Photo © Douglass Henderson
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Ipomopsis polycladon (Torr.) V. Grant

Spreading ipomopsis; Manybranched ipomopsis

Polemoniaceae (Phlox family)

Synonym: Gilia polycladon Torr. (Spreading gilia)

General Description: A taprooted annual up to about 15 cm tall with several slender, rigid, ascending-spreading (not prostrate) branches from the base. The herbage is glandular and hairy, with the stems more glandular, the leaves more hairy. Leaves are clustered at the base and again just below the flower heads, otherwise the stems are leafless or nearly so. Basal leaves are 1-3 cm long and have a few lobes or teeth. Those subtending the flower heads are similar or smaller and less cleft. The inflorescence is a dense cluster of small, white flowers terminating the branches. Corollas are 3-6 mm long and have small spreading lobes, while the calyx is 2-6 mm long and pointy-tipped.

Illustration.

Field Identification Tips: Spreading ipomopsis is recognized by its slender, stiff, divaricate, subnaked, ascending-spreading stems branching from the base, and terminal, leafy-bracted flower heads. Additional characteristics include the lobed or toothed basal cluster of leaves, the glandular and hairy herbage, and dense head of small white flowers.

Photo © Duane Atwood
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Phenology: Flowers April through June.

Similar Species: A few other desert annuals such as Gilia leptomeria, Phacelia glandulifera, or Navarretia spp. can look superficially similar.

Habitat: Dry, open areas in desert shrub communities. In southwestern Idaho, spreading ipomopsis occurs in Artemisia tridentata ssp. wyomingensis and desert shrub communities. It occurs on silt, sand, and clay soils, or on cindery or gravelly exposures that tend to be flat to gently sloping. Associated species include A. tridentata ssp. wyomingensis, Atriplex confertifolia, Chrysothamnus spp., Tetradymia glabrata, Grayia spinosa, Achnatherum hymenoides, Bromus tectorum, Stanleya pinnata, Mentzelia albicaulis, and Phlox spp. In eastern Idaho, spreading ipomopsis is usually associated with rocky Artemisia nova slopes on volcanic substrates. Associated species at eastern Idaho sites include A. nova, Leymus salinus, and Pseudoroegneria spicata.

Global Distribution: Mexico, northward to California, west Texas, New Mexico, Arizona, western Colorado and Wyoming, most of Utah and Nevada, southern Idaho and adjacent Oregon.

Idaho Distribution: Populations are known from Ada, Elmore, and Owyhee counties in southwestern Idaho, and Butte and Power counties in the eastern part of the state.

References:

Atwood, D., A. DeBolt, and B. Cheney. 2000. Field guide to the special status plants of the Bureau of Land Management Lower Snake River District. Bureau of Land Management, Lower Snake River District, Boise, ID.

Cholewa, A. F., and D. M. Henderson. 1984. A survey and assessment of the rare vascular plants of the Idaho National Engineering Laboratory. DOE/ID-12100. U.S. Department of Energy, Idaho Operations Office, Radiological and Environmental Sciences Laboratory, Idaho Falls, ID. 45 pp.