Page author: Don Knoke
Poa annua
annual blue grass

Distribution: Common weed throughout the Pacific Northwest.

Habitat: Lawns, gardens, roadsides, and waste ground to open woods.

Flowers: March - August

Origin: Introduced

Growth Duration: Annual, Biennial

Conservation Status: Not of concern

Pollination: Wind


Glabrous annual, the culms 5-20 cm. tall, hollow, rooting at the nodes and forming mats.


Sheaths closed below, but open over half their length; ligules about 1 mm. long, rounded to truncate; blades 1-3.5 mm. broad, usually folded, the tip prow-like.


Inflorescence a pyramidal panicle 3-8 cm. long, the branches spreading and somewhat rigid; spikelets 3- to 6-flowered, 4-6 mm. long; glumes unequal, the first 1-nerved, about 2 mm. long, the second 3-nerved, much the broader; florets rather distant, the rachilla visible; lemmas about 3.5 mm. long, 5-nerved, the margins purplish and papery, usually pubescent along the keel and marginal nerves; paleas slightly shorter than the lemmas, 2-keeled.

Accepted Name:
Poa annua L.
Publication: Sp. Pl. 1: 68. 1753.

Synonyms & Misapplications:
Poa annua L. var. aquatica Asch.
Poa annua L. var. reptans Hausskn.
Additional Resources:

PNW Herbaria: Specimen records of Poa annua in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Poa annua checklist entry.

OregonFlora: Poa annua information.

E-Flora BC: Poa annua atlas page.

CalPhotos: Poa annua photos.

USDA Plants: Poa annua information.

19 photographs:
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