Monographs Details: Astragalus lentiginosus Douglas ex Hook. var. lentiginosus
Authors:Rupert C. Barneby
Authority: Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(2): 597-1188.
Family:Fabaceae
Synonyms:Tragacantha lentiginosa (Douglas) Kuntze, Phaca lentiginosa (Douglas) Piper, Astragalus lentiginosus var. typicus Barneby, Astragalus lentiginosus var. carinatus M.E.Jones
Description:Variety Description - Perennial, slender, thinly strigulose with subappressed, straight hairs up to 0.35-0.55 mm. long, the herbage green, the leaflets nearly glabrous on both sides and ciliate, sometimes thinly pubescent, especially toward the midrib, beneath; stems decumbent or prostrate, 1-3 (5.5) dm. long, commonly simple and floriferous upward from near the middle, sometimes branched at 1-6 nodes preceding the first peduncle; stipules submembranous, (1.5) 2-6 mm. long, glabrous or nearly so dorsally; leaves 3-10 cm. long, with (5) 9-17 (19) broadly obovate, obovate-cuneate, or oblong-elliptic, sometimes partly suborbicular or oblanceolate, mostly retuse or obtuse, sometimes truncate and apiculate, flat leaflets (3) 5-15 (18) mm. long; peduncles 1-3.5 cm. long, incurved-ascending at anthesis reclinate in fruit; racemes 8-18 (22)-flowered, the axis 0.5-3 (3.5) cm. long in fruit; bracts 1-2.5 mm. long; pedicels at anthesis 1-1.7 mm., in fruit 1.4-2.5 mm. long; calyx 4.1-6.4 mm. long, thinly strigulose with black, white, or mixed hairs, the subsymmetric disc 0.5-0.9 (1) mm. deep, the campanulate tube 2.8-4.2 mm. long, 1.7—2.5 mm. in diameter, the subulate teeth 1—2.2 mm. long; petals whitish or yellowish, the keel-tip and sometimes the base of wings and banner faintly lilac-tinged, banner rhombic-oblanceolate or elliptic, 7.4—11 mm. long, 4.5—6.2 mm. wide; wings 7.1-9.4 mm. long, the claws 2.5-3.9 mm., the blades 4.7-6.5 mm. long, 1.1—2 mm. wide; keel (mostly 0.6—1.9 mm. shorter, rarely up to 0.6 mm. longer than the wings) 6.3-8.4 mm. long, the claws 2.7-4 mm., the blades 3.4-5.6 mm. long, 1.7—2.4 mm. wide; anthers 0.35—0.55 mm. long; pod humistrate, variable in size, outline, and curvature, obliquely ovate- to lance-acuminate in profile, strongly to scarcely inflated, 1—2.3 cm. long, (3) 4.5—10 mm. in diameter, lunately to hamately incurved, rounded (rarely broadly cuneate) at base, tapering or abruptly contracted distally into an unilocular beak 4—9 mm. long, the body a little obcompressed, when inflated sulcate along both sutures, when tumescent sulcate only ventrally or only dorsally, the stiffly papery or subcoriaceous, pale green but often purple-speckled or -mottled, thinly strigulose (exceptionally glabrous) valves becoming stramineous or brownish, cross-reticulate, not diaphanous, the septum complete or nearly so, (1.8) 2—5 (6.5) mm. wide, the funicular flange 0.4—1 mm. wide; ovules (15) 16—21.

Distribution and Ecology - Dry plains and hillsides, in volcanic soils, commonly on basalt, among sagebrush or sometimes in open yellow pine forest, 750—4750 feet, widespread and locally plentiful in the Columbia Basin from Fort Okanogan south through transmontane Washington and Oregon to the Klamath Basin and Lassen County in northeastern California and to extreme northwestern Nevada; southeast in scattered stations up the Snake River to Pocatello, Idaho; apparently somewhat isolated on the Fraser River (Kamloops and vicinity) in southern British Columbia.—Map No. 127.—May to early July.

Discussion:

The typical variety of the freckled milk-vetch is the prototype of a series of forms which have in common prostrate or diffuse stems and compact, shortly pedunculate racemes of small, whitish flowers. It is the only astragalus of its sort in Washington and British Columbia, but southward it is sympatric with var. salinus and var. platyphyllidius, both of which are or may be at times closely similar in habit and vesture. The former is distinguished ideally by its thinly papery, translucent pod, but south of the Blue Mountains ambiguous populations are quite frequent. The flower of var. platyphyllidius, which has normally a larger pod of stiffer texture than that of var. lentiginosus, is commonly much larger, the banner nearly always over 14 mm., not 7.5-11 mm. long.

The pod of var. lentiginosus varies considerably in the degree of inflation; forms with strongly incurved and little-swollen pods are rather common toward the southeast and south limits of the variety’s range in Idaho and California. An extreme example from Idaho (Mrs. Soth 399) has been illustrated (Barneby, 1945, Pl. 1, fig. 3). I no longer feel justified in maintaining Jones’s var. carinatus (= var. cuspidocarpus sensu Jeps., 1936, p. 356) which I formerly (l.c.) distinguished by its "regularly falcate legume devoid of ventral sulcus." The degree to which the pod is grooved, whether dorsally or ventrally, is a function of the inflation modified by the curvature, and is too variable to serve as a differential character. The plants of northeastern California and the lake country of nearby Oregon have a certain individual facies but apparently no unique attribute. The typus of var. carinatus was a peculiar plant from the Blue Mountains with petals irregularly graduated, the keel being enlarged and shortly exserted from between the wings. A similar form has been collected in Modoc County, California, and represents no more than a rare and casual aberration, known to occur also in var. platyphyllidius.

Distribution:Washington United States of America North America| Oregon United States of America North America| California United States of America North America| Nevada United States of America North America| Idaho United States of America North America| British Columbia Canada North America|