Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to northern Oregon, east to the northern Great Plains, Great Lakes region, and northeastern North America.
Habitat: Lake shores and coastal bogs to montane marshes and meadows; in Washington, from near sea level to about 5000 feet elevation.
Flowers: June-August
Origin: Native
Growth Duration: Perennial
Conservation Status: Not of concern
Pollination: Wind
Somewhat tufted perennial with widespread rhizomes, the stems terete, about 1 mm. in diameter, 5-30 cm. tall.
Sheaths tight, truncate to rounded, usually with a vestige of a blade.
Inflorescence apparently lateral, the involucral bract terete, erect, sharp-pointed, at least half as long as the stem and sometimes exceeding it; inflorescence a tight to open panicle up to 2 cm. long, 7- to 15-flowered; perianth 3-4 mm. long, the 6 segments sub-equal, greenish, lanceolate; stamens 6, the anthers shorter than the filaments.
Capsule ovoid to obovoid, firm, slightly shorter than the perianth.
PNW Herbaria: Specimen records of Juncus filiformis in the Consortium of Pacific Northwest Herbaria database
WA Flora Checklist: Juncus filiformis checklist entry
OregonFlora: Juncus filiformis information
E-Flora BC: Juncus filiformis atlas page
CalPhotos: Juncus filiformis photos