Fish and Wildlife Service seal
Endangered Species Program
bladderpod with quartertwinpod small

Photos by Steve O'Kane

Species Description: Both the Dudley Bluffs bladderpod (Physaria congesta or Lesquerella congesta) and the Dudley Bluffs twinpod (Physaria obcordata) are rare members of the Brassicaceae (mustard) family. Dudley Bluffs bladderpod is an extremely small cushion plant only 0.4 to 1.2 inches in diameter with a congested mass of bright yellow flowers and narrow silvery leaves rising from a long, thin taproot. The cushion growth habit is an adapatation to erosive badland soils, which has evolved independently in several unrelated taxa in this area. Flowering is typically during April and May, and fruit set from late May into June.

Dudley Bluffs twinpod is 4.8 to 7.2 inches tall with oblanceolate, entire leaves 0.4 to 0.6 inches wide and 1.6 to 3.8 inches long, with a silvery sheen due to a dense covering of overlapping, dish-shaped trichomes. The species' scientific name refers to the hear-shaped silique or fruit. Flowers are yellow, and typically present in May and June.

Location: These two rare mustards grow on barren white outcrops exposed along drainages by erosion from downcutting of streams in the Picaence Basin in Rio Blanco County, Colorado. The bladderpod is the rarer of the two species; its entire range is limited to within 10 miles of the original type locality. The range of Dudley Bluffs twinpod is slightly broader, with some occurances separated by as much as 23 miles. While the twinpod grows on steep sideslopes, the bladderpod grows on the top and sides of level outcrops where the white shale is exposed.

Recent Actions: On February 6, 1990, the U.S. Fish and Wildlife Service (Service) determined Dudley Bluffs bladderpod and Dudley Bluffs twinpod from Rio Blanco County, Colorado, to be threatened species under the authority of the Endangered Species Act of 1973, as amended. A recent taxonomic revision for Dudley Bluffs bladderpod inited the genus Lesquerella with Physaria. Thus, the scientific name has changed from Lesquerellq congesta to Physaria congesta. This revision has not yet been incorporated into the official listing of the species.

In June 2008, the Service completed a 5-year review of the status of the Dudley Bluffs twinpod and bladderpd. This status review conclued non change in its listed status under the Endangered Species Act was necessary.

More information can be found on the Service's ECOS webpages:
Dudley Bluffs bladderpod Dudley Bluffs twinpod

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