Bolboschoenus robustus
Seacoast bulrush, Seacoast Bulrush
Photo by Chez Brungraber
Family: Cyperaceae · Type: Grass · Native
Bolboschoenus robustus (Seacoast bulrush) is a native California grass in the Cyperaceae family, recognized by coastal restriction, orange anthers, floating fruits, and mostly unbranched inflorescence.
Seacoast bulrush is a California native perennial found in Suisun Marsh, central coast, San Francisco Bay, and southern coastal regions in brackish to saline coastal marshes at sea level. Flowering during summer, this plant produces spikelets with small flowers, typically 10 to 30 millimeters long and 6 to 10 millimeters wide. Growing with robust stems 50 to 150 centimeters tall and 4 to 8 millimeters in diameter, it forms dense clusters in marsh environments. Its leaves have papery, veiny sheaths with blades 4 to 12 millimeters wide, and distinctive orange anthers with three stigmas. The fruit is approximately 3 millimeters long, slightly flattened, and uniquely adapted to float on water surfaces.
Identification and appearance
Key characters: 3 sympatric species; key features are coastal restriction, orange anthers, floating fruits, and mostly unbranched inflorescence
Habitat and range
Habitat: Local in California. Brackish to saline coastal marshes
Elevation: +- 0 m.
California counties: Orange, Riverside, Sonoma, Napa, Contra Costa, Marin, Solano, San Luis Obispo, Yuba, San Francisco, Humboldt, Mendocino, Ventura, Los Angeles, Santa Barbara, Monterey, Glenn, Kern, Inyo, Alameda, Yolo, San Mateo, Santa Cruz
Outside California: Maine to Florida, Mexico, South America
Bloom period
Bolboschoenus robustus 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 robustus native to California?
Yes. Bolboschoenus robustus is native to California (recorded as native).
When does Bolboschoenus robustus bloom?
Bolboschoenus robustus blooms Summer.
Where in California does Bolboschoenus robustus grow?
Bolboschoenus robustus occurs in Orange, Riverside, Sonoma, Napa, Contra Costa, Marin, Solano, San Luis Obispo and other counties, at elevations of +- 0 m..
What plant family does Bolboschoenus robustus belong to?
Bolboschoenus robustus is in the Cyperaceae family, genus Bolboschoenus.
What habitat does Bolboschoenus robustus grow in?
Bolboschoenus robustus grows in Local in California. Brackish to saline coastal 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.