Bromus diandrus
Ripgut grass, Ripgut Grass
Photo by Chez Brungraber
Family: Poaceae · Type: Grass · Not Native
Conservation status: Cal-IPC Yes
Bromus diandrus (Ripgut grass) is a non-native California grass in the Poaceae family, recognized by extremely long awns and large spikelets diagnostic.
Ripgut grass is a naturalized annual grass found in California in open, generally disturbed areas at elevations below 2,170 meters. Flowering from February to July, this grass produces pale straw-colored flowers in loose, spreading clusters 15 to 25 centimeters long with distinctively nodding lower branches. Growing 15 to 120 centimeters tall with erect to spreading stems, it develops an open, branching structure with prominent seed heads. Its leaf blades are 2 to 7 millimeters wide, covered in soft hairs, with a small ligule 1 to 3 millimeters long. The seeds have characteristic long awns 30 to 65 millimeters in length, which give the plant its common name "ripgut" due to their ability to easily penetrate animal fur and skin.
Identification and appearance
Key characters: 34 sympatric species; extremely long awns and large spikelets diagnostic
Habitat and range
Habitat: Open, generally disturbed areas
Elevation: < 2170 m
California counties: Humboldt, Los Angeles, Orange, Calaveras, Sutter, Riverside, San Luis Obispo, Fresno, Kern, San Diego, Tulare, San Bernardino, Alameda, Amador, Butte, El Dorado, Imperial, Inyo, Lake, Marin, Monterey, Placer, Sacramento, San Francisco, San Mateo, Santa Barbara, Santa Cruz, Santa Clara, Sonoma, Trinity, Tuolumne, Ventura, Yolo, Colusa, Contra Costa, Madera, Mendocino, Merced, Plumas, Shasta, Siskiyou, Stanislaus, Glenn, Yuba, Solano, Nevada, San Joaquin, Tehama, San Benito, Napa, Kings, Mariposa, Modoc, Del Norte, Lassen
Outside California: to British Columbia, Colorado, Texas, Mexico, Guatemala, South America, native to Europe
Bloom period
Bromus diandrus blooms Feb-Jul.
Conservation status
Cal-IPC Yes
How to tell it apart
vs Nassella: Bromus has closed leaf sheaths and large spikelets; Nassella has open sheaths and needle-like awns.; vs Hordeum: Bromus has separate large spikelets; Hordeum has three spikelets grouped at each node.; vs Avena: Bromus lemmas have two teeth at tip; Avena lemmas have a twisted awn from the back.; vs Lolium: Bromus spikelets are stalked in clusters; Lolium spikelets sit edgewise against the stem.; vs Festuca: Bromus leaf sheaths are closed; Festuca sheaths split open halfway down.
Frequently asked questions
Is Bromus diandrus native to California?
No. Bromus diandrus is not native to California (recorded as not native).
When does Bromus diandrus bloom?
Bromus diandrus blooms Feb-Jul.
Where in California does Bromus diandrus grow?
Bromus diandrus occurs in Humboldt, Los Angeles, Orange, Calaveras, Sutter, Riverside, San Luis Obispo, Fresno and other counties, at elevations of < 2170 m.
What plant family does Bromus diandrus belong to?
Bromus diandrus is in the Poaceae family, genus Bromus.
Is Bromus diandrus invasive in California?
Bromus diandrus is listed by Cal-IPC with an invasiveness rating of Yes.
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.