Poa trivialis subsp. trivialis
Rough blue grass
Photo: parent species Poa trivialis · no rights reserved · CC0
Family: Poaceae · Type: Perennial
Poa trivialis subsp. trivialis (Rough blue grass) is a California perennial in the Poaceae family, recognized by scabrous sheaths, smaller anthers, and glabrous lemma margins.
Rough blue grass is a naturalized perennial found in disturbed moist places at elevations below 700 meters. Flowering from April to July, this grass produces small green-tinted spikelets with delicate flower clusters. Growing in dense clumps or with short spreading stolons, it forms low-growing clusters 30 to 50 centimeters tall. Its leaf sheaths are rough-textured with prominent ligules 3 to 7 millimeters long, and individual leaves have a scabrous (slightly scratchy) surface. The small lemmas are 2 to 3 millimeters long with glabrous marginal veins.
Identification and appearance
Key characters: 24 sympatric species; distinguished by scabrous sheaths, smaller anthers, and glabrous lemma margins
Habitat and range
Habitat: Disturbed moist places
Elevation: < 700 m
Outside California: to Alaska, eastern North America, native to Europe
Bloom period
Poa trivialis subsp. 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
When does Poa trivialis subsp. trivialis bloom?
Poa trivialis subsp. trivialis blooms Apr-Jul.
What plant family does Poa trivialis subsp. trivialis belong to?
Poa trivialis subsp. trivialis is in the Poaceae family, genus Poa.
What habitat does Poa trivialis subsp. trivialis grow in?
Poa trivialis subsp. trivialis grows in Disturbed moist places.
Related species
Other California species in the same genus, family, or bioregion.
- Poa unilateralis subsp. unilateralis — San francisco blue grass
- Poa wheeleri — Hooker's bluegrass
- Poa abbreviata — Dwarf blue grass
- Poa abbreviata subsp. marshii — Marsh's blue grass
- Poa abbreviata subsp. pattersonii — Patterson's blue grass
- Poa annua — Annual blue grass
- Polypogon australis — Chilean beard grass
- Polypogon imberbis — Streambank rabbits foot grass
Sources: Jepson eFlora · CalPhotos
Last updated 2026-09-30
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.