(Map may reflect historical as well as recent sightings)
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
Description and Life
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.
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.
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.