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Cook's lomatium

Photo of Cook's Lomatium

Scientific name: Lomatium cookii

Status: Endangered

Critical Habitat: Designated

Listing: Cook's lomatium was listed as endangered in 2002 (U.S. Fish and Wildlife Service 2002). Critical habitat was designated in July 2010.

Potential Range Map 

  • Description and Life History

    Cook's lomatium is a small perennial plant (1.5-5 dm or 0.5-1.6 ft tall) in the parsley family (Apiaceae), with a slender, twisted taproot. The taproot often branches at ground level, forming multiple stems. An umbel of pale yellow flowers develops boat-shaped fruits 8-13 mm (0.3-0.5 in) long with thickened margins. The leaves are smooth, finely dissected, and strictly basal. Flowering typically occurs from mid-March through mid-May.


    This plant occurs only where soil types have a hard pan or clay pan layer close to the soil surface, creating seasonally wet soils and vernal pools. The Agate Desert is characterized by shallow, Agate-Winlow soils, a relative lack of trees, sparse prairie vegetation, and agate on the soil surface. Associated species in the Agate Desert include meadowfoams (Limananthes floccosa ssp. grandiflora - also proposed for listing- and L. f. ssp. floccosa), Plagiobothrys bracteatus (no common name), and Navarretia spp. Associated species at French Flat include California oatgrass (Danthonia californica), Plagiobothrys bracteatus, shaggy horkelia (Horkelia congesta), short-stemmed star tulip (Calochortus uniflorus), and sedge-leaf buckbrush (Ceanothus cueatus).

    Reasons for Decline

    Industrial, commercial, and residential development, road and power-line construction and maintenance, livestock grazing, agricultural conversion, weed competition, mowing, and roadside spraying have all contributed to the decline of this species. In Josephine County, Cook's lomatium is also threatened by gold mining, logging, fire suppression, and uncontrolled off-road-vehicle use.


    This species is known from the Agate Desert near Medford, Jackson County, Oregon and French Flat in the Illinois Valley in Josephine County, Oregon on land owned by The Nature Conservancy (Agate Desert Preserve), Jackson County, Oregon Department of Fish and Wildlife, City of Medford, Oregon Department of Transportation, Bureau of Land Management (French Flat), and private landowners.

    Conservation Measures

    On lands managed by the U.S. Bureau of Reclamation, the Oregon Department of Transportation, the Oregon Department of Fish and Wildlife, and The Nature Conservancy, Cook’s lomatium receives protection from developmental related impacts. These agencies and organizations protect the species and manage their lands to benefit the species’ continued existence.


    U.S. Fish and Wildlife Service. November 7, 2002. Endangered Status for the Plants Lomatium cookii (Cook's lomatium) and Limnanthes floccosa ssp. grandiflora (Large-Flowered Wooly Meadowfoam) in Oregon. Final Rule. Federal Register 67, No 216.


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