Dudley Bluffs Bladderpod

views updated

Dudley Bluffs Bladderpod

Lesquerella congesta

ListedFebruary 6, 1990
FamilyCruciferae (Brassicaceae)
DescriptionSmall, cushion-shaped perennial with yellow flowers and silvery leaves.
HabitatOil shale outcrops.


The Lesquerella congesta (Dudley Bluffs bladder-pod), a perennial in the mustard family, is a small plant with a cushion growth form. The fruiting stems are only 0.4-1.2 in (1-3 cm) tall. The small, silvery leaves are less than 0.5 in (12 mm) in length, linear, and untoothed. The species bears bright yellow, four-petaled flowers and small, rounded, downy fruits.


Endemic to barren, white oil shale outcrops in the Piceance Basin of Colorado, Dudley Bluffs bladder-pod grows on flat oil shale ridges and on other level outcrops. It is often found in association with another Threatened mustard, the Dudley Bluffs twin-pod (Physaria obcordata), which grows on the steep oil shale slopes. The species is found at elevations of from 6,140-6,844 ft (1,860-2,010 m). The surrounding hills and mesas support pinyon-juniper woodlands.


Dudley Bluffs bladderpod was discovered in 1982 in Rio Blanco County, northwestern Colorado, during a survey of the plant life of the Piceance Basin conducted by the state Natural Heritage Inventory for the Bureau of Land Management (BLM). The species has not been found outside the Piceance Basin.

This bladderpod is currently found at five sites in Rio Blanco County, mostly on public land administered by BLM. There are five known populations along Piceance and Yellow creeks on approximately 50 acres (20 hectares) over a 10 mi (16 km) range. The largest population, consisting of about 10,000 plants, is located on BLM land at the junction of Piceance Creek and Ryan Gulch. This site also contains an equal number of the Threatened Dudley Bluffs twinpod. Along Yellow Creek the species occurs on BLM land and state land administered by the Colorado Division of Wildlife.


The main threat to the Dudley Bluffs bladderpod is the mining of its habitat for rich deposits of oil shale and sodium minerals such as nahcolite and dawson-ire. While mining is not imminent, long term mineral development plans clearly threaten the species. As the federal government seeks alternative energy sources to imported petroleum, subsidy programs for oil shale development continue to be proposed in the U.S. Congress.

Yellow Creek, Dudley Bluffs, and Ryan Gulch are on oil shale deposits which could be mined by open-pit methods. A pilot project for an underground nahcolite solution mine has been established between Piceance Creek and Yellow Creek, and a commercial mine, which has been proposed for the area would cover 254 acres (103 hectares). These activities could result in the destruction or modification of the entire Dudley Bluffs bladderpod habitat. At this time BLM has decided not to lease the commercial mineral rights to the area until improved mining technology is developed, but is still considering leases for noncommercial research purposes. While BLM has designated a section of Dudley Bluffs as an "Area of Critical Environmental Concern," this gives protection to only about 50 acres (20 hectares).

Although Dudley Bluffs bladderpod is locally abundant in its specialized habitat, its extremely limited range renders it vulnerable to any surface disruptions. The Rio Blanco County government and oil shale and nahcolite companies opposed the listing of Dudley Bluffs bladderpod as a Threatened species.

Conservation and Recovery

The Fish and Wildlife Service published a Recovery Plan for the Dudley Bluffs bladderpod in 1993. Most of its critical habitat is owned by the Bureau of Land Management (BLM), a federal agency. The BLM has designated a section of Dudley Bluffs as an "Area of Critical Environmental Concern," which gives protection to about 50 acres (20 hectares) of critical habitat. Other critical habitat is owned by the Colorado Division of Wildlife. Additional areas of these publicly owned habitats should be protected from threatening activities. Some critical habitat is on private land and should also be protected, either by acquisition and designation as ecological reserves, or by the negotiation of conservation easements with the owner. The populations of the Dudley Bluffs bladderpod should be monitored, and research undertaken into its biology, habitat needs, and beneficial management practices.


U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
P.O. Box 25486
Denver Federal Center
Denver, Colorado 80225


Bureau of Land Management. 1987. "Spiceance Basin Resource Management Plan Record of Decision." U.S. Government Printing Office, Washington, DC.

Colorado Native Plant Society. 1989. Rare Plants of Colorado. Colorado Native Plant Society and the Rocky Mountain Nature Association, Estes Park, Colorado.

Colorado Natural Areas Program. 1987. "Status Report for Physaria obcordata." Denver, Colorado.

U.S. Fish and Wildlife Service. 1993. "Dudley Bluffs Bladderpod and Dudley Bluffs Twinpod Recovery Plan." Denver, Colorado.