Astragalus toquimanus Barneby

Authors

Rupert C. Barneby

Authority

Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(1): 1-596.

Family

Fabaceae

Scientific Name

Astragalus toquimanus Barneby

Type

"Nevada: in a canyon of the Toquima Range about six miles east of Manhattan, Nye Co., alt. 7000 ft., 1 June 1941, fl. & fr., Ripley & Barneby No. 3692 ..." —Holotypus, CAS! isotypus, RSA!

Description

Species Description - Slender, wiry, strigulose nearly throughout with fine, appressed hairs up to 0.2-0.5 mm. long, the herbage greenish or cinereous when young, the leaflets sometimes glabrescent above in age; stems several or numerous, incurved-ascending from the shortly forking caudex, 7-25 (30) cm. long, simple, purplish at base, flexuous distally; stipules 1.5-3 mm. long, deltoid or triangular, firm, purplish, the lowest becoming papery and brownish, decurrent around ± 34 the stem’s circumference, the upper ones narrower; leaves (2.5) 4-11 cm. long, all petioled but the uppermost shortly so, with 9-17 oblong-oblanceolate or linear-oblong, or (in some lower leaves) obovate, obtuse or retuse, mostly folded and backwardly arched leaflets 3-15 mm. long; peduncles incurved-ascending, sometimes becoming divaricate and incurved, 2.5-6 (10) cm. long; racemes loosely 9-20- flowered, the flowers early spreading and then declined, the axis elongating, 4.5-13 cm. long, the fruits laxly secund; bracts membranous, purplish, ovate or lanceolate, 1-1.5 mm. long; pedicels at anthesis 0.5-0.8 mm. long, in fruit arched outward and 1-2 mm. long; bracteoles commonly 2, minute; calyx 3.5-4 mm. long, shortly black and white-strigulose, the disc 0.5-0.8 mm. deep, the tube 2.5-2.8 mm. long, 1.8-2.3 mm. in diameter, the broadly subulate teeth 1-1.5 mm. long, the whole becoming papery, marcescent unruptured; petals ochroleucous, veined and distally suffused with dull lilac; banner recurved through ± 90°, ovate-cuneate or sub- flabellate, notched, 6.9-7.6 mm. long, 4.5-6 mm. wide; wings 7-7.9 mm. long, the claws 2.5-3.5 mm., the oblong-obovate or broadly oblanceolate, obtuse, lunately incurved blades 4.8-5.5 mm. long, 1.8-2.2 mm. wide; keel 6.8-7.7 mm. long, the claws 3-3.5 mm., the blades 4-4.7 mm. long, ± 2.2 mm. wide, straight or nearly so in the proximal half and thereafter abruptly incurved through ± 100° to the narrowly triangular, subacute apex; anthers 0.4-0.45 mm. long; pod pendulous, stipitate, the slender stipe 3-4 mm. long, the body narrowly oblong-oblanceolate in profile, gently incurved, 1.8-2.5 cm. long, 3.5-4.5 mm. in diameter, cuneate or tapering at base, abruptly acute and mucronulate at apex, sharply triquetrous, with flat lateral and depressed, openly sulcate dorsal faces, the thin, glabrous, mottled but glaucescent valves becoming papery, stramineous faintly purple-tinged, finely cross-reticulate, the complete septum 1.4-1.9 mm. wide; ovules 11-16; seeds purplish-brown, rugulose, 2.4-2.7 mm. long.

Distribution and Ecology - Gravelly hillsides and benches among piñons and junipers, in stiff calcareous soil, often taking shelter under and entangled with low sagebrush, locally plentiful in the type-locality at about 7000 feet on the east slope of the Toquima Range, Nye County, Nevada.—Map No. 52.—Late April to early July.

Discussion

The Toquima milk-vetch resembles A. Howelli and A. misellus in the form of the pod, but it differs from the first in its fewer leaflets and smaller flowers of a dingy purple hue, from the latter in its more erect habit of growth, and from both in the truly appressed vesture, little- graduated petals, triangular keel-tip, and glabrous, mottled pod. The related species geographically nearest to A. toquimanus, but still some 150 miles distant in a southeasterly direction, is A. straturensis. This, however, is easily distinguished by its bright violet-purple petals with obtusely rounded keel-tip and by the narrower, usually shorter, green but strigulose pod. The glaucescence and mottling of the pod-valves and the relative proportions of the petals are not matched elsewhere among the Miselli and are suggestive of A. bernardinus of sect. Leptocarpi. In this species, however, the pod is held erect and eventually disjoints from a short, stipelike gynophore.

Because of the small size and lurid coloring of the flowers A. toquimanus is one of the least showy of our desert astragali; the delicately shaped and colored fruits are, nevertheless, quietly attractive. The majority of plants observed in the type-locality were growing up through sagebrush (Artemisia arbuscula) or other low shrubs, from which it was difficult to extract an uninjured specimen. The species is to be sought elsewhere on the limestones of central Nevada.

Objects

Specimen - 696107, H. D. D. Ripley 3996, Astragalus toquimanus Barneby, Fabaceae (152.0), Magnoliophyta, paratype; North America, United States of America, Nevada, Nye Co.

Distribution

Nevada United States of America North America|