Poa unilateralis subsp. unilateralis
San francisco blue grass, San Francisco Blue Grass
(c) Trevor Van Loon, some rights reserved (CC BY) · licence
Family: Poaceae · Type: Grass · Native
Poa unilateralis subsp. unilateralis (San francisco blue grass) is a native California grass in the Poaceae family, recognized by coastal saline habitat and compact inflorescence.
San francisco blue grass is a California native perennial found in northern Coast and central Coast bioregions on islands and coastal bluffs in saline, heavy soils at elevations below 410 meters. Flowering from March to June, this plant produces small, subtle flowers in dense, cylindric clusters. Growing in tufted clumps 20 to 40 centimeters tall with soft, slender stems, it forms compact and densely clustered grass mats. Its leaf blades are narrow, soft, and generally 1 to 5 millimeters wide, emerging from open leaf sheaths with smooth ligules 1.5 to 5 millimeters long. The plant's delicate spikelets have glabrous or slightly hairy lemmas and produce small anthers 1.5 to 3 millimeters in length.
Identification and appearance
Key characters: 24 sympatric species; distinguished by coastal saline habitat and compact inflorescence
Habitat and range
Habitat: Islands, coastal bluffs, in +- saline, heavy soils
Elevation: < 410 m
California counties: San Mateo, Marin, Monterey, Mendocino
Outside California: to northern Oregon
Bloom period
Poa unilateralis subsp. unilateralis blooms Mar-Jun.
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 unilateralis subsp. unilateralis native to California?
Yes. Poa unilateralis subsp. unilateralis is native to California (recorded as native).
When does Poa unilateralis subsp. unilateralis bloom?
Poa unilateralis subsp. unilateralis blooms Mar-Jun.
Where in California does Poa unilateralis subsp. unilateralis grow?
Poa unilateralis subsp. unilateralis occurs in San Mateo, Marin, Monterey, Mendocino, at elevations of < 410 m.
What plant family does Poa unilateralis subsp. unilateralis belong to?
Poa unilateralis subsp. unilateralis is in the Poaceae family, genus Poa.
What habitat does Poa unilateralis subsp. unilateralis grow in?
Poa unilateralis subsp. unilateralis grows in Islands, coastal bluffs, in +- saline, heavy soils.
Related species
Other California species in the same genus, family, or bioregion.
- 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
- Poa atropurpurea — San bernardino bluegrass
- Polypogon australis — Chilean beard grass
- Polypogon imberbis — Streambank rabbits foot grass
- Polypogon interruptus — Ditch beard grass
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.