Malheur wirelettuce was federally listed as endangered with critical habitat in 1982 (U.S. Fish and Wildlife Service 1982). A recovery plan was published in 1991 (U.S. Fish and Wildlife Service 1991).

Historical Status and Current Trends

The first discovery of Malheur wirelettuce was in 1966 when seeds of this species were collected with those from a population of its ancestral plant, small wirelettuce.

This species is an annual and its numbers vary greatly from year to year, depending largely on the amount of precipitation prior to and during the spring growing season. In 1974, the population was estimated at 228 plants and in 1975 the numbers grew to 1,050. During the 1980's, very low numbers of plants were found, and in 1985, 1986 and 1999, no plants were observed. During this time when the species numbers dwindled to zero, cheatgrass (Bromus tectorum) an extremely aggressive non-native grass species dramatically increased at the site. A reintroduction program was begun in April 1987 and 1000 seedlings obtained from the Berry Botanic Garden were transplanted into study plots at the site. Of these plants, 412 survived and one wild plant was found. During subsequent years, efforts have been undertaken to remove cheatgrass from around existing plants and study plots; however, numbers of Malheur wirelettuce remain low.

Description and Life History

Malheur wirelettuce is an annual plant in the composite family (Asteraceae). It can reach 5 dm (20 inches) in height. This species forms a rosette of hairless leaves that arise from its base. The single stems are many-branched with scale-like leaves. Flower heads are either numerous and clustered, or solitary on short stems. The strap-shaped petals are pink, white, or rarely orange-yellow. Flowering typically occurs in July and August.

The Malheur wirelettuce is co-located with an ancestral relative, small wirelettuce (Stephanomeria. exiqua ssp. coronaria); however, the two species do not interbreed. While the Malheur wirelettuce is self-pollinating, its ancestral relative is not.

Habitat

Malheur wirelettuce occurs in the high desert of the northern portion of the Great Basin and is located in an area south of Burns, Oregon. It occurs on top of a dry, broad hill on volcanic soil intermixed with layers of limestone. Dominant plants at the site are big sagebrush (Artemisia tridentata), gray rabbitbrush (Chrysothamnus nauseosus), green rabbitbrush (Chrysothamnus viscidiflorus), and, more recently, cheatgrass. Malheur wirelettuce may be one of the few species able to survive on and around the otherwise barren harvester ant hills at the site.

Reasons for Decline

Malheur wirelettuce is in great danger of extinction due to its small population size. Natural fluctuations in population numbers that occur in response to variations in annual rainfall and spring frosts are particularly problematic for small populations. The species is also vulnerable to habitat alteration; surface mining for zeolite was a potential threat at the time of listing. Other immediate threats include competition from cheatgrass and predation by native herbivores such as black-tailed jackrabbits.

Conservation Measures

Critical habitat for Malheur wirelettuce was designated at the time of listing in 1982. This designation identifies the specific area containing the necessary physical and biological requirements for the conservation of the species. The designation of critical habitat provides additional protection for the species. The area within the designated critical habitat was set aside to allow for natural expansion of the population and to provide a buffer against potential adverse impacts from activities on adjacent lands. In 1984, the Bureau of Land Management (BLM) designated the known location of Malheur wirelettuce as the South Narrows Area of Critical Environmental Concern. The 160-acre area has been fenced since 1974 to prevent grazing by livestock. Monitoring of Malheur wirelettuce population is regularly conducted by BLM botanists.

In 1986 the Service completed the Malheur Wirelettuce Recovery Plan which identified various tasks that are necessary to recover the species. The primary tasks are to maintain and enhance existing populations and habitat, conduct systematic searches for new populations, secure any newly found populations, and develop management and monitoring programs for the species. The U.S. Fish and Wildlife Service, in cooperation with the BLM, developed the "Study Plan for Stephanomeria malheurensis" to identify research needs and management options for the maintenance of a viable self-perpetuating population of Malheur wirelettuce. Range Malheur wirelettuce occurs at only one location on approximately 70 acres of public lands managed by the BLM.

References and Links

U.S. Fish and Wildlife Service. 1982. Determination of Stephanomeria malheurensis (Malheur wirelettuce) to be an Endangered Species, With Determination of Critical Habitat. Federal Register 47:50881-50886. https://ecos.fws.gov/docs/frdocs/1982/82-30881.pdf

U.S. Fish and Wildlife Service. 1991. Stephanomeria malheurensis (Malheur Wirelettuce) Recovery Plan. Portland, Oregon. 34pp. http://ecos.fws.gov/docs/recovery_plans/1991/910321.pdf