Astragalus nutzotinensis J.Rousseau

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 nutzotinensis J.Rousseau

Type

"Type collected between Lake Kluane and Don Jek River, Yukon, August 11-27, 1920, August Muller (type in herb. Acad. Nat. Sci. Phila.)." Holotypus, collected by Adolf Muller, PH!

Synonyms

Gynophoraria falcata Rydb., , Astragalus gynophoraria Tidestr.

Description

Species Description - Low, weak and slender, diffuse or prostrate, with a taproot and loosely, sometimes repeatedly branching, subterranean caudex, thinly and rather loosely strigulose with appressed and narrowly ascending hairs up to 0.3-0.45 mm. long, the herbage green or greenish-cinereous when young, the leaflets glabrous or nearly so above, the inflorescence black-hairy; stems 6-15 cm. long, branched or spurred below the middle, the aerial either shorter or much longer than the buried part; stipules thinly herbaceous becoming papery and brownish, often purplish when young, much broader than the stem, amplexicaul and connate through half to nearly their whole length into a loose, 2-lobed sheath, the lowest ones glabrous, the upper ones strigulose dorsally; leaves 2-6.5 cm. long, with slender petioles and 7-15 (17) broadly oval, oval-ovate or -obovate, more rarely oblong-oblanceolate, obtuse or truncate, sometimes retuse, commonly rather distant leaflets (1) 2-8 mm. long, the ciliate margins elevated or a little inrolled; peduncles ascending, (2.5) 5-8 (10) cm. long, surpassing the leaf, reclinate in fruit; racemes loosely but very shortly (1) 2-4-flowered, the flowers spreading-ascending, the axis scarcely elongating, (0) 2-12 mm. long in fruit, often produced as a subulate appendage beyond the last flower; bracts membranous, purplish, ovate, broadly, lanceolate, or lance-acuminate, 1.5-4.5 mm. long; pedicels ascending or a little arched outward, at anthesis 1.8-3.4 mm., in fruit a little thickened, 2-4 mm. long; bracteoles 0; calyx 6-6.7 mm. long, strigulose with black hairs, the subsymmetric disc 1-1.5 mm. deep, the submembranous, purplish tube 4-4.7 mm. long, 3.7-4.5 mm. in diameter, the subulate teeth 1.9-2.2 mm. long, separated by wide sinuses, the whole becoming papery, marcescent unruptured; petals pink- or reddish- purple; banner gently recurved through ± 30-45°, amply obovate-cuneate, openly notched, 12-17 mm. long, 9-12 mm. wide; wings 11.1-14.6 mm. long, the claws 4.3-6.2 mm., the broadly oblanceolate, obtuse or erose-emarginate, nearly straight blades 7.9-10.3 mm. long, (3) 3.6-5 mm. wide; keel (0.5 mm. longer to 1.6 mm. shorter than the wings) 11.2-13.7 mm. long, the claws 4.5-6.1 mm., the lunately half-elliptic blades 7.4—8.7 mm. long, 3.1—3.5 mm. wide, gently incurved through 50—90° to the obtuse apex; anthers 0.65—0.8 mm. long; pod ascending (humistrate), elevated on a slender, glabrous gynophore 5-10.5 mm. long, the body narrowly oblanceolate or linear-oblong in profile, incurved through one quarter to a whole circle, cuneately or acuminately tapering at base, abruptly deltoid and apiculate at apex, 3—4.5 (5) cm. long, 5-7.5 mm. in diameter, strongly compressed laterally and 2-sided, the faces at first nearly flat, low-convex at maturity, the slender sutures both salient, the thin, pale green, commonly purple-dotted or -suffused valves becoming papery-membranous and subdiaphanous, minutely black- or white-strigulose, not inflexed; seeds olivaceous or pale brown, smooth but dull, 2-2.5 mm. long.

Distribution and Ecology - Silty shores and gravel bars of cold brooks and rivers and stony moraines at the foot of melting ice, about 3000—3200 feet, apparently uncommon, known only from the Alaska Range (McKinley Park) east to the headwaters of the White and Don Jek Rivers in the Nutzotin Mountains, eastcentral Alaska and adjoining Yukon.—Map No. 39.—June to August.

Discussion

The Nutzotin milk-vetch, one of several slender and delicate creeping astragali found in the Alaskan tundra, is similar in general habit of growth to A. alpinus and the Polares. Flowering plants may be distinguished from the former by the mostly few (7-15, not 15 and more) leaflets, and by the fewer, slightly larger flowers; the Polares have flowers substantially smaller if as few and only 2-13 (not 14-25) ovules. The fruit of A. nutzotinensis is unique, being raised out of the calyx on a long stipelike gynophore instead of truly (and more shortly) stipitate as in A. alpinus, or sessile on a scarcely produced receptable as in sect. Polares. Moreover the body of the pod is at once greatly compressed laterally, and either falcately incurved or coiled into a complete ring. Relative to the size of the leaves and leaflets, the flowers of the Nutzotin milk-vetch are notably ample and showy. The species is one of the prettiest found in subarctic regions.

Objects

Specimen - 01267049, J. Wetherell 764, Astragalus nutzotinensis J.Rousseau, Fabaceae (152.0), Magnoliophyta; North America, United States of America, Alaska

Specimen - 01267050, J. Wetherell 766, Astragalus nutzotinensis J.Rousseau, Fabaceae (152.0), Magnoliophyta; North America, United States of America, Alaska

Specimen - 01267055, A. Nelson 3539, Astragalus nutzotinensis J.Rousseau, Fabaceae (152.0), Magnoliophyta; North America, United States of America, Alaska

Distribution

Alaska United States of America North America| Yukon Canada North America|