Native Plants
Plant Database
Search for native plants by scientific name, common name or family. If you are not sure what you are looking for, try the Combination Search or our Recommended Species lists.
Astragalus arrectus
Astragalus arrectus A. Gray
Palouse Milkvetch
Fabaceae (Pea family)
Synonym(s): Astragalus palousensis
USDA Symbol: ASAR7
USDA Native Status: L48 (N)
"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." (bibref: 1813).
"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 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." (bibref: 1813).
From the Image Gallery
No images of this plant
Plant Characteristics
Duration: PerennialHabit: Herb
Leaf Arrangement: Alternate
Fruit Type: Legume
Size Notes: "Stems... up to 9-20 cm. long." (bibref: 1813).
Leaf: "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." (bibref: 1813).
Flower: "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 degrees to the bluntly deltoid apex; anthers 0.55-0.7 mm. long." (bibref: 1813).
Fruit: "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, about 2.2 mm. long; the fruit long persisting." (bibref: 1813).
Bloom Information
Bloom Color: White , YellowBloom Time: Apr , May , Jun , Jul
Bloom Notes: "Petals ochroleucous, drying yellowish. Mid-April to July." (bibref: 1813).
Distribution
USA: ID , WANative Distribution: "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." (bibref: 1813).
Native Habitat: "Grassy hillsides, sagebrush slopes and river bluffs, sometimes in openings of yellow pine forest, 1300—2600 feet." (bibref: 1813).
Bibliography
Bibref 1813 - Atlas of North American Astragalus (1964) Barneby, Rupert C.Search More Titles in Bibliography
Additional resources
USDA: Find Astragalus arrectus in USDA PlantsFNA: Find Astragalus arrectus in the Flora of North America (if available)
Google: Search Google for Astragalus arrectus
Metadata
Record Modified: 2020-12-07Research By: Joseph A. Marcus