White Top Aster

The Colombian white top aster (Sericocarpus rigidus) is a native perennial plant in the Pacific Northwest, found from Vancouver Island in British Columbia south to Oregon and Washington, particularly west of the Cascade Mountains. This "vulnerable" species features clustered white flowers from July to September in its natural habitat of prairies and open grasslands. Major threats include habitat loss from invasive plants like Scotch broom and reduced natural fire activity, which allows Douglas fir to encroach on its grassland home. 

Not what the WSNPS suggests:

Sericocarpus rigidus

Columbian white-topped aster, Columbian white top aster, rigid white-topped aster.

Taken 10/04/25

Photo David Giblin.

https://burkeherbarium.org/imagecollection/taxon.php?Taxon=Sericocarpus+rigidus 

General:

Nearly glabrous perennial from slender, creeping rhizomes, the stem 1-3 dm. tall, usually simple and unbranched up to the inflorescence.

Leaves:

Lowermost leaves reduced and early-deciduous, the largest ones a little above the base, 2.5-3.5 cm. long and 5-9 mm. wide, oblanceolate, sessile; those leaves above numerous and gradually reduced; often scabrous on the midrib beneath, and with stiff, short hairs on the margins.

Flowers:

Heads in a close terminal cluster; involucre 7-9 mm. high, narrow, the bracts imbricate, white and papery below with a light green herbaceous tip; rays usually 2, shorter than the capillary pappus, 1-3 mm. long, white; disk flowers 9-21, pale yellowish, with purple anthers.