Calamagrostis canadensis var. canadensis
Culms (50) 65-80 (160) cm, often branching above the base, smooth or slightly scabrous beneath the panicles; nodes (2) 3-4 (6). Sheaths smooth or scabrous; collars usually scabrous, rarely smooth or hairy; ligules (1) 4-6 (12) mm; blades (11) 16-31 (41) cm long, (2) 2.5-5 (8) mm wide, adaxial surfaces usually strongly scabrous, rarely smooth, often glaucous. Panicles (9) 11-14 (19) cm long, (1) 2-3 (7) cm wide, often contracted when young, usually purplish, sometimes greenish to straw-colored; branches 2.9-4.5 (5.7) cm. Spikelets 2.5-3.5 (4) mm; rachilla prolongations 0.5-1 mm, hairs 2.5-3.2 mm. Glumes rounded to broadly keeled, smooth or scabrous, often only the keels scabrous, prickles straight, midveins raised, lateral-veins obscure to prominent, apices usually acute, rarely acuminate; callus hairs (1.7) 2.5-2.9 (3.1) mm, (0.7) 0.9-1.1 (1.4) times as long as the lemmas; lemmas (2.2) 2.5-3.1 (4) mm, 0-1.6 mm shorter than the glumes; awns 0.9-2.6 mm, attached to the lower (1/10) 1/5 – 2/5 (7/10) of the lemmas, usually not exserted, usually straight; anthers (0.8) 1.2-1.3 (2) mm. 2n = 42-66.
Wash., Del., Wis., W.Va., Wyo., N.H., N.J., N.Mex., N.C., Nebr., Tenn., N.Y., Pa., Alaska, Nev., Va., Colo., Alta., B.C., Man., N.B., Nfld. and Labr., N.S., N.W.T., Ont., P.E.I., Que., Sask., Yukon, Vt., Ill., Ga., Ind., Iowa, Ariz., Calif., Idaho, Conn., Maine, Mass., Kans., Md., Mich., N.Dak., Ohio, Utah, Mo., Minn., R.I., Mont., Oreg., S.Dak.
Calamagrostis canadensis var. canadensis is wide-spread throughout the range of the species, except on the arctic islands, Greenland, and the adjacent mainland.
"decumbent" is not a number.