Cyperus flavescens
Yellow flatsedge
(c) Zihao Wang, some rights reserved (CC BY) · licence
Family: Cyperaceae · Type: Grass · Not Native
Cyperus flavescens (Yellow flatsedge) is a non-native California grass in the Cyperaceae family, recognized by yellow bracts without lateral veins and wrinkled black fruits diagnostic.
Yellow flatsedge is a naturalized annual found in central Sierra Nevada foothills and Sacramento Valley in marshy, damp places at elevations of 500 to 1,000 meters. Flowering from June to October, this plant produces small yellow-tinged flowers in open, ovoid spikes 8 to 25 millimeters wide. Growing with slender stems 5 to 30 centimeters tall, featuring 2 to 3 spreading bracts 1 to 12 centimeters long. Its spikelets are lance-oblong, flat, and 5 to 15 millimeters long with ovate flower bracts. The fruit is a small black, two-sided obovoid structure 1 to 1.2 millimeters long with a distinctive network of rectangular epidermal cells.
Identification and appearance
Key characters: 14 sympatric species; yellow bracts without lateral veins and wrinkled black fruits diagnostic
Habitat and range
Habitat: Marshy, damp places
Elevation: 500-1000 m
California counties: Butte, Nevada, Yuba, Tehama
Outside California: to southern Canada, South America, Old World
Bloom period
Cyperus flavescens blooms Jun-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 flavescens native to California?
No. Cyperus flavescens is not native to California (recorded as not native).
When does Cyperus flavescens bloom?
Cyperus flavescens blooms Jun-Oct.
Where in California does Cyperus flavescens grow?
Cyperus flavescens occurs in Butte, Nevada, Yuba, Tehama, at elevations of 500-1000 m.
What plant family does Cyperus flavescens belong to?
Cyperus flavescens is in the Cyperaceae family, genus Cyperus.
What habitat does Cyperus flavescens grow in?
Cyperus flavescens grows in Marshy, damp places.
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.