Poa annua
Annual blue grass
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Family: Poaceae · Type: Grass · Not Native
Poa annua (Annual blue grass) is a non-native California grass in the Poaceae family, recognized by distinctive triangular inflorescence shape and annual habit.
Annual blue grass is a naturalized annual grass found especially near the California coast in disturbed moist ground at elevations generally below 2,000 meters. Flowering from February to September, this grass produces pale green to yellow-green spikelets in open, triangular inflorescences up to 10 centimeters long. Growing in dense tufts or with spreading stolons, it reaches heights of 2 to 20 centimeters with soft, flat leaf blades 1 to 3 millimeters wide. Its leaves have open sheaths and short ligules 1 to 5 millimeters long, with bright to yellow-green coloration. The small spikelets feature lemmas 2.5 to 4 millimeters long with soft hairy veins, typical of this widespread introduced grass.
Identification and appearance
Key characters: 47 sympatric species; distinctive triangular inflorescence shape and annual habit
Habitat and range
Habitat: Abundant. Disturbed moist ground
Elevation: generally < 2000 m
California counties: Los Angeles, Sierra, San Luis Obispo, San Bernardino, Riverside, Colusa, Calaveras, Santa Cruz, Fresno, Kern, Alameda, Lake, San Joaquin, Yolo, Santa Barbara, Siskiyou, San Diego, San Francisco, Mendocino, Tulare, Orange, Monterey, Santa Clara, Butte, Stanislaus, Inyo, Humboldt, Marin, Plumas, San Mateo, Shasta, Sonoma, Tuolumne, Ventura, Sutter, Imperial, Merced, El Dorado, Kings, Sacramento, Placer, Nevada, Amador, Glenn, Mariposa, Contra Costa, Madera, Mono, Napa, San Benito, Trinity, Yuba, Del Norte, Tehama, Solano, Modoc
Outside California: widespread temperate North America, +- worldwide, native to Eurasia
Bloom period
Poa annua blooms Feb-Sep.
How to tell it apart
vs Festuca: Poa has boat-shaped, keeled leaf tips; Festuca leaves are flat or rolled but never keeled like a ship's prow.; vs Melica: Poa has fine, narrow leaves with boat-shaped tips; Melica has wider, flat leaves without the distinctive keel.; vs Nassella: Poa leaves have boat-shaped tips you can feel; Nassella leaves roll inward and lack the keel.; vs Koeleria: Poa has cobwebby hairs at seed base and keeled leaf tips; Koeleria lacks both features.; vs Holcus: Poa has boat-shaped leaf tips; Holcus leaves are flat and soft-hairy without any keel.
Frequently asked questions
Is Poa annua native to California?
No. Poa annua is not native to California (recorded as not native).
When does Poa annua bloom?
Poa annua blooms Feb-Sep.
Where in California does Poa annua grow?
Poa annua occurs in Los Angeles, Sierra, San Luis Obispo, San Bernardino, Riverside, Colusa, Calaveras, Santa Cruz and other counties, at elevations of generally < 2000 m.
What plant family does Poa annua belong to?
Poa annua is in the Poaceae family, genus Poa.
What habitat does Poa annua grow in?
Poa annua grows in Abundant. Disturbed moist ground.
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.