Bromus arizonicus
Arizona brome
Family: Poaceae · Type: Grass · Native
Bromus arizonicus (Arizona brome) is a native California grass in the Poaceae family, recognized by strongly keeled lemmas and minute anthers diagnostic.
Arizona brome is a California native annual grass found in southern North Coast Ranges, Great Valley, San Francisco Bay Area, southern Coast Ranges, southern California Coast, Channel Islands, and desert regions in open, disturbed places and fields at elevations below 2,200 meters. Flowering from March to June, this grass produces pale green to straw-colored spikelets 18 to 25 millimeters long with delicate branching inflorescences. Growing 40 to 90 centimeters tall with ascending to erect stems, it develops spreading lower branches in its grass clusters. Its leaves are glabrous or slightly hairy, with narrow blades 1.5 to 10 millimeters wide and short ligules 1 to 2 millimeters long. The grass produces lemmas with distinctive 7 to 15 millimeter awns, typically with hairy margins and backs.
Identification and appearance
Key characters: 31 sympatric species; strongly keeled lemmas and minute anthers diagnostic
Habitat and range
Habitat: Open, disturbed places, fields
Elevation: < 2200 m
California counties: San Bernardino, Kern, Los Angeles, Monterey, Orange, Riverside, San Diego, San Joaquin, Santa Barbara, Yolo, Fresno, San Francisco, Ventura, Merced, Yuba, Tuolumne, Tulare, Kings, San Luis Obispo, Sonoma, Mendocino, Stanislaus, El Dorado, Alameda, Napa
Outside California: Arizona, northwestern Mexico
Bloom period
Bromus arizonicus blooms Mar-Jun.
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 arizonicus native to California?
Yes. Bromus arizonicus is native to California (recorded as native).
When does Bromus arizonicus bloom?
Bromus arizonicus blooms Mar-Jun.
Where in California does Bromus arizonicus grow?
Bromus arizonicus occurs in San Bernardino, Kern, Los Angeles, Monterey, Orange, Riverside, San Diego, San Joaquin and other counties, at elevations of < 2200 m.
What plant family does Bromus arizonicus belong to?
Bromus arizonicus is in the Poaceae family, genus Bromus.
What habitat does Bromus arizonicus grow in?
Bromus arizonicus grows in Open, disturbed places, fields.
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.