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Cuscuta denticulata Engelm.

Desert dodder; Sepal-toothed dodder

Cuscutaceae (Dodder family)

General Description: A rootless, leafless, twining, non-green, parasitic herb with slender, pale yellow stems that grows on various desert shrubs. Flowers are white, sessile or subsessile, single and scattered, or congested into small clusters. The corolla is 5-merous, with lobes about 1.5 mm long, rounded at the apex and irregularly finely toothed. The non-fleshy calyx has deeply divided lobes that are more or less circular in outline. They have irregularly finely-toothed margins, and become shiny-translucent and finely lined when dry. The stamens are shorter than the corolla lobes and have anthers about equaling the filaments. Scales between the stamens are well developed and finely toothed. The styles are capitate. Capsules are narrowly pear-shaped, usually one-seeded, and have a crested thickening around the base of the style.

Photo © Florence Caplow, WANHP CLICK PHOTO FOR A LARGER IMAGE

Illustration.

Field Identification Tips: The genus Cuscuta is readily recognized by its rootless, twining, non-green habit. Field identification to species is difficult due to the small size of the flowers. Features of the stigma, stamens and scales between the stamens are key to identifying species of Cuscuta.

Phenology: Flowers from July through August.

Similar Species: Dodders known to occur in eastern Idaho include Cuscuta indecora (bigseed alfalfa dodder), C. californica (chaparral dodder), C. pentagona (five-angled dodder), C. approximata (alfalfa dodder), and perhaps others. All resemble desert dodder at first glance, and most occur on a wide range of hosts.

Habitat: Occurs on various desert shrubs, especially Artemisia spp. and Chrysothamnus spp.

Global Distribution: California to Nevada, Arizona, and Baja California; with disjunct populations known from Washington and Idaho.

Idaho Distribution: Known from Hells Canyon in Idaho County and the Birch Creek Valley in Clark County.

References:

Cronquist, A., A. H. Holmgren, N. L. Holmgren, J. Reveal, and P. K. Holmgren. 1984. Intermountain Flora. Vascular plants of the Intermountain West, U.S.A. Vol. 4. The New York Botanical Garden, Bronx, NY. 573 pp.

Washington Natural Heritage Program. 2000. Field guide to Washington's rare plants. A cooperative project between Washington Natural Heritage Program and Bureau of Land Management, Spokane District.