Photo © Peter Lesica CLICK PHOTO FOR A LARGER IMAGE

Eriophorum viridicarinatum (Engelm.) Fern.

Green Keeled Cotton-grass

Cyperaceae (Sedge family)

General Description: Stems widely spaced from an extensive creeping rhizome, from 20 to 60(90) cm tall. The long, largely flat, sheathing basal and stem leaf blades are 2-6 mm wide. The stem is terminated by 2-8, somewhat nodding spikelets borne in an umbel-like inflorescence. Scales are blackish-green with a prominent pale midrib that reaches the tip of the scale. Numerous prominent, white perianth bristles greatly exceed the scales and achenes and give the appearance of a cotton ball attached to the top of the plant.

Illustration.

Field Identification Tips: The cotton-grasses are characterized by the long, whitish, cottony perianth bristles that completely obscure the flower scales, bracts, and fruits. Eriophorum viridicarinatum often forms large colonies from creeping rhizomes.

Phenology: Flowers June through July.

Similar Species: Eriophorum viridicarinatum closely resembles E. polystachion, but has scales that are consistently blackish-green with a well-developed, notably paler midrib that tends to be expanded distally and reaches to the tip of the scale. Eriophorum polystachion has tawny to brownish or blackish-green scales with a slender midrib that is attenuated and does not reach the tip of the scale.

Photo © Robert Bursik CLICK PHOTO FOR A LARGER IMAGE

Habitat: Bogs, peatlands, and wet meadows.

Global Distribution: From Newfoundland to Alaska, south to New York, Michigan, Colorado, Wyoming, Washington, Idaho, and Montana.

Idaho Distribution: Boundary and Bonner counties in the Panhandle region, and Valley, Fremont, and Teton counties to the south and east.

References:

Fertig, W., and G. Jones. 1992. Plant communities and rare plant species of the Swamp Lake Botanical Area, Clark's Fork Ranger District, Shoshone National Forest. Challenge Cost-Share Agreement, Shoshone National Forest. 113 pp.

Moseley, R. K., R. Bursik, and M. Mancuso. 1991. Floristic inventory of wetlands in Fremont and Teton counties, Idaho. Unpublished report prepared for the Panhandle National Forests by the Idaho Department of Fish and Game, Conservation Data Center, Boise. 60 pp. plus appendices.