White rock larkspur – State Wildlife Action Plan

White rock larkspur

Photo Credit: Oregon Department of Agriculture

White rock larkspur is a slender perennial species 20-60 cm tall that grows from a cluster of tubers. Leaves are numerous and evenly distributed on the stem, with long petioles and lobed blades. The inflorescence is a narrow raceme bearing 6-30 nonglandular flowers. The sepals are white to cream, sometimes slightly greenish blue on the back and greenish at the tip, and cupped forward or spread laterally. The lower petals are white or faintly bluish tinged and long-hairy over the entire surface, the upper petals bluish to lavender-tipped. The follicles are 0.8-1.2 cm long, puberulent, and non-glandular.

Overview

  • Species Common Name White rock larkspur
  • Species Scientific Name Delphinium leucophaeum
  • Federal Listing Status Species of Concern
  • State Listing Status Endangered

Ecoregions

Special needs

White rock larkspur occurs in well-drained areas within open lowland prairies, in dry roadside ditches, along river banks and bluffs, and in open areas atop basaltic shelves. This species prefers loose, shallow soils with high organic matter content. Associated with oak woodlands.

Limiting factors

A key threat is habitat loss due to urban and agricultural development. Fire suppression and invasive vegetation encroachment in the understory can degrade remaining habitat. Herbicide use and other roadside maintenance activities can also harm this species. White rock larkspur persists in low numbers in small populations. The species is moderately vulnerable to climate change, primarily based on its association with Willamette Valley oak savannas and its sensitivity to competition.

Conservation actions

Restore habitat using site-appropriate methods: control encroaching trees and shrubs and control key invasive plants. Monitor populations. Identify suitable habitat for introductions. Conduct ex-situ seed/plug production for introduction and augmentation efforts.

Key reference or plan

A U.S. Fish and Wildlife Service Recovery Plan for prairie species of western Oregon and southwestern Washington (https://ecos.fws.gov/docs/recovery_plan/100629.pdf) was released in 2010 and addresses conservation needs of white rock larkspur. Marshall, DA. 2025. 2025 listing status assessment for Delphinium leucophaeum (White rock larkspur). Oregon Department of Agriculture, Salem, Oregon.