Malheur Wire-lettuce

Stephanomeria malheurensis

Description

Malheur wire-lettuce, Stephanomeria malheurensis, is an herbaceous annual that forms a heavy rosette of scalelike leaves at the base and puts up many branched stems to a height of 20 in (50 cm). Numerous pink to white (rarely yellow-orange) flower heads appear in July and August. The number of individual plants varies significantly from year to year depending on the amount of rainfall received during the spring growing season.

Habitat

The site of the only known population of Malheur wire-lettuce is within the high desert environment typical of the northern portion of the Great Basin. The plant grows on a broad hill overlooking a sagebrush-rabbitbrush desert. The immediate site itself is dominated by big sagebrush, common or gray rabbitbrush, green rabbitbrush, and cheat-grass. The wire-lettuce seems to be one of the few species able to survive on or around the otherwise barren harvester ant hills at the site. The azonal soil is derived from volcanic tuff, often overlain with thin crusts of limestone.

Distribution

Malheur wire-lettuce is found at a 70-acre (32-hectare) site near Malheur National Wildlife Refuge in Harney County, Oregon. The population occurs on lands managed by the U.S. Bureau of Land Management (BLM). Early population estimates set the number of plants at 12,000 in 1974 and 35,000 in 1975. In 1980, however, a diligent search turned up only a few dozen plants. This drastic decline in numbers was attributed to the encroachment of the non-native cheatgrass. The 1991 Recovery Plan for the species, from the U.S. Fish and Wildlife Service (FWS) described population levels as ranging from one to 1,050.

Threats

Competition from cheatgrass (Bromus tectorum ) poses an immediate threat to the survival of the wire-lettuce. Cheatgrass gained a foothold in the habitat in 1972 when a controlled burn disrupted the natural balance of vegetation. Cheatgrass, with its habit of growing in tight clumps, forces out other plants.

Black-tailed jackrabbits, feeding on seedlings, have also taken a toll on plants and have contributed to a decline in reproductive success. The extremely restricted range and low numbers of this plant make it vulnerable to any disturbance of the habitat.

Conservation and Recovery

One hundred sixty acres (65 hectares) have been set aside as a scientific study area and designated as critical habitat for the species. In managing this area, botanists have removed cheatgrass and have implemented a program to control the jackrabbit population. The Anaconda Minerals Company, which leases mining claims in the area, is cooperating with FWS and BLM to conserve the species and has fenced the study area to prevent disturbance by off-road vehicles.

The 1991 Recovery Plan anticipated the event of downlisting of Malheur. The downlisting is deemed subject to the establishment of a secure environment in the 160-acre (65-hectare) critical habitat, to protect from the threats of fire, mining, grazing, and introduced exotic species for five years. Downlisting is further dependent upon production of seeds by flowering plants in at least four separate locations within the habitat. With recovery goals satisfied, and with effective implementation of a plan calling for the securing and management of the critical habitat, research on the biology of the species, and the establishment of additional plants and/or populations, downlisting may proceed in 2003.

Although numbers remained critically low in the late 1990s, wire-lettuce was responding favorably to these efforts, and the population was slowly expanding.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

References

Gottlieb, L. D. 1973. "Genetic Differentiation, Sympatric Speciation, and the Origin of a Diploid Species of Stephanomeria. " American Journal of Botany 6 (60): 545-553.

Gottlieb, L. D. 1977. "Phenotypic Variation in Stephanomeria exigua ssp. coronaria (Compositae) and Its Recent Derivative Species malheurensis. " American Journal of Botany 7 (64): 874-880.

Gottlieb, L. D. 1978. " Stephanomeria malheurensis (Compositae): A New Species from Oregon." Madroño 1 (25): 44-46.

U.S. Fish and Wildlife Service. 1991. " Stephanomeria malheurensis Recovery Plan." U.S. Fish and Wild-life Service, Portland.