Erigeron poliospermus is a species of flowering plant in the family Asteraceae known by the common names gray-seeded fleabane, purple cushion fleabane, and hairy-seed fleabane. Native to western North America, it is mainly found to the east of the Cascade Range in Washington, Oregon, and Idaho.Biota of North America Program 2014 county distribution map
Description Erigeron poliospermus is a small perennial herb rarely more than tall, producing a woody taproot. Leaves arise basally and are linear-oblanceolate to spatulate, up to 8 cm long and 12 mm wide, and are covered with long protruding hairs. The plant usually produces single (rarely up to 3) flower heads per stem, which arises basally and is hairy and is leafless or may bear a few very reduced leaves. Each head has 15–45 pink, purple, or white ray florets surrounding numerous yellow disc florets. The ray florets are lacking in var. disciformis. The involucre bracts, long, are more or less the same length and are sparsely to densely white-hairy. Seeds are borne on achenes densely covered with long silky hairs Burke Herbarium Image Collection| http://biology.burke.washington.edu/herbarium/imagecollection/taxon.php?Taxon=Erigeron poliospermus and are presumably wind dispersed.
The somewhat similar Erigeron pumilus is usually taller and shaggier in general appearance and has much more prominent leaf-like bracts scattered up a branched flower stem and usually multiple flowers per stem and narrower basal leaves.Cronquist, A.J. 1994. Asterales. 5: 1–496. In A.J. Cronquist, A. H. Holmgren, N. H. Holmgren, J. L. Reveal & P. K. Holmgren (eds.) Intermountain Flora. Hafner Pub. Co., New York.Scoggan, H. J. 1979. Dicotyledoneae (Loasaceae to Compositae). Part 4. 1117–1711 pp. In Flora of Canada. National Museums of Canada, Ottawa.
Habitat Erigeron poliospermus grows in desert, scrub and rocky habitats below , and is occasionally found at higher elevations.Biota of North America Program 2014 county distribution map It is common on the Columbia Plateau in thin rocky soils above basalt bedrock.
Varieties Erigeron poliospermus var. cereus Cronquist - Washington Erigeron poliospermus var. disciformis (Cronquist) G.L.Nesom - Washington, OregonNesom, Guy L. 2004. Sida 21(1): 24 Erigeron poliospermus var. poliospermus - British Columbia, Washington, Idaho, Oregon
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