1 Spikelets solitary at each node (occasionally paired at the lowest nodes); glumes and lemmas awned or unawned; plants cespitose to strongly rhizomatous.

  2 Plants strongly rhizomatous; glume awns 0-3 mm long; lemma awns 0-5 (-10) mm long; [common and weedy introduced species]; [section Elytrigia]

  2 Plants cespitose or short-rhizomatous; glume awns 0-11 mm long; lemma awns 0-40 mm long; [rare natives and introductions]; [section Goulardia].

    3 Glumes 0.4-1.5 (-2.0) mm wide; glume margins whitish hyaline, 0.1-0.2 mm wide; [Interior Highlands of AR, MO, and OK]

    3 Glumes 1.8-2.3 mm wide; glume margins whitish hyaline or scarious, 0.2-0.3 (-0.5) mm wide; [NC, VA, WV, OH, IN, IL, and MO northwards].

      4 Lemma awns 15-40 mm long, longer than the body of the lemma

      4 Lemma awns 1-13 mm long, shorter than the body of the lemma

1 Spikelets 2-3 (-5) at each node; glumes and lemmas usually awned; plants usually cespitose, occasionally short-rhizomatous.

        5 Inflorescence rachises disarticulating at maturity; glumes 50-135 mm long (including the awns), often splitting longitudinally; leaf blades (1-) 2-4 (-6) mm wide; [rare waif in our region]

        5 Inflorescence rachises not disarticulating at maturity; glumes <43 mm long (including the awns); leaf blades 2-25 mm wide; [collectively widespread and common].

          6 Both glumes (including their awn) either 0-3 mm long and subulate or 1-25 (-27) mm long and often differing in length by > 5 mm, 0.1-0.6 mm wide, tapering from the base, with 0-1 distinct veins, persistent; rachis internodes 4-12 mm long, ca. 0.5 mm thick at the narrowest section.

             7 Spikelets appressed; lemma awns straight or curving; glumes sometimes absent, but usually 1-20 mm long, 0.1-0.6 mm wide, with a distinct vein; spikes erect or nodding

               8 Lemmas usually hairy; awns (10-) 20-30 (-35) mm long; spikelets with 3 (-5) florets; upper surface of leaf blades glabrous or short-pilose; plant somewhat glaucous

               8 Lemmas glabrous (to hispidulous near the tip); awns (8-) 10-20 (-25) mm long; spikelets with (3-) 4-5 florets; upper surface of leaf blades usually villous; plant strongly glaucous

             7 Spikelets widely spreading to horizontal; lemma awns straight (rarely slightly curving); glumes 0-3 or (13-) 15-25 (-27) mm long, with no distinct veins, < 0.2 mm wide); spikes usually erect.

                 9 Lemmas pubescent

                 9 Lemmas glabrous to scabrous.

                   10 Glumes (13-) 15-25 (-27) mm long at nearly all nodes of the inflorescence, subequal

                   10 Glumes absent or inconsistent, 0-10 (-20) mm long, unequal

          6 Both glumes (including the awns) 10-40 mm long, usually differing in length by < 5 mm, 0.2-2.3 mm wide, lanceolate to setaceous, usually widest above the base, with 2-8 veins, persistent or disarticulating; rachis internodes slender (as above) or stout (2-5 mm long and ca. 1 mm thick at the narrowest section).

                     11 Glume bases flat, thin, and evidently veined, or indurate for < 1 mm, the bodies not exceeding the adjacent (usually 8-15 mm long) lemmas; lemma awns usually curving outward; spikes usually nodding to pendent; rachis internodes (2-) 4-12 mm long.

                       12 Glumes 0.3-0.8 mm wide; lemma awns 15-25 (-35) mm long; paleas narrowly truncate; rachis internodes 5-8 (-12) mm long; blades 8-24 mm wide, dark green, usually thinly pilose above

                       12 Glumes 0.5-1.6 mm wide; lemma awns 15-40 (-50) mm long; paleas acute; rachis internodes 2-5 (-7) mm long; blades (3-) 4-15 (-20) mm wide, pale green, usually glabrous or scabridulous above

                          13 Lemmas smooth or scabridulous (rarely hirsute); spikes usually nodding (occasionally almost erect); spike internodes 3-4 mm long, not strongly glaucous.

                            14 Glumes not clearly indurate or stiffly bowed out at the base; glume awns 10-20 mm long; lemmas smooth or scabridulous; lemma awns usually 20-30 mm long, moderately outcurving; spikes 6-20 cm long

                            14 Glumes only slightly indurate and bowed out at the base; glume awns 15-25 mm long; lemmas occasionally hirsute; lemma awns usually 30-40 mm long, often strongly outcurving; spikes 15-25 (-30) cm long

                     11 Glume bases terete, indurate, and lacking evident veins for 0.5-4 mm, the bodies (unless indistinct from the awns) exceeding the adjacent (usually 6-12 mm long) lemmas; lemma awns straight; spikes erect or nodding; rachis internodes 2-5 mm long (to 7 mm in E. sp. 1).

                              15 Glumes persistent on the rachis, 0.2-1 mm wide, with 2-4 veins, the basal 0.5-2 mm essentially straight; lemmas rarely glabrous; spikelets with 1-3 (-4) florets; spikes nodding, exserted.

                                16 Blades glabrous to scabrous, pale dull green; spikes 7-25 cm long; internodes usually 3-5 mm long; spikelets with 2-3 (-4) florets; lemmas usually scabrous, 7-14 mm long, 1-5 mm longer than the acute paleas; flowering usually late Jun to late Jul

                                16 Blades villous to pilose, dark glossy green; spikes 4-12 cm long; internodes usually 2-3 mm long; spikelets with 1-2 (-3) florets; lemmas usually villous (glabrous or scabrous in the poorly known E. villosus var. arkansanus), 5.5-9 mm long, 0-1.5 mm longer than the obtuse paleas; flowering usually early Jun to August.

                                  17 Glumes scabrous; lemmas glabrous to scabrous; lemma awn 20-40 mm long; flowering Jul-Aug

                                  17 Glumes and lemmas villous; lemma awn 9-30 mm long; flowering early Jun-early Jul

                              15 Glumes disarticulating with the lowest floret, 0.7-2.3 mm wide, with (2-) 3-5 (-8) veins, the basal 1-4 mm clearly bowed-out; lemmas often glabrous; spikelets with (2-) 3-5 (-6) florets; [Elymus virginicus complex].

                                    18 Spikes (including the awns) 2.5-6 cm wide, exserted; lemma awns 15-40 mm long; blades glabrous, scabrous, or villous.

                                       19 Spikes with 9-18 nodes; internodes 4-7 mm long; blades usually lax, dark glossy green under the glaucous bloom; auricles 2-3 mm long, blackish at maturity; flowering usually in mid-May to mid-Jun.

                                         20 Glumes pubescent; lemmas pubescent

                                         20 Glumes glabrous or scabrous; lemmas glabrous or scabrous

                                       19 Spikes with 15-30 nodes; internodes 3-5 mm long; blades lax, or often ascending and involute, pale dull green; auricles 0-2 mm long, brownish at maturity; flowering usually in mid-Jun to late Jul.

                                           21 Spikelets (and usually also the foliage) pubescent; spikes usually 6-12 cm long; lemmas 6-10 mm long

                                           21 Spikelets (and usually also the foliage) glabrous to scabrous; spikes usually 9-16 cm long; lemmas 7-13 mm long

                                    18 Spikes (including the awns) 0.7-2 cm wide, exserted or sheathed; lemma awns 1-15 (-20) mm long; spikelets appressed to slightly spreading; blades usually glabrous to scabridulous.

                                             22 Lemma awns 1-3 (-5) mm long; blades often ascending, somewhat involute, those higher on the stiffly erect culms broader and more persistent; flowering usually in early Jul to mid-Aug

                                             22 Lemma awns 5-15 (-20) mm long; blades usually spreading or lax, not markedly broader or more persistent toward the culm summit; flowering usually in mid-Jun to late Jul.

                                               23 Spikes glaucous, hispidulous to villous-hirsute; spikes intermediate in exsertion; glumes indurate in the lowest 1-2 mm; ligules and auricles usually absent; flowering usually early Jul to mid-Aug

                                               23 Spikes green to glaucous, usually glabrous to scabrous; spikes on a plant either all partly included in the sheath or all fully exserted; ligules and auricles often present; flowering usually mid-Jun to mid-Jul.

                                                 24 Spikes partly sheathed; glumes 1-2.3 mm wide, strongly indurate and bowed-out in the lowest 2-4 mm; plants usually green to yellowish-brown; nodes mostly covered

                                                 24 Spikes usually exserted; glumes (0.5-) 0.7-1.5 (-1.8) mm wide, moderately indurate and bowed out in the lowest 1-2 mm; plants usually glaucous, sometimes reddish-brown at maturity; nodes often exposed.

                                                    25 Culms usually 3-8 dm tall, with 4-6 nodes; blades 2-9 mm wide, becoming involute; spikes 3.5-11 cm long, strongly glaucous; glumes usually indurate in the lowest 1-2 (or more) mm

                                                    25 Culms usually 7-10 dm tall, with 6-8 nodes; blades 3-15 mm wide, flat; spikes 4-20 cm long, pale green or glaucous; glumes indurate only in the lowest 1 mm