Monographs Details: Psorothamnus polydenius (Torr. ex S.Watson) Rydb. var. polydenius
Authors:Rupert C. Barneby
Authority: Barneby, Rupert C. 1977. Daleae Imagines, an illustrated revision of Errazurizia Philippi, Psorothamnus Rydberg, Marine Liebmann, and Dalea Lucanus emen. Barneby, including all species of Leguminosae tribe Amorpheae Borissova ever referred to Dalea. Mem. New York Bot. Gard. 27: 1-892.
Family:Fabaceae
Synonyms:Dalea polydenia var. subnuda S.Watson, Parosela polydenia var. subnuda (S.Watson) Parish, Psorothamnus subnudus (S.Watson) Rydb., Parosela polydenia (Torr. ex S.Watson) A.Heller
Description:Species Description - Leaves small, distant, the leaflets 3-6 pairs, obovate to suborbicular, 1-3 mm long; calyx either pilosulous equably from base upward (the hairs up to 0.3-0.6, rarely 0.7 mm long), or the tube externally glabrous and lustrous, only the teeth pilosulous; otherwise as in key; 2n = 10 II (Raven, Kyhos & Hill, 1965); 2n = 10 (Spellenberg, 1970). — Collections: 54 (o, sed pluries sterilem vidi).

Distribution - Sandy and gravelly, often alkaline flats and low hills, commonly associated with chenopods, sometimes on dunes, 880-2250 m (2930-7500 ft), forming colonies but seldom crowded into thickets, widespread through the basins of w. Nevada and along e. foothills of Sierra Nevada in adjoining California from Smoke Creek Desert and the Humboldt and Carson sinks s. to Owens Valley, and somewhat disjunctly to central Mohave Desert in San Bernardino County, in Nevada s. to s. Nye County and thence e., rarely, to the Beaver Dam Mountains in s.-w. Washington County, Utah. - Flowering mid-May to September, the fruits ripe from July onward.

Discussion:

(Plate VI)

Typical Ps. polydenius varies in stature, the adult plant taking the form of a depressed dome of stiffly enlaced branchlets or, in favorable conditions, that of a definite bush or shrub with one or more softly woody trunks. The only notable variation in detail is that, often noticed, in vesture of the calyx, which may be either pubescent from base upward or externally glabrous below the pilosulous teeth. The form with glabrate, vernicose calyx- tube has been collected repeatedly in Owen’s Valley, California, near Independence, Laws, and Bishop in Inyo County, and near Benton in southern Mono County, and seems where present to exclude the pubescent form. This, however, occurs in the same region, near Deep Springs and Eureka Valley, as well as in immediately adjoining Esmeralda County, Nevada and on the central Mohave Desert. Exactly parallel variants are known in Ps. schottii and the quite local Ps. thompsonae, in both cases geographically localized but not displacing the commoner, more pubescent type. All are interpreted here as minor variants of no taxonomic consequence.

Distribution:United States of America North America| Utah United States of America North America| Nevada United States of America North America| California United States of America North America| Washington United States of America North America|

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