(bitter fleabane)
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Photo of Erigeron acris by Jacob Frank
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Erigeron acris is a tall herb in the aster family (Asteraceae), with an open, much-branched
inflorescence of white to lilac flowers.
Erigeron acris occurs in river bars and terraces and occasionally in open forested sites. Plants grow 20-60 cm tall from fibrous roots. Plants have both basal and stem leaves, stem leaves are alternate (as is the case for all members of this genus in Denali). Leaves are
oblanceolate to
lanceolate, margins
entire or irregularly
toothed. The flowering heads form an open, much branched
inflorescence (
corymb),
peduncles spreading or ascending, 1-35 heads a plant. Like all members of the aster family, each flowering head is composed of many reduced flowers. The
ray florets at the edge of the flower are white to purplish, the petals not much longer than the central yellow
disc florets. Fruits are plumed single-seeded
achenes. This species of
Erigeron is distinguished from other species in the park by the branched, flat-topped
inflorescence and
glandular pubescence on the
involucrum.
Erigeron acris is annual, biennial or a short-lived perennial. It flowers in mid-summer.
Plants are
monoecious.
Erigeron acris is insect pollinated. The fruits are plumed, allowing the seeds to be carried by the wind.
Erigeron acris is a widespread circumboreal species. In Alaska, this species occurs south of the Brooks Range, apparently not reaching the west coast. In Denali, bitter fleabane is common in the northwestern boreal lowlands of the Park, and also occurs (less commonly) south of the Alaska Range crest.
Details are shown in the Plots & Charts found at right, depicting recent Denali data.
Erigeron acris grows at low elevations, all plants found at below 500 m. All but two of the plants found in Denali were on slopes below 5 degrees.
Details are shown in the Plots & Charts found at right. For more on how to interpret these figures, visit Understanding Data Presented.
Erigeron acris prefers sandy or rocky soils, found along creeks, in willow thickets, meadows, forest edges and in disturbed areas.
Wide ranging; somewhat wet to dry sites.
