Scirpus diffusus
Diffuse rush
(c) Santiago Martín-Bravo, some rights reserved (CC BY) · licence
Family: Cyperaceae · Type: Grass · Native
Scirpus diffusus (Diffuse rush) is a native California grass in the Cyperaceae family, recognized by head-like clusters and bristles not exceeding bracts.
Diffuse rush is a California native perennial found in the Klamath Ranges, southern Cascade Range, and Sierra Nevada in meadows, marshes, and streambanks at elevations of 200 to 2,400 meters. Flowering in July, this plant produces small spikelets in head-like clusters with green to brown or nearly black flower bracts. Growing with spreading stems 70 to 80 centimeters tall and 2 to 5 millimeters in diameter, it has a distinctive three-angled stem and long rhizome. Its leaves are wide, measuring 5 to 8 millimeters across, with no ligule and supporting delicate flower clusters. The fruit is tiny, measuring 0.9 to 1.3 millimeters long and three-angled, with perianth bristles that may be curled or straight.
Identification and appearance
Key characters: 4 sympatric species; key features are head-like clusters and bristles not exceeding bracts
Habitat and range
Habitat: Meadows, marshes, streambanks
Elevation: 200-2400 m
California counties: Butte, Tulare, Fresno, Plumas, Nevada, Tuolumne, Lake, Tehama, Colusa, Calaveras, Humboldt, El Dorado, Madera, Placer
Bloom period
Scirpus diffusus blooms Jul.
How to tell it apart
vs Cyperus: Scirpus has drooping branched clusters, Cyperus has flat umbrella-like bracts radiating from a central point.; vs Schoenoplectus: Scirpus clusters are openly branched and spreading, Schoenoplectus has dense compact clusters.; vs Carex: Scirpus has perfect flowers in branched clusters, Carex has separate male/female spikes.; vs Bolboschoenus: Scirpus lacks underground tubers entirely, Bolboschoenus has firm tubers.; vs Juncus: Scirpus has obvious flowers in spikelets, Juncus has tiny flowers with visible petals/sepals.
Frequently asked questions
Is Scirpus diffusus native to California?
Yes. Scirpus diffusus is native to California (recorded as native).
When does Scirpus diffusus bloom?
Scirpus diffusus blooms Jul.
Where in California does Scirpus diffusus grow?
Scirpus diffusus occurs in Butte, Tulare, Fresno, Plumas, Nevada, Tuolumne, Lake, Tehama and other counties, at elevations of 200-2400 m.
What plant family does Scirpus diffusus belong to?
Scirpus diffusus is in the Cyperaceae family, genus Scirpus.
What habitat does Scirpus diffusus grow in?
Scirpus diffusus grows in Meadows, marshes, streambanks.
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.