Frisco Buckwheat (Eriogonum soredium)
Eriogonum soredium (Frisco buckwheat) is a low mound-forming perennial plant in the buckwheat family (Polygonaceae). For the purposes of this document, we will refer to Eriogonum soredium as “Frisco buckwheat.” The plant is 0.8 to 1.6 inches (in.) (2 to 4 centimeters (cm)) tall and 3.9 to 19.7 in. (10 to 50 cm) across (Welsh et al. 2008). The leaves are 0.08 to 0.2 in. (2 to 5 millimeters (mm)) long, 0.03 to 0.08 in. (0.7 to 2 mm) wide, round to oval, and covered on both surfaces by short, white, wooly hairs (Welsh et al. 2008). The numerous flowers are arranged in tight clusters resembling drumsticks. Individual flowers are white or partially pink and 0.08 to 0.12 in. (2 to 3 mm) long (Welsh et al. 2008).
- States/US Territories in which the Frisco Buckwheat is known to or is believed to occur: Utah
- US Counties in which the Frisco Buckwheat is known to or is believed to occur: View All
- Countries in which the the Frisco Buckwheat is known to occur: United States
|Status||Date Listed||Lead Region||Where Listed|
|Mountain-Prairie Region (Region 6)|
» Candidate Information
» Federal Register Documents
» Conservation Plans
No conservation plans have been created for Frisco Buckwheat.
» Life History
Frisco buckwheat is a narrow endemic restricted to soils derived from Ordovician limestone outcrops (Evenden 1998). There are approximately 845 acres (ac) (342 hectares (ha)) of Ordovician limestone outcrops in the San Francisco Mountains (Miller 2010g). In addition, there are 719 ac (291 ha) of Cambrian dolomite substrates in the San Francisco Mountains; there is the potential for small “islands” of Ordovician limestone outcrops to occur within these substrates (Miller 2010g). We do not know if there are other limiting factors associated with the limestone formations that restrict the habitat use and distribution of Frisco buckwheat within this suitable habitat substrate, but E. soredium occupies only a fraction of the available habitat. Ordovician limestone is rare within a 50-mile (mi) (80-kilometer (km)) radius of the San Francisco Mountains (Miller 2010g). Cambrian dolomite substrates are present in the Wah Wah Mountains to the west of the San Francisco Mountains (Miller 2010g). However, there is no indication that additional populations of the species occur in these areas. Frisco buckwheat is associated with pinion-juniper and sagebrush communities between 6,200 and 7,228 ft (1,890 and 2,203 m) in elevation. Plants are typically found on sparsely vegetated exposed slopes with Ephedra spp. (Mormon tea), Gutierrezia sarothrae (snakeweed), Cercocarpus intricatus (dwarf mountain-mahogany), and Petradoria pumila (rock goldenrod). Associated rare species include Lepidium ostleri (Ostler’s peppergrass) and Trifolium friscanum (Frisco clover).
Movement / Home Range
The total range of this species is less than 5 square miles (sq mi) (13 square kilometers (sq km)) and each of the four populations occupy relatively small areas ranging between 5 ac (2 ha) to 29 ac (12 ha), with localized high densities of plants (Evenden 1989; Miller 2010g). The total area occupied by Frisco buckwheat is only 52 ac (21 ha), or just 6 percent, of the available Ordovician limestone outcrops. All four populations are on private lands in the southern San Francisco Mountains in Beaver County, Utah (Miller 2010g; Roth 2010). We are not aware of any additional populations. Surveys were conducted on Bureau of Land Management (BLM) lands adjacent to the known populations in 2010, and no plants or habitat were found (Miller 2010g, Appendix B and p. 6; Roth 2010, pp. 1–3); however, these adjacent areas do not contain Ordovician Limestone, the substrate that supports E. soredium (Miller 2010g). Similarly, no additional populations of this species was found during surveys of the San Francisco Mountains and surrounding ranges (including the Wah Wah Mountains, Crystal Peak, the Confusion Range, and the Mountain Home Range) (Kass 1992; Evenden 1998; Robinson 2004; Miller 2010c; Roth 2010).
Flowering generally occurs from June to August. The seeds, which are 0.08 to 0.10 in. (2 to 2.5 mm) long, mature from July through September (Welsh et al. 2008). We do not have a clear understanding of the reproductive biology or life history of Frisco buckwheat, but recruitment appears to be low or perhaps episodic (Kass 1992; Roth 2010). Juvenile plants and seedlings have been observed in only two of the four populations (Miller 2010g). In 2010, dead or partially dead plants were found throughout all populations, but we have no information on the cause of death or the approximate number of dead plants (Miller 2010g).
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