Page authors: Don Knoke, David Giblin
Bromus japonicus
Japanese brome

Distribution: Occurring east of the Cascades crest in Washington; southern British Columbia to California, east across North America to the Atlantic Coast.

Habitat: Sagebrush desert and grasslands to lower mountain forests; often a weed of roadsides and waste land.

Flowers: June-August

Origin: Introduced from Eurasia

Growth Duration: Annual

Conservation Status: Not of concern

Pollination: Wind


Annual, the culms 2-5 dm. tall.


Sheaths closed, densely long-hairy; ligules 0.5-1.5 mm. long, hairy; blades flat, 1.5-3 mm. broad.


Inflorescence an open, pyramidal panicle 7-15 cm. long, spreading or drooping, the pedicles longer than the spikelets; spikelets 7- to 12-flowered, 20-25 mm. long, glabrous; first glume lanceolate, 3-nerved, 4-6 mm. long, the second 5-nerved, somewhat longer and broader; lemmas broadly oblong-lanceolate, curved around the fruit, 8-10 mm. long, the tip obtuse, but splitting to the awn, which is attached 1-2.5 mm. below the tip; awn 8-12 mm. long, twisted and bent; paleas 1.5-3 mm. shorter than the lemmas; anthers not exerted.

Accepted Name:
Bromus japonicus Thunb. ex Murray
Publication: Fl. Jap. 52, pl. 11. 1784. 1784.

Synonyms & Misapplications:
Bromus japonicus Thunb. ex Murray var. porrectus Hack.
Bromus patulus Mert. & W.D.J. Koch
Additional Resources:

PNW Herbaria: Specimen records of Bromus japonicus in the Consortium of Pacific Northwest Herbaria database

WA Flora Checklist: Bromus japonicus checklist entry

OregonFlora: Bromus japonicus information

E-Flora BC: Bromus japonicus atlas page

CalPhotos: Bromus japonicus photos

26 photographs:
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