Page authors: Don Knoke, David Giblin
Calamagrostis tweedyi
Cascade reedgrass

Distribution: Occurring chiefly east of the Cascades crest in central Washington; central Washington to southern Oregon, east to Idaho and Montana.

Habitat: Moist meadows and subalpine slopes, usually in forest edge or understory.

Flowers: June-August

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern


Perennial with short, stout rhizomes, the culms 6-15 dm. tall, glabrous.


Sheaths open; ligules 6-15 mm. long, irregularly jagged; blades of the culm leaves flat, up to 12 cm. long; blades of the sterile shoots nearly twice as long and half as wide.


Inflorescence a compact panicle 8-16 cm. long, often interrupted below; spikelets 1-flowered; glumes 5.5-7 mm. long; lemma slightly shorter than the glumes, with an awn attached about mid-length, the awn twisted and bent, exceeding the glumes by about 5 mm.; palea subequal to the lemma, the rachilla prolonged behind the palea 2-4 mm., strongly bearded; callus very lightly bearded.

Accepted Name:
Calamagrostis tweedyi (Scribn.) Scribn.
Publication: Contributions from the United States National Herbarium 3(1): 83. 1892.

Synonyms & Misapplications:
(none provided)
Additional Resources:

PNW Herbaria: Specimen records of Calamagrostis tweedyi in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Calamagrostis tweedyi checklist entry.

OregonFlora: Calamagrostis tweedyi information.

E-Flora BC: Calamagrostis tweedyi atlas page.

CalPhotos: Calamagrostis tweedyi photos.

USDA Plants: Calamagrostis tweedyi information.

2 photographs:
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