Poa trivialis
Rough blue grass
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Family: Poaceae · Type: Grass · Not Native
Poa trivialis (Rough blue grass) is a non-native California grass in the Poaceae family, recognized by scabrous sheaths and sickle-shaped glumes.
Rough blue grass is a naturalized perennial grass found in northern coastal California regions in disturbed moist places at elevations below 700 meters. Flowering from April to July, this grass produces pale green to green-white flowers in open, lanceolate to ovate inflorescences 8 to 25 centimeters long. Growing with dense basal tufts 30 to 100 centimeters tall, it develops short stolons and forms cespitose clumps. Its leaf blades are soft, flat, and 1 to 5 millimeters wide, with open sheaths that are slightly rough to the touch and ligules 3 to 7 millimeters long. The plant's spikelets have distinctive sickle-shaped lower glumes and lemmas with hairy keels and marginal veins.
Identification and appearance
Key characters: 24 sympatric species; distinguished by scabrous sheaths and sickle-shaped glumes
Habitat and range
Habitat: Disturbed moist places
Elevation: < 700 m.
Outside California: to Alaska, eastern North America; native to Europe.
Bloom period
Poa trivialis blooms Apr-Jul.
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 trivialis native to California?
No. Poa trivialis is not native to California (recorded as not native).
When does Poa trivialis bloom?
Poa trivialis blooms Apr-Jul.
What plant family does Poa trivialis belong to?
Poa trivialis is in the Poaceae family, genus Poa.
What habitat does Poa trivialis grow in?
Poa trivialis grows in Disturbed moist places.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · 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.