Juncus cooperi
Cooper's rush
(c) Bob Miller, some rights reserved (CC BY) · licence
Family: Juncaceae · Type: Grass · Native
Conservation status: CNPS 4.3
Juncus cooperi (Cooper's rush) is a native California grass in the Juncaceae family, recognized by . Key features: desert alkaline habitat, short stiff sharp leaves, spongy roots.
Cooper's rush is a native perennial found in the Desert bioregion in alkaline places at elevations below 700 meters. Flowering time not specified, this rush produces pale green-straw-colored flowers with white bractlets in small clusters. Growing in dense tufts 40 to 80 centimeters tall with a short, thick, many-branched rhizome, it forms large spongy roots. Its basal leaves are short, stiff, and cylindrical with sharp tips, with the lowest bract resembling the stem and extending beyond the flowering clusters. The fruit is narrowly oblong and three-angled, with seeds featuring a conspicuous white ridge and minute unequal appendages.
Identification and appearance
Key characters: 16 sympatric species. Key features: desert alkaline habitat, short stiff sharp leaves, spongy roots
Habitat and range
Habitat: Alkaline places
Elevation: < 700 m
California counties: Imperial, Inyo, Riverside, San Bernardino, San Diego, Santa Barbara
Outside California: Nevada, Mexico
Conservation status
CNPS 4.3
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 cooperi native to California?
Yes. Juncus cooperi is native to California (recorded as native).
Where in California does Juncus cooperi grow?
Juncus cooperi occurs in Imperial, Inyo, Riverside, San Bernardino, San Diego, Santa Barbara, at elevations of < 700 m.
What plant family does Juncus cooperi belong to?
Juncus cooperi is in the Juncaceae family, genus Juncus.
Is Juncus cooperi rare or endangered?
Juncus cooperi carries California Rare Plant Rank 4.3, state rank S3.
What habitat does Juncus cooperi grow in?
Juncus cooperi grows in Alkaline places.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
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.