Isolepis carinata
Keeled bulrush
(c) Sam Kieschnick, some rights reserved (CC BY) · licence
Family: Cyperaceae · Type: Grass · Native
Isolepis carinata (Keeled bulrush) is a native California grass in the Cyperaceae family, recognized by annual habit and 3-sided fruit with concave sides that is as deep as wide.
Keeled bulrush is a California native annual found in northern coastal, central coastal, and San Francisco Bay Area bioregions in grasslands, rock barrens, and open woodland at elevations below 800 meters. Flowering in spring, this plant produces small, delicate flowers in compact clusters with subtle brownish-green tones. Growing with slender stems 1 to 25 centimeters tall, it forms a single thin leaf and delicate inflorescence. Its single leaf and flower bracts are distinctive, with bracts often clasping and shedding fruit that is tiny and precisely 1 to 1.5 millimeters wide. The fruit is three-sided with slightly concave sides, creating a unique geometric profile in its miniature grassland habitats.
Identification and appearance
Key characters: 3 sympatric species; key features are annual habit and 3-sided fruit with concave sides that is as deep as wide
Habitat and range
Habitat: Often drying wet places in grassland, rock barrens, open woodland
Elevation: < 800 m
California counties: Orange, Marin, Monterey, San Luis Obispo, Sonoma, San Diego, Ventura, Mendocino, Butte, Santa Cruz, San Mateo, Humboldt, Napa
Outside California: southeastern United States
Bloom period
Isolepis carinata blooms Spring.
How to tell it apart
vs Eleocharis: Isolepis has multiple parallel veins in its bracts; Eleocharis bracts have just a single midvein.; vs Juncus: Isolepis flowers grow in spikelets with overlapping scales; Juncus has separate flowers with 6 perianth parts.; vs Carex: Isolepis has bisexual flowers in open spikelets; Carex has separate male/female flowers in enclosed sacs.; vs Triglochin: Isolepis has scaly spikelets typical of sedges; Triglochin has spike-like flower clusters with capsules.; vs Lipocarpha: Isolepis has one bract per flower; Lipocarpha has two nested bracts (inner and outer) per flower.
Frequently asked questions
Is Isolepis carinata native to California?
Yes. Isolepis carinata is native to California (recorded as native).
When does Isolepis carinata bloom?
Isolepis carinata blooms Spring.
Where in California does Isolepis carinata grow?
Isolepis carinata occurs in Orange, Marin, Monterey, San Luis Obispo, Sonoma, San Diego, Ventura, Mendocino and other counties, at elevations of < 800 m.
What plant family does Isolepis carinata belong to?
Isolepis carinata is in the Cyperaceae family, genus Isolepis.
What habitat does Isolepis carinata grow in?
Isolepis carinata grows in Often drying wet places in grassland, rock barrens, open woodland.
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.