Frisco clover (Trifolium friscanum)
Trifolium friscanum (Frisco clover) is a dwarf mat-forming or tufted perennial herb in the legume family (Fabaceae). For the purposes of this document, we will refer to Trifolium friscanum as “Frisco clover.” Plants have a taproot and thick woody stem. Frisco clover is up to 1.2 inches (3 centimeter) tall and has silver hairy leaves composed of three leaflets (Welsh et al. 2008). Its flowers resemble those of other clover species and are arranged in heads of four to nine reddish-purple flowers with pale wings (Welsh et al. 2008).
- States/US Territories in which the Frisco clover is known to or is believed to occur: Utah
- US Counties in which the Frisco clover is known to or is believed to occur: View All
- Countries in which the the Frisco clover 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 clover.
» Life History
Frisco clover is a narrow endemic restricted to soils derived from volcanic gravels, Ordovician limestone, and dolomite outcrops. Soils are shallow, with gravels, rocks, and boulders on the surface (Kass 1992; Miller 2010d). In the southern San Francisco Mountains, where the majority of plants are located, there are 845 acres (ac) (342 hectares (ha)) of Ordovician limestone and 719 ac (291 ha) of dolomite outcrops (Darnall et al. 2010, entire). Ordovician limestone is rare within a 50-mile (mi) (80-kilometer (km)) radius of the San Francisco Mountains, but dolomite outcrops are common in the Wah Wah Mountain Range to the west (Miller 2010g). We have no information on the extent of volcanic gravels in the area. We do not know if there are other limiting factors associated with the limestone and dolomite formations that restrict the habitat use and distribution of the species; the species occupies only a fraction of the available habitat. The two largest populations— Grampian Hill and San Francisco—occupy an estimated 35 ac (14 ha) (2.3 percent) of the available limestone and dolomite outcrops (Darnall et al. 2010, entire). We do not have occupied habitat area totals for the remaining three populations, but we believe they are smaller, based on field evaluations and the lower number of individuals in these populations (Kass 1992; Miller 2010d; Roth 2010). Frisco clover is typically found within sparsely vegetated pinion-juniper-sagebrush communities between 5,640 and 8,440 feet (1,720–2,573 meters) in elevation. Associated species include Ephedra spp. (Mormon tea), Gutierrezia sarothrae (snakeweed), Cercocarpus intricatus (dwarf mountain-mahogany), and Petradoria pumila (rock goldenrod). Associated rare species in the southern San Francisco Mountains include Eriogonum soredium (Frisco buckwheat) and Lepidium ostleri (Ostler’s peppergrass), which generally grow on the same substrate in similar but more open habitats adjacent to Frisco clover. Flowering occurs from late May to June, followed by fruit set in June through July (Welsh et al. 2008). No other information is available on the life history of this species.
Movement / Home Range
Frisco clover is historically and currently known from five populations on private, SITLA, BLM, and USFS lands in Beaver and Millard Counties, Utah (Kass 1992; Evenden 1998; Evenden 1999; Miller 2010c; Miller 2010e, pers. comm.; Roth 2010).
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