Coachella Valley Milk-vetch

Astragalus lentiginosus var. coachellae

Description

Coachella Valley milk-vetch, Astragalus lentiginosus var. coachellae is an erect winter annual or short-lived perennial, 8-12 in (20.3-30.5 cm) tall and covered with white silky hairs. The flowers are deep pink-purple, in a loose or dense 13-25-flowered raceme (an inflorescence in which stalked flowers are arranged singly along a central stem). The two-chambered fruits are strongly inflated.

Habitat

Coachella Valley milk-vetch is found on loose wind-blown or alluvial sands on dunes or flats in the Coachella Valley, Riverside County, California.

Distribution

The historical abundance of Coachella Valley milk-vetch in the Coachella Valley is unknown. Twenty to 25 occurrences of Coachella Valley milk-vetch have been recorded as extant in the 1990s, and 90% of these were located within 3 mi (5 km) of Interstate 10 from north of Indio to Cabazon. About 20-25% of the occurrence of Coachella Valley milk-vetch is protected in the three preserves of the Coachella Valley Preserve System. The largest preserve protects populations of Coachella Valley milk-vetch in the southeastern part of its range, and two other preserves in the central range of this taxon also support populations. The Coachella Valley Preserve System, jointly owned and managed by the U.S. Bureau of Land Management, The Nature Conservancy (TNC), California Department of Fish and Game (CDFG), California Department of Parks and Recreation, and the U.S. Fish and Wildlife Service (FWS), was established in 1986. The mission of the reserve is to conserve habitat for the federally threatened Coachella Valley fringe-toed lizard (Uma inornata ) and other taxa endemic to the habitats of the Coachella Valley. None of the plants in the northwestern part of the range of Coachella Valley milk-vetch are currently protected, although the Coachella Valley Mountains Conservancy may acquire habitat in this region. About 75-80% of the occurrence of Coachella Valley milk-vetch is located on unprotected lands. Of those, about 7% are on lands owned by Southern California Edison, about 7% are on lands owned by the Agua Caliente Indian Reservation, and the remainder is privately owned.

Population sizes vary widely from year to year, depending on environmental conditions, making assessment of total numbers of individual plants difficult. At sites where Coachella Valley milk-vetch was monitored in 1995, densities varied from 0.67 plants per acre (1.25 plants per hectare) to 24 plants per acre (60 plants per hectare) according to Sanders and Thomas Olsen Associates in 1995. One of the largest known remainig sites for this taxon occurs in the north, near Snow Creek Road. In 1995, this area supported about 24 plants per acre (60 plants per hectare), the greatest density of Coachella Valley milk-vetch found during 1995 surveys.

Threats

The primary threat to Coachella Valley milk-vetch is habitat destruction due to the extensive urban development occurring in the Coachella Valley. Urbanization destroys populations by direct conversion of the land on which they occur and by altering or reducing the source and transport of blow sands that maintain the sand habitat of the Coachella Valley. Populations of Coachella Valley milk-vetch have been altered by development of wind energy parks and degraded by off-highway vehicle use. Initially, Coachella Valley milk-vetch may respond favorably to low levels of artificial disturbance, but its long-term response in these situations is unknown.

Conservation and Recovery

Coachella Valley milk-vetch occurs within the bounds of the Coachella Valley multispecies habitat conservation planning area. This planning process, coordinated by the Coachella Valley Association of Governments and the Coachella Valley Mountains Conservancy, addresses a 1,850-sq mi (4,763.6-sq km) area that includes the Coachella Valley and surrounding region in Riverside County. The plan is expected to address conservation needs for 12 species that are listed or proposed for listing as endangered or threatened species, 21 candidate species, and 17 additional species of concern to FWS. However, the planning process is in its initial stages and its funding is not secured, nor is a product yet available that can be implemented.

The range of Coachella Valley milk-vetch overlaps with that of the Coachella Valley fringe-toed lizard. The three preserves set aside for the lizard support populations of Coachella Valley milk-vetch, but this represents only 20-25% of the occurrences of this taxon. More than 75% of the occurrences of this plant are located on unprotected sites on private or tribal lands.

Contact

Regional Office of Endangered Species
U. S. Fish and Wildlife Service
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232
http://pacific.fws.gov/

Reference

U. S. Fish and Wildlife Service. 6 October 1998. "Determination of Endangered or Threatened Status for Five Desert Milk-vetch Taxa from California." Federal Register 63 (193): 53596-53615.