Douglas' aster from Dalton Point, Columbia River Gorge................October 12, 2006. Note that the outer edges of the bracts (at least at their bases) are whitish, a good characteristic to help ID this species.
Douglas' aster is a rhizomatous perennial wildflower with erect, usually unbranched stems to 130 cm high. It is highly variable in appearance and may resemble both leafy aster and Eaton's aster. The lower leaves are oblanceolate, tapering to a winged petiole. The leaves of mid-stem are lance-shaped and range from 7-13 cm long and 1-2 cm wide. The blades are smooth and hairless with toothed margins above mid-blade.
The inflorescence is a cymose panicle with several to many flower heads which are each 2-4 cm wide. The 20-30 rays are violet and about 1 cm long and surround the yellow to reddish-purple disk flowers. The involucre is about 5-6 mm long with linear bracts, the outer bracts sometimes leaf-like at the tip. The bracts loosely overlap and may be pressed down or spreading and green at the tip with yellow to brown bases and hairy margins. Visible with a hand lens, each bract has a thin transparent margin.
Douglas' aster is a wildflower of streambanks and other moist places from low elevations near the seacoast to moderate elevations in mountain woodlands.
Douglas' aster is found from coastal Alaska south to coastal California and east to Alberta, Montana, northern Idaho and northeastern Oregon. It is most common west of the Cascade Mts.
Douglas' aster as seen along the Columbia River shoreline on a low island in the McNary National Wildlife Refuge north of Richland, Washington............October 2, 2012. The narrow leaves are reminiscent of western mountain aster (Symphyotrichum spathulatum) which can also be found in the same habitat, but that latter species lacks the white margins at the base of the involucral bracts and it does not have teeth on its narrow leaves..