Photo © Robert Moseley CLICK PHOTO FOR A LARGER IMAGE

Rhynchospora alba (L.) Vahl

White Beakrush

Cyperaceae (Sedge family)

General Description: A grass-like perennial, 15-50 cm tall that grows in densely tufted clumps. The thin stems are triangular and solid. It has several leaves, the lowest often more or less reduced to scales, the others slender and no more than about 1 mm wide. The inflorescence has 1-3 compact head-like clusters that are whitish in appearance, especially at anthesis. They are mostly 5-15 mm wide, with the terminal cluster of spikelets larger than the others. Achenes are 1.5-2 mm long and capped by an elongate, narrow tubercle. They are subtended by 10-12 well developed, minutely barbellate perianth bristles.

Illustration.

Field Identification Tips: The inflorescence's whitish appearance is a good field character.

Phenology: Flowers in July-August.

Similar Species: The whitish, head-like inflorescence, fruits with bristles, and the lack of a perigynia distinguish R. alba from all sedge (Carex) species.

Photo © Robert Moseley CLICK PHOTO FOR A LARGER IMAGE

Habitat: Bogs, fens, and other very wet places at moderate and low elevations.

Global Distribution: Interruptedly circumboreal, but not at the highest latitudes. In North America it ranges from Newfoundland to North Carolina, inland to the Great Lakes region. The range is continuous across southern Canada to the Pacific, where it occurs from the Alaskan panhandle to central California. It is chiefly found west of the Cascade-Sierran summits, but also inland in northern Idaho.

Idaho Distribution: Boundary, Bonner, and Kootenai counties in the Panhandle region, and at Warm Lake in central Valley County.

References:

Bursik, R. J. 1992. Field investigations of sensitive plant taxa occurring on the Priest Lake Ranger District, Kanisku National Forest, Idaho Panhandle National Forests. Unpublished report prepared for the Panhandle National Forests by the Idaho Department of Fish and Game, Conservation Data Center, Boise. 141 pp. plus appendices.

Moseley, R. K. 1989. Field investigations of 16 rare plant taxa occurring in wetlands on the Bonners Ferry Ranger District, Idaho Panhandle National Forest. Unpublished report prepared for the Panhandle National Forests by the Idaho Department of Fish and Game, Conservation Data Center, Boise. 75 pp. plus appendices.