Cyperus iria
Ricefield flatsedge
(c) Douglas Goldman, some rights reserved (CC BY-SA), uploaded by Douglas Goldman · licence
Family: Cyperaceae · Type: Grass · Not Native
Cyperus iria (Ricefield flatsedge) is a non-native California grass in the Cyperaceae family, recognized by notched bracts with small points and 2 lateral veins diagnostic.
Ricefield flatsedge is a naturalized annual sedge found in the Yuba County region of the Sacramento Valley in ditches and pond shores at elevations below 100 meters. Flowering from August to October, this plant produces golden brown to brown flowers in flattened spikelets 4 to 20 millimeters long, arranged in 4 to 8 rays. Growing 20 to 30 centimeters tall with 3 to 10 three-sided stems, it forms a delicate and spreading inflorescence. Its flower bracts are small, about 1.3 to 1.8 millimeters long, with obovate to round shapes that have a tiny point and two distinct lateral veins. The fruit is a glossy, fine-pitted obovoid structure approximately 1.2 to 1.4 millimeters long.
Identification and appearance
Key characters: 13 sympatric species; notched bracts with small points and 2 lateral veins diagnostic
Habitat and range
Habitat: Ditches, pond shores
Elevation: < 100 m
California counties: Butte, Yuba
Outside California: eastern United States, Mexico, Central America, South America, Old World
Bloom period
Cyperus iria blooms Aug-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 iria native to California?
No. Cyperus iria is not native to California (recorded as not native).
When does Cyperus iria bloom?
Cyperus iria blooms Aug-Oct.
Where in California does Cyperus iria grow?
Cyperus iria occurs in Butte, Yuba, at elevations of < 100 m.
What plant family does Cyperus iria belong to?
Cyperus iria is in the Cyperaceae family, genus Cyperus.
What habitat does Cyperus iria grow in?
Cyperus iria grows in Ditches, pond 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.