Juncus effusus subsp. pacificus
Pacific rush, Pacific Rush
Photo: parent species Juncus effusus · (c) Douglas Goldman, some rights reserved (CC BY-SA) · licence
Family: Juncaceae · Type: Grass · Native
Juncus effusus subsp. pacificus (Pacific rush) is a native California grass in the Juncaceae family, recognized by native status, dark sheaths, and pressed perianth.
Pacific rush is a California native perennial found in the California Floristic Province in seeps, shores, marshes, and generally damp sunny ground at elevations below 2,500 meters. Flowering from late spring to summer, this rush produces pale flowers in open, ascending branch clusters. Growing to 112 centimeters tall with stems 2 to 3 millimeters wide, it has distinctive dark brown to nearly black leaf sheaths with strongly converging veins and thickened, overlapping margins. Its leaf sheaths are generally 6 to 19 centimeters long, with a broadly asymmetrical summit and papillate surface. The fruit is a small oblong capsule approximately 2 to 2.4 millimeters long with three inner chambers.
Identification and appearance
Key characters: 74 sympatric species; key features are native status, dark sheaths, and pressed perianth
Habitat and range
Habitat: Seeps, shores, marshes, generally damp sunny ground
Elevation: < 2500 m
California counties: Humboldt, El Dorado, Butte, Contra Costa, Fresno, Lake, Marin, Mendocino, Monterey, Plumas, San Joaquin, San Mateo, Santa Clara, Santa Cruz, Siskiyou, Sonoma, Trinity, Tuolumne, Yuba, Inyo, Kern, Santa Barbara, Amador, Shasta, Tulare, Placer, Mariposa, Tehama, Glenn, Nevada, Napa, Stanislaus, Riverside, Alameda, Sacramento, Colusa, San Luis Obispo, San Francisco, Del Norte, Calaveras, San Diego, Madera
Outside California: to British Columbia
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 effusus subsp. pacificus native to California?
Yes. Juncus effusus subsp. pacificus is native to California (recorded as native).
Where in California does Juncus effusus subsp. pacificus grow?
Juncus effusus subsp. pacificus occurs in Humboldt, El Dorado, Butte, Contra Costa, Fresno, Lake, Marin, Mendocino and other counties, at elevations of < 2500 m.
What plant family does Juncus effusus subsp. pacificus belong to?
Juncus effusus subsp. pacificus is in the Juncaceae family, genus Juncus.
What habitat does Juncus effusus subsp. pacificus grow in?
Juncus effusus subsp. pacificus grows in Seeps, shores, marshes, generally damp sunny ground.
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.