Utah Cynanchum [Cynanchum utahense (Engelm.) Woods.]

Utah Cynanchum [Cynanchum utahense (Engelm.) Woods.]

Listing CNPS List 4 R-E-D Code 1-1-1

State/Federal. Status -- None ASCLEPIADACEAE Apr.-Jun.

Global Rank G3 State Rank S?

Distribution: San Diego County, Imperial County, Riverside County, and San Bernardino County; Arizona; Nevada; and Utah.

Habitat: Sonoran Desert Scrub and Mojavean Desert Scrub are general habitats utilized by this vine-like shrub. It usually scrambles through shrubs for support. Soils are mapped as Acid Igneous rock land at the Sentenac locale, a locale with arid sandy slopes and relatively low-growing desert shrub cover.

Known Sites: Utah Cynanchum is a very inconspicuous milkweed growing at the western entrance to Sentenac Canyon and winding through shrubbery near the ranger station in Blair Valley. It is difficult to assess the rarity of this species, as it is easy to overlook even when in flower. Herbarium specimens examined are from Sweeny Pass, Dolomite Mine, and Earthquake Valley in San Diego County; as well as at Coyote Wells in Imperial County. Shreve and Wiggins report this vine from southern Nevada, southwestern Utah, and northwestern Arizona. Reported by Thorne at the southeastern bases of the mountain ranges of the eastern Mohave, utilizing dry stony washes.

Status: Utah Cynanchum populations are likely stable on the southern deserts based on limited historical impacts to its habitat. Although apparently more common elsewhere to the east, populations on the western periphery of the Colorado Desert are uncommon and should be protected.

Copyright May 1994 Craig H. Reiser.

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