Plants perennial, with both fertile and sterile shoots; shortly
rhizomatous. Culms 20-80(100) cm, erect, glabrous or retrorsely
pubescent below the nodes. Leaves usually concentrated on the lower
1/3 of the culms; sheaths glabrous, scabridulous, or sparsely retrorse-pilose; ligules (1.2)2.5-4(6)
mm, truncate to rounded; blades to 15 cm long, 2-7 mm wide, flat,
ascending, lax, smooth, scabrous, or sparsely pilose, often involute near
the sometimes prowlike apices. Panicles (10)20-40(50) cm long, usually
1-1.5 cm wide, stiffly erect, green, tan, or purple-tinged; branches appressed-ascending,
the spikelets evenly distributed. Spikelets 4-7(8) mm, usually subsessile,
rarely on pedicels to 4 mm, ovate, with 2(3) florets; rachilla internodes 1.5-2
mm; rachilla hairs to 1 mm. Glumes subequal, usually exceeding
the lowest florets; lower glumes 4-7 mm; upper glumes 4-6.5
mm long, a little wider than the lower glumes; callus hairs less
than 0.5 mm; lemmas 4-6.5 mm, lanceolate, firmer than the glumes,
scabridulous-puberulent, obscurely bifid, awns absent or to 2 mm, arising
just below and rarely exceeding the apices; paleas shorter than
the lemmas; anthers (0.6)1(1.5) mm. Caryopses to 3 mm, pubescent.
2n = 14.
Trisetum wolfii grows in moist meadows, marshes, and stream banks in aspen groves and parks in the spruce-fir forest zone, at medium to high, but usually not alpine, elevations.It is native to southwestern Canada and the western United States.