Bradshaw's lomatium was federally listed as endangered without critical habitat in 1988 (U.S. Fish and Wildlife Service 1988). A recovery plan was published in 1993 (U.S. Fish and Wildlife Service 1993).

Description and Life History

Bradshaw's lomatium is perennial herb in the parsley family (Apiaceae). It can reach 20-50 cm (8-20 in) in height, with mature plants having only 2-6 leaves. Leaves are chiefly basal and are divided into very fine, almost threadlike, linear segments. The yellow flowers are small, measuring about 1 mm (0.05 in) long and 0.5 mm (0.025 in) across, and are grouped into asymmetrical umbels. Each umbel is composed of 5-14 umbellets, which are subtended by green bracts divided into sets of three. This bract arrangement differentiates Bradshaw's from other lomatiums. Bradshaw's lomatium blooms during April and early May, with fruits appearing in late May and June. Fruits are oblong, about 1.2 cm (0.5 in) long, corky and thick-winged along the margin, and have thread-like ribs on the dorsal surface. This plant reproduces entirely from seed. Insects observed to pollinate this plant include a number of beetles, ants, and some small native bees.

Habitat

The majority of Bradshaw's lomatium populations occur on seasonally saturated or flooded prairies, adjacent to creeks and small rivers in the southern Willamette Valley. Soils at these sites are dense, heavy clays, with a slowly permeable clay layer located 15-30 cm (6-12 in) below the surface. This clay layer results in a perched water table during winter and spring, and is critical to the wetland character of these grasslands, known as tufted hair-grass (Deschampsia cespitosa) prairies. Bradshaw's lomatium occurs on alluvial (deposited by flowing water) soils. The species occurs on soils in the Wapto, Bashaw and Mcalpin Series (NRCS mapped soil unit STATSGO 81).

Reasons for Decline

Endemic to and once widespread in the wet, open areas of the Willamette Valley of western Oregon, Bradshaw's lomatium is limited now to a few sites in Lane, Marion, and Benton Counties. Most of its habitat has been destroyed by land development for agriculture, industry, and housing. In addition, water diversions and flood control structures have changed historic flooding patterns, which may be critical to seedling establishment. Reductions in natural flooding and fire cycles also permit invasion of trees and shrubs, and eventual conversion of wet prairies to woodlands.

Range

Bradshaw's lomatium currently extends from Clark county, Washington, to the southern end of the Willamette Valley, Oregon. The greatest concentrations of remaining sites where plants occur is in and adjacent to the Eugene, Oregon metropolitan area.

References and Links

U.S. Fish and Wildlife Service. 1988. Final Listing: Endangered Status for Lomatium bradshawii (Bradshaw's Lomatium). Federal Register 53:38448-38451. https://ecos.fws.gov/docs/frdocs/1988/88-22327.pdf

U.S. Fish and Wildlife Service. 1993. Lomatium bradshawii (Bradshaw's lomatium) Recovery Plan. Portland, Oregon. 47 pp. http://ecos.fws.gov/docs/recovery_plans/1993/930813b.pdf