Erigeron decumbens var. decumbens

Common Names:
Willamette daisy, Willamette Valley daisy, Williamette fleabane
Growth Habit:
CPC Number:
Profile Contributors:
Edward Guerrant, Ph.D.
Fully Sponsored

Reference Links

ITIS - Tropicos - USDA Plants - Fish & WildLife

Participating Institutions

The following Participating Institutions are custodians for this species in the CPC National Collection:
Rae Selling Berry Seed Bank & Plant Conservation Programs

The conservation of Erigeron decumbens var. decumbens is fully sponsored.
Edward Guerrant, Ph.D. contributed to this Plant Profile.


Today, less than one present of Prairie land in the Willamette Valley remains in western Oregon and southwestern Washington. Consequently, the once common Willamette daisy (Erigeron decumbens ssp. decumbens) has nearly become extinct.

Not seen since 1934, Erigeron decumbens ssp. decumbens was thought extinct until 1980, when two populations were discovered. Although more populations have subsequently been found, this species continues to be at risk. In 1986 the largest population ever known (>6000 plants) was destroyed by plowing. The current 18 populations contain a mere 7500 plants, and only 4 of these remaining populations are on federal or city land and therefore legally protected from development.

Post-colonization land use practices are responsible for the destruction and fragmentation of the oak-savanna ecosystem. Both flooding and occasional fires helped to preserve the prairie habitat. The Native Americans that initially made the Willamette Valley their home managed prairies by setting fires in order to increase the abundance of food plants and for ease of hunting. This kept ash, rose, blackberry, conifers and other woody species from invading.

Since European settlement, vast tracts of Willamette Valley Prairie have been converted to agricultural production or human habitation. Due to fire suppression efforts, much of the remaining areas have been converted to dense thickets of brush or trees. The Willamette daisy has not been found in any areas currently grazed or farmed, but is sometimes found in places that were formerly grazed or farmed, providing encouragement that restoration efforts could be successful.

Distribution & Occurrence


Conservation, Ecology & Research