Calamagrostis tweedyi

Illustrator: Cindy Roché, Hana Pazdírková

Copyright: Utah State University

Plants without sterile culms; loosely cespitose, with rhizomes 1-10 cm long, 2-4 mm thick. Culms (47)60-120(150) cm, unbranched, smooth, rarely slightly scabrous; nodes 2-3. Sheaths and collars smooth; ligules (1)3.5-6(8) mm, obtuse, lacerate; blades (3)4-20(38) cm long, (2)3-8(13) mm wide, culm blades wider than 6 mm, flat, abaxial surfaces smooth, adaxial surfaces smooth or slightly scabrous, glabrous or sparsely hairy. Panicles 7-16(19) cm long, (1)1.5-2 cm wide, erect, usually contracted, sometimes interrupted near the base, pale purple to purple; branches (0.2)2.4-6.7(7.7) cm, smooth, sometimes sparsely scabrous distally, spikelet-bearing to the base. Spikelets (4.5)5.5-8(9) mm; rachilla prolongations (0.5)1-2(4) mm, hairs 1.5-3 mm. Glumes keeled, smooth or the keels scabrous, lateral veins prominent, apices acute; callus hairs 0.8-1 mm, 0.2-0.3 times as long as the lemmas, sparse; lemmas (4)4.5-6.5(7.5) mm, 0-1.5 mm shorter than the glumes, scabridulous; awns 6-8 mm, attached to the lower 1/5 – 3/10 of the lemmas, exserted more than 2 mm, stout, easily distinguished from the callus hairs, bent; anthers 2-3.5 mm. 2n = unknown.

Distribution

• Generated Map
• Legacy Map

Mont., Idaho, Wash.

Discussion

Calamagrostis tweedyi grows in montane to subalpine moist meadows and coniferous forests, often in association with Carex geyeri, at 900-2000 m. Its range extends from Washington and Oregon to western Montana.

Selected References

None.

Lower Taxa

None.