Bolboschoenus fluviatilis
River bulrush
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Family: Cyperaceae · Type: Grass · Native
Bolboschoenus fluviatilis (River bulrush) is a native California grass in the Cyperaceae family, recognized by freshwater habitat, large size, sinking fruits, and highly branched inflorescence.
River bulrush is a native perennial found in northern California coastal regions, northern Sierra Nevada, Sacramento Valley, central Coast, and North Coast Ranges in fresh water marshes at elevations below 1,300 meters. Flowering during summer, this plant produces yellow-anthered flowers in clusters of 10 to 40 spikelets, each 10 to 25 millimeters long. Growing to 1 to 2 meters tall with sturdy stems 5 to 15 millimeters in diameter, it develops robust, upright culms in aquatic environments. Its leaf sheaths are papery and veined, with blade widths ranging from 7 to 22 millimeters, and the leaves emerge from the water with distinctive structural integrity. The fruit is strongly three-sided, 3.8 to 5.5 millimeters long, and uniquely adapted to sink in water, with small, solid wall cells.
Identification and appearance
Key characters: 3 sympatric species; key features are freshwater habitat, large size, sinking fruits, and highly branched inflorescence
Habitat and range
Habitat: Uncommon in California. Fresh water marshes
Elevation: < 1300 m
California counties: Sutter, Plumas, San Joaquin, Santa Cruz, Lake, Sonoma, Yolo, Alameda, San Mateo, Napa, Butte, Glenn, Modoc, Lassen, San Luis Obispo, Placer, Colusa, Sacramento, Solano, Shasta
Outside California: temperate North America except most of southern United States
Bloom period
Bolboschoenus fluviatilis blooms Summer.
How to tell it apart
vs Schoenoplectus: Dig for tubers - Bolboschoenus has firm tubers, Schoenoplectus has only fibrous roots or rhizomes.; vs Carex: Bolboschoenus flowers are in rounded spikelets, Carex has separate male/female spikes or combined in same spike.; vs Scirpus: Bolboschoenus has firm underground tubers, Scirpus lacks tubers entirely.; vs Cyperus: Bolboschoenus has three-angled stems, Cyperus typically has flat leaf-like bracts radiating umbrella-like at top.; vs Sporobolus: Bolboschoenus stems are three-angled and solid, grass stems are round and hollow with nodes.
Frequently asked questions
Is Bolboschoenus fluviatilis native to California?
Yes. Bolboschoenus fluviatilis is native to California (recorded as native).
When does Bolboschoenus fluviatilis bloom?
Bolboschoenus fluviatilis blooms Summer.
Where in California does Bolboschoenus fluviatilis grow?
Bolboschoenus fluviatilis occurs in Sutter, Plumas, San Joaquin, Santa Cruz, Lake, Sonoma, Yolo, Alameda and other counties, at elevations of < 1300 m.
What plant family does Bolboschoenus fluviatilis belong to?
Bolboschoenus fluviatilis is in the Cyperaceae family, genus Bolboschoenus.
What habitat does Bolboschoenus fluviatilis grow in?
Bolboschoenus fluviatilis grows in Uncommon in California. Fresh water marshes.
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.