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Astragalus amphioxys var. vespertinus
Astragalus amphioxys A. Gray var. vespertinus (Sheldon) M.E. Jones
Aladdin's Slippers
Fabaceae (Pea family)
Synonym(s):
USDA Symbol: ASAMV
USDA Native Status: L48 (N)
"Low, tufted, or loosely matted, sub acaulescent or shortly caulescent, winter- annual or perennial of short duration, densely strigose-strigulose throughout with stiff, straight, appressed, usually subcontiguous (and on some peduncles and petioles a few narrowly ascending), sometimes mixed with shorter, sinuous hairs up to 0.65-1.25 (1.5) mm. long, the herbage silvery-white or rarely greenish, the leaflets equally pubescent on both sides, the inflorescence sometimes black- hairy; stems usually several, prostrate or weakly ascending, in seedlings sometimes solitary and erect, 1—7 (exceptionally, in shade, up to 15) cm. long, the internodes often concealed by stipules, but as commonly developed and up to 2 (4.5) cm. long but mostly less." (bibref: 1814).
"The crescent milk-vetch, A. amphioxys, is a perplexingly polymorphic species. The pod is highly variable in length, degree of curvature, and compression, although the mode of compression is determined to large degree by the other two. The species is adapted to desert or near-desert climates and the populations fluctuate greatly in number and vigor in response to bountiful or meager spring rainfall. The plants are potentially perennial but relatively shortlived, often bearing flowers and fruits precociously, and sometimes perishing after the first or second summer. A favorable season after a period of several years drought, during which the older plants have died out, may bring out a swarm of floriferous seedlings easily mistaken for annuals. In the Rio Grande Valley, where summer rainfall prevails, the crescent milk-vetch can often be found in flower from late June or July onward, although elsewhere it is essentially a member of the early spring flora." (bibref: 1814).
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Plant Characteristics
Duration: Annual , PerennialHabit: Herb
Leaf Arrangement: Alternate
Fruit Type: Legume
Size Notes: "Stems usually several, prostrate or weakly ascending, in seedlings sometimes solitary and erect, 1-7 (exceptionally, in shade, up to 15) cm. long." (bibref: 1814).
Leaf: "Stipules (1.5) 2.5-10 (13) mm. long, submembranous becoming papery in age, ovate, deltoid, triangular, triangular-acuminate or -caudate, semi- (the lowest sometimes fully) amplexicaul; leaves 2-10 (13) cm. long, all petioled, with (7) 11-21, or in some seedlings only (1) 3-7, elliptic, rhombic- elliptic, oblanceolate, or obovate, sharply acute to obtuse and mucronulate, exceptionally emarginate, distant or crowded, flat or loosely folded leaflets 3-13 (20) mm. long." (bibref: 1814).
Flower: "Peduncles ascending at anthesis, arcuate-recurved or prostrate in fruit, (1) 2.5-14 (20) cm. long, a little longer or shorter than the leaf; racemes loosely but often quite shortly (2) 4-10 (13)-flowered, the flowers ascending, the axis (0.5) 1-4.5 (6.5) cm. long in fruit; bracts submembranous becoming papery- scarious, narrowly ovate to lanceolate or lance-acuminate, 2.5-8 mm. long, pedicels ascending or arched outward in age, at anthesis slender, 0.6-1.8 mm., in fruit thickened, 1.2-2.5 mm. long; bracteoles 0-2; calyx 6.3-14.2 mm. long, pubescent like the herbage with white, mixed black and white, or all black hairs, the slightly oblique disc 1.2-2.7 (3) mm. deep, the cylindric or cylindro-campanulate, purplish tube 8.8-13.2 mm. long, 3.8-5.2 mm. in diameter, the subulate teeth 1.3-3 mm. long; petals bright pink-purple, the banner with a large striate lozenge in the fold, exceptionally pure white; banner recurved through about 40 degrees, oblanceolate, rhombic- oblanceolate, or spatulate, shallowly or deeply notched, 23-27 (28) mm. long, 7.8-12.7 mm. wide; wings 21.5-25 (26) mm. long, the blades 12.2-16.3 mm. long, 2.5-4.2 mm. wide, linear- or narrowly lance-oblong, usually a trifle dilated above the claw 10.2-13.4 mm, the distal half a little narrower and either straight or incurved, obtuse; keel 19-23.6 mm. long, the half-obovate or obliquely triangular- obovate blades 8.6-12.2 mm. long, 3.2-4.4 mm. wide, rather abruptly incurved through 85-95 degrees to the rounded apex; anthers 0.5-0.85 (0.9) mm. long." (bibref: 1814).
Fruit: "Pod ascending (humistrate), variable in length and curvature, about 3-3.5 cm. long, 5-10 mm. in diameter, gently incurved; both sutures prominent their whole length, the dorsal one often sinuous, commonly depressed at the middle of the pod and lying in a double groove, the green or sometimes mottled, more or less fleshy, strigulose valves becoming stiffly leathery or subligneous, rarely a trifle spongy in age, reticulate and sometimes also wrinkled lengthwise, often rugulose on the obtuse, transversely dilated angles, either not inflexed or if so the septum present only near the middle of the pod and very narrow, not over 1.1 mm. wide; dehicence apical, through the gaping beak, and also basal, through the dorsal or both sutures; ovules 50-70 (averaging about 60); seeds brown, variably pitted or wrinkled, sometimes lustrous, 2-2.9 mm. long." (bibref: 1814).
Bloom Information
Bloom Color: Pink , PurpleBloom Time: Apr , May , Jun
Bloom Notes: "Petals bright pink-purple, the banner with a large striate lozenge in the fold, exceptionally pure white." (bibref: 1814).
Distribution
USA: AZ , CO , NM , NV , UTNative Distribution: "Locally plentiful within the Colorado Basin, south of Tavaputs Escarpment, southwestern Colorado and southeastern Utah, extending feebly west to the Grand Canyon and Kanab Plateau in northwestern Arizona." (bibref: 1814).
Native Habitat: "Sandy valley floors, ledges under cliffs, and gravelly hillsides, in sagebrush or juniper forest, mostly on sandstone, 4300—5900 (6300) feet." (bibref: 1814).
Bibliography
Bibref 1814 - Atlas of North American Astragalus Volume 2 (1964) Barneby, Rupert C.Search More Titles in Bibliography
Additional resources
USDA: Find Astragalus amphioxys var. vespertinus in USDA PlantsFNA: Find Astragalus amphioxys var. vespertinus in the Flora of North America (if available)
Google: Search Google for Astragalus amphioxys var. vespertinus
Metadata
Record Modified: 2020-12-07Research By: Joseph A. Marcus