Endangered Species Recovery Program

5. Temblor Buckwheat (Eriogonum temblorense)

• Taxonomy
• Description
• Historical Distribution
• Current Distribution
• Life History and Habitat
• Reasons for Decline and Threats to Survival
• Conservation Efforts
• Conservation Strategy

Taxonomy.-- Temblor buckwheat was named Eriogonum temblorense by Howell and Twisselmann (1963) and is a member of the buckwheat family (Polygonaceae). The type specimen was collected by Twisselmann in Chico Martinez Canyon, in Kern County. The scientific name has remained unchanged since it was published, but various authors (Hoover 1970, Reveal 1989, Hickman 1993, Skinner and Pavlik 1994, Skinner et al. 1995) have speculated that Temblor buckwheat should be combined with Eastwoods buckwheat (E. eastwoodianum).

Description.-- The height of Temblor buckwheat ranges from 10 to 80 centimeters (4 to 30 inches) and varies with precipitation. The leaves occur primarily at the base of the plant and are densely covered with matted hairs on both surfaces. The appearance of individual plants of Temblor buckwheat may vary from spring to fall, with the blades rounded early in the year and more elliptical later (Hoover 1970). The branches, which are elongated and spreading, bear flowers only at their tips, where several 2-millimeter (0.08-inch) long, white flowers are clustered inside a cup-like structure. Temblor buckwheat is differentiated from Eastwoods buckwheat and another closely related species, Idria buckwheat (E. vestitum), by the placement of the leaves and the size and surface texture of certain flower parts (Reveal 1989, Hickman 1993). However, the spring form of Temblor buckwheat closely resembles Eastwoods buckwheat (Hoover 1970).

Historical Distribution.-- The range of Temblor buckwheat apparently always has been restricted. The historical distribution is based on 19 collections, which are lustered in eight areas of the inner Coast Ranges: Chico Martinez Canyon and the Shale Hills in Kern County; Indian Valley, Parkfield Grade, and Stone Canyon in Monterey County; and Polonio Pass, Cottonwood Pass, and the Shandon area in San Luis Obispo County (Twisselmann 1967, Hoover 1970, CDFG 1995).

Current Distribution.-- The historical occurrences have not been revisited in recent years but are believed to be extant (Skinner and Pavlik 1994). Another center of occurrence was discovered on the Elkhorn Plain in 1995 (Figure 22).

Figure 22. Distribution of Temblor buckwheat (Eriogonum temblorense).

Life History and Habitat.-- Temblor buckwheat is an annual, but it differs from most annuals of the San Joaquin Valley in that it flowers during the hottest part of the year, from May through September (Twisselmann 1967, Reveal 1989, Skinner and Pavlik 1994). Other aspects of its life history have not been investigated. Temblor buckwheat typically occurs on white, shattered shale (Twisselmann 1967, R. Lewis pers. comm.) and occasionally on sandstone (Hickman 1993). The shale areas are dry and nearly barren of other vegetation, but California buckwheat (Eriogonum fasciculatum), sun cups (Camissonia californica), and Booths evening- primrose (C. boothii) may be present (Lewis in litt. 1995, D. Taylor pers. comm.). The type locality was characterized by saltbush scrub (CDFG unprocessed data). All reported sites for Temblor buckwheat are below 1,000 meters (3,300 feet) in elevation (Hickman 1993). The Elkhorn Plain metapopulation occurs on slopes of 0 to 25 percent (Lewis in litt. 1995).

Reasons for Decline and Threats to Survival.-- The current status of Temblor buckwheat is unknown because threats have not been evaluated at the historical locations. The Elkhorn Plain metapopulation occurs on USBLM land that is protected as an Area of Critical Environmental Concern (USBLM 1996a,b). Only one minor threat was noted by Lewis on the Elkhorn Plain (in litt. 1995): some plants were trampled by cattle in the vicinity of a water trough. The other historical localities are on private property in areas that currently are not desirable for development.

Conservation Efforts.-- Russ Lewis (pers. comm.) of USBLM conducted surveys for Temblor buckwheat in potential habitats of the southern Caliente Range, southern Temblor Range (south of Crocker Grade), and the Maricopa area in 1995. He found the species only on the Elkhorn Plain. Temblor buckwheat possibly could occur on USBLMs proposed Chico Martinez Area of Critical Environmental Concern (USBLM 1996a,b), but surveys would be necessary to verify the presence of the species there.

Conservation Strategy.-- To ensure the long-term conservation of Temblor buckwheat, the strategy is to protect at least five populations representing the full geographic range of the species. Protected areas should be natural land in blocks of at least 65 hectares (160 acres) and should contain a minimum of 1,000 individuals to reduce the likelihood of extinction from intrinsic or random processes. Historical locations of Temblor buckwheat should be surveyed to verify whether the species still persists, to evaluate threats, and to obtain population estimates. Periodic monitoring of the populations is recommended, particularly on the Elkhorn Plain due to the potential impacts of cattle trampling. Current management should be continued in all areas where the species is found; if the populations decrease in favorable years, changes in management may be necessary. Biosystematic studies would be valuable to establish the relationship of plants in this complex (Skinner et al. 1995), but this task is of low priority. When surveys have been completed, or at a maximum within 10 years of recovery plan approval, the status of Temblor buckwheat should be reevaluated.