Juncus patens
Spreading rush, Spreading Rush
(c) Ken-ichi Ueda, some rights reserved (CC BY) · licence
Family: Juncaceae · Type: Grass · Native
Juncus patens (Spreading rush) is a native California grass in the Juncaceae family, recognized by distinctive blue-gray grooved stems and prominent lateral bract.
Spreading rush is a California native perennial found in the Klamath Ranges, northern California Coast Ranges, northern Sierra Nevada foothills, Central Western California, southern California coastal areas, Channel Islands, and western Transverse Ranges in marshy places, creeks, and seeps at elevations below 1,600 meters. Its distinctive blue-gray-green stems are distinctly grooved and grow 30 to 105 centimeters tall, forming dense tufted clusters. Flower clusters appear laterally, with dark brown to black leaf sheaths that transition to green or pale brown at the upper half. The plant produces small flowers with narrow, spreading perianth parts measuring 2.2 to 3.4 millimeters long, with sepals slightly longer than petals. Tiny seeds measuring 0.4 to 0.6 millimeters are asymmetric and weakly net-veined with minute appendages.
Identification and appearance
Key characters: 61 sympatric species; distinctive blue-gray grooved stems and prominent lateral bract
Habitat and range
Habitat: Marshy places, creeks, seeps
Elevation: < 1600 m
California counties: Humboldt, Mendocino, Shasta, Butte, Marin, San Francisco, San Mateo, Santa Cruz, Sonoma, Santa Barbara, Alameda, Contra Costa, Lake, Monterey, Napa, San Luis Obispo, Santa Clara, Siskiyou, Orange, Los Angeles, San Diego, Ventura, Riverside, Tehama, Colusa, Yolo, Solano, Nevada, Trinity, Mariposa, Placer, Sacramento
Outside California: to southern Washington, Mexico
How to tell it apart
vs Schoenoplectus: Juncus has leaf blades present; Schoenoplectus is leafless with only bladeless sheaths at base.; vs Carex: Juncus has round or flattened stems; Carex has triangular stems you can feel.; vs Luzula: Run finger along leaf edge - smooth = Juncus, hairy = Luzula.; vs Elegia: Juncus has small individual flowers; Elegia has showy papery bracts and branching structure.; vs Cyperus: Juncus has round stems and capsules; Cyperus has triangular stems and lens-shaped achenes.
Frequently asked questions
Is Juncus patens native to California?
Yes. Juncus patens is native to California (recorded as native).
Where in California does Juncus patens grow?
Juncus patens occurs in Humboldt, Mendocino, Shasta, Butte, Marin, San Francisco, San Mateo, Santa Cruz and other counties, at elevations of < 1600 m.
What plant family does Juncus patens belong to?
Juncus patens is in the Juncaceae family, genus Juncus.
What habitat does Juncus patens grow in?
Juncus patens grows in Marshy places, creeks, seeps.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.