[Daisies and Fleabanes: The Genus Erigeron in the Columbia River Gorge of Oregon and Washington]

Annual Fleabane

Erigeron annuus

Flower heads of Annual Fleabane: Erigeron annuus - Annual Fleabane: Erigeron annuus

The photo at left of shows the flower heads of annual fleabane as seen from the banks of Gillette Lake, several miles north of Bonneville Dam in the western Columbia River Gorge........September 12, 2007. The photo at right shows a close-up of the flower heads of annual fleabane as observed along equestrian trails high in Beacon Rock State Park.......November 13, 2018.

Characteristics:

Annual fleabane as its name implies is an annual herb, or occasionally a biennial. Its one to several stems are erect, measuring from 60-150 cm high. The stems are often branched. The herbage of the stems usually consists of long, spreading hairs below the inflorescence. The basal leaves are oblanceolate to broadly ovate, and are prominent early in the growing season, but become deciduous as blooming season begins. The stem leaves are broadly lanceolate with coarsely toothed margins. The lower stem leaves measure from 6-12 cm long.

The open inflorescence is large and leafy. The hemispheric involucre is 3-5 mm high and finely glandular and sparsely long-haired. The 80-125 rays are white (occasionally light blue or lilac) and measure to 10 mm long and from 0.5-1 mm wide.


Habitat:

Annual fleabane is a weedy species found in moist disturbed ground, including gardens, ditches, roadsides, trails and waste areas.


Range:

Originally from Europe, annual fleabane may be found across much of the United States and southern Canada.

In the Columbia River Gorge, annual fleabane is found between the elevations of 100'-2400' between Troutdale, Oregon and Hood River, Oregon.


Stem leaf of Annual Fleabane: Erigeron annuus

Underside of a stem leaf of Annual Fleabane: Erigeron annuus

The photos above show the upper (top) and lower (bottom) surfaces of a leaf from mid-stem of annual fleabane. Note the few, coarse teeth on the margin of the blade as well as the numerous spreading hairs from both surfaces.

Inflorescence and upper stem leaves of Annual Fleabane: Erigeron annuus
The photo above of shows a sideview of the upper stem and inflorescence of annual fleabane as seen from the banks of Gillette Lake, several miles north of Bonneville Dam in the western Columbia River Gorge.........September 12, 2007.

Involucral bracts of Annual Fleabane: Erigeron annuus
A view of the involucres of annual fleabane from the Columbia River Gorge.

Paul Slichter