Willamette daisy is a tap-rooted perennial species growing from a crown or slightly branched caudex. Stems are decumbent, moderately strigose, 15-70 cm tall, and often purplish at the base. The leaves are numerous, sparsely to moderately strigose, linear or linear-lanceolate, the basal leaves and most of the cauline leaves triple-nerved. Basal leaves are up to 25 cm long, including the long petiole, and 1 cm wide, with cauline leaves becoming gradually reduced above. Flowering heads number from 1-20, the disk 0.8-1.5 cm wide, the involucre 0.35-0.6 cm high, and the 20-50 blue-purple to pale pink ray flowers 0.6-1.2 cm long by 0.1-0.2 cm wide. The pappus consists of 1216 fragile bristles.
The Willamette daisy is found in seasonally-wet prairies and drier upland prairie sites, where woody cover is nearly absent and herbaceous vegetation tends to be low in stature.
Limiting factors
This species is endemic to the Willamette Valley. The Willamette daisy is threatened by habitat loss and habitat degradation due to lack of fire and encroachment of woody plants, loss of floodplain function, and displacement by invasive plants. Issues of few, mostly small populations may also be important.
Data gaps
Improve understanding of reproductive biology. Conduct long-term demographic monitoring to determine population dynamics and optimal fire regimes to maintain habitat and populations. Investigate genetics and evaluate inbreeding depression; develop seed transfer and augmentation guidelines. Describe pollinator associations and status. Evaluate the effects of voles on this species. Model predicted effects of climate change.
Conservation actions
Continue prairie management where extant populations occur to maintain and expand populations. Identify suitable protected sites for introductions. Maintain or restore hydrology. Control invasive and woody plants through use of well-timed mowing, prescribed fire, and selected herbicide use, as appropriate. Collect seeds for storage and grow out for outplanting. Monitor populations.
Key reference or plan
A Critical Habitat Designation for Willamette Daisy was issued by the U.S. Fish and Wildlife Service in 2006. 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 Willamette daisy.
