Psorothamnus thompsonae (Vail) S.L.Welsh & N.D.Atwood var. thompsonae

  • 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

  • Scientific Name

    Psorothamnus thompsonae (Vail) S.L.Welsh & N.D.Atwood var. thompsonae

  • Type

    based on Parosela thompsonae (Ellen Powell Thompson) Vail, Bull. Torrey Club 24: 18. 1897.  "Original locality, Northern Arizona. Type collected by Mrs. Thompson, 1872." Holotypus, collected probably, like some others gathered by Mrs. Thompson and Capt. Bishop on Powell s Grand Canyon Expedition, in southeastern Utah, US! isotypus (fragm), NY!  Dalea thompsonae (Vail) L. O. Wms., Ann. Missouri Bot. Gard. 23: 451. 1936; Tidest. in Tidest. & Kitt., Fl. Ariz. & New Mex. 181. 1941.

  • Synonyms

    Parosela thompsoniae Vail, Dalea thompsoniae (Vail) L.O.Williams

  • Description

    Species Description - Characters as given in key; leaflets never decurrent.— Collections: 13 (iii).

    Distribution and Ecology - Hummocked dunes and dunelike or bouldery talus slopes under cliffs, sometimes colonial along sandy and gravelly washes of the canyon floor, confined to red and white sandstones, 1080-1410 m (3600-4700 ft), locally abundant but of highly restricted range in low valleys and canyons leading to the Colorado River in e.-centr. Wayne, e. Garfield, and lower reaches of White Canyon in adjoining San Juan counties, Utah. — Flowering late May to July.

  • Discussion

    (Plate VII)

    This is one of the most colorful small desert shrubs of its region, the low prickly mounds of twigs and foliage disappearing in May beneath a cloud of vivid pink-purple flowers. The whole plant is strongly scented when crushed, the orange or red glands of the stems yielding an aromatic resinous oil. Until recent years Ps. thompsonae was little known, its range lying in a corner of Utah only lately opened to easy access. Rydberg knew the species only from the type, and failed to notice the insertion of all petals on the hypanthium rim, in consequence accepting it as Parosela, despite its generic characters of Psorothamnus. The known range of var. thompsonae extends from a point about ten miles south of Hanks- ville southeast across the east foothills of the Henry Mountains to Hite, there passing to the east bank of the Colorado River in the lower reaches of White Canyon, a total airline distance of less than 40 miles. It may, of course, recur lower down the Colorado, possibly in Arizona, as suggested in the protologue, but this awaits confirmation in the form of specimens.

  • Distribution

    United States of America North America| Utah United States of America North America|