Cyperus erythrorhizos
Red rooted cyperus
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Family: Cyperaceae · Type: Grass · Native
Cyperus erythrorhizos (Red rooted cyperus) is a native California grass in the Cyperaceae family, recognized by red roots and cylindrical spikes with many spikelets diagnostic.
Red rooted cyperus is a California native annual found in the Central California Foothills and Coastal Ranges and southern desert regions in ditches, riverbanks, and shoreline habitats at elevations below 500 meters. Flowering from July to October, this plant produces small flowers in cylindric-ovoid spikes with multiple brownish spikelets 3 to 11 millimeters long. Growing with erect stems 5 to 100 centimeters tall, it develops distinctive reddish roots that give the plant its characteristic name. Its slender leaves are arranged around multiple bracts, with 3 to 11 inflorescence bracts extending 5 to 70 centimeters long. The plant produces tiny fruits approximately 0.7 to 1 millimeter long, with unequal sides and a light gray to brown glossy surface.
Identification and appearance
Key characters: 19 sympatric species; red roots and cylindrical spikes with many spikelets diagnostic
Habitat and range
Habitat: Ditches, riverbanks, shores
Elevation: < 500 m
California counties: Tehama, Glenn, Riverside, Los Angeles, Napa, San Diego, Sacramento, Butte, Colusa, Humboldt, Imperial, Kern, Lake, Marin, Merced, Orange, San Benito, San Bernardino, San Joaquin, San Luis Obispo, Santa Barbara, Siskiyou, Sonoma, Stanislaus, Ventura, Yolo, Del Norte, Mendocino, Santa Cruz, El Dorado, Madera, Kings, Tulare, Fresno, Contra Costa, Monterey, Sutter, Yuba, Tuolumne, Alameda, Calaveras, Solano, San Mateo, Santa Clara
Outside California: southern Canada, United States, northern Baja California
Bloom period
Cyperus erythrorhizos blooms Jul-Oct.
How to tell it apart
vs Carex: Cyperus has umbrella clusters with flat spikes; Carex has brown/green spikelets with seeds in individual flasks.; vs Scirpus: Cyperus has flattened ribbon-like spikes; Scirpus has rounded, cylindrical spikelets.; vs Juncus: Cyperus has triangular stems and flat flower spikes; Juncus has round stems and individual flowers.; vs Sticherus: Cyperus is a sedge with triangular stem; Sticherus is a fern with fronds.; vs Eleusine: Cyperus has triangular stems; Eleusine is a grass with round stems and obvious grass flowers.
Frequently asked questions
Is Cyperus erythrorhizos native to California?
Yes. Cyperus erythrorhizos is native to California (recorded as native).
When does Cyperus erythrorhizos bloom?
Cyperus erythrorhizos blooms Jul-Oct.
Where in California does Cyperus erythrorhizos grow?
Cyperus erythrorhizos occurs in Tehama, Glenn, Riverside, Los Angeles, Napa, San Diego, Sacramento, Butte and other counties, at elevations of < 500 m.
What plant family does Cyperus erythrorhizos belong to?
Cyperus erythrorhizos is in the Cyperaceae family, genus Cyperus.
What habitat does Cyperus erythrorhizos grow in?
Cyperus erythrorhizos grows in Ditches, riverbanks, shores.
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.