region of Lincoln County, Washington.—Map No. 63.—Mid-April to July, the fruit long persisting.
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Discussion
The Palouse milk-vetch, A. arrectus, is most easily recognized by its irregularly proportioned flowers which ascend from the raceme-axis at an angle of about 45° and are followed by erect, stipitate, dorsally grooved pods of thick texture, pubescent with black or fuscous, rarely white hairs. The pod resembles that of A. Leibergi in shape and leathery texture, but the latter species has nodding flowers, regularly graduated petals, and the connately sheathing stipules of sect. Conjuncti. The common fate of A. arrectus has been confusion with A. atropubescens (Jones, 1923, p. 161, in part, Pl. 37, where the two entities are clearly distinguished but under the wrong names; Rydberg, 1929 p. 391 & 1931, p. 401). The pod of A. atropubescens is similar in form but of somewhat narrower and more slender profile, of thinner texture, and only rarely and then minutely strigulose. The species differs further from A. arrectus in its nodding flowers with wings intermediate in length between the banner and keel; and except for some isolated stations in the Grand Canyon of the Snake and the lower Salmon Rivers, its range of dispersal lies well to the east of A. arrectus at elevations mostly above 4000 feet. At the time of my revision of this immediate group (1956, p. 491) I had not seen authentic material of A. arrectus; but relying on Hooker’s description of the pod of Geyer 378 as glabrous and the indication of a type-locality on the upper Clearwater River, I tentatively but mistakenly assigned the epithet arrectus to A. atropubescens.
The main range of A. arrectus is far from extensive, reaching only from the confluence of Lolo Creek with the Clearwater River in Idaho northwest to the neighborhood of Colfax in Whitman County, Washington, a distance of some 65 miles. The known stations in the Columbia Valley in Lincoln County lie farther distant over one hundred miles and no intermediate stations are yet on record.
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Objects
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Distribution
Washington United States of America North America| Idaho United States of America North America|