1. Spikelets 1 at all or most nodes; glumes with flat, non-indurate bases, glume bodies linear-lanceolate to obovate, margins hyaline, scarious, or chartaceous; lemmas awned or unawned [for opposite lead, see p. 292]. | → 2 |
2. Anthers 3-7 mm long; plants often strongly rhizomatous, sometimes not or only weakly rhizomatous. | → 3 |
3. At least some lemmas with strongly divergent, outcurving, or recurved awns. | → 4 |
4. Culms prostrate to decumbent and geniculate, 20-50 cm tall; plants of subalpine and alpine habitats | E. sierrae |
4. Culms erect or decumbent only at the base, (15)40-130 cm tall; plants of valley and montane, but not subalpine or alpine, habitats. | → 5 |
5. Plants strongly rhizomatous; blades 1-3 mm wide | E. albicans |
5. Plants cespitose or weakly rhizomatous; blades 1.5-6 mm wide. | → 6 |
6. Spikes often drooping to pendent at maturity; rachis internodes 11-17 mm long; plants of the southwestern United States | E. arizonicus |
6. Spikes erect to slightly nodding at maturity; rachis internodes 5-12 mm long; plants of the northwestern contiguous United States | E. wawawaiensis |
3. Lemmas unawned or with straight to flexuous awns. | → 7 |
7. Lemmas 12-14 mm long; plants not or weakly rhizomatous. | → 8 |
8. Palea keels straight or slightly outwardly curved below the apices, apices about 0.2 mm wide between the vein ends | E. glaucus |
8. Palea keels distinctly outwardly curved below the apices; apices 0.3-0.7 mm wide between the vein ends | E. semicostatus |
7. Lemmas 7-12 mm long; plants not, weakly, or strongly rhizomatous. | → 9 |
9. Glumes keeled distally, keels smooth and inconspicuous proximally, scabrous and conspicuous distally; lemmas glabrous. | → 10 |
10. Adaxial surfaces of the blades usually sparsely pilose, sometimes glabrous, veins smooth, the primary veins separated by secondary veins; plants strongly rhizomatous | E. repens |
10. Adaxial surfaces of the blades glabrous, veins smooth or scabrous, all veins more or less equally prominent; plants slightly to moderately rhizomatous | E. hoffmannii |
9. Glumes not keeled or keeled throughout their length, keels smooth or scabrous throughout, sometimes hairy, conspicuous or not; lemmas glabrous or hairy. | → 11 |
11. Plants strongly rhizomatous; glumes 5-9 mm long; lemmas densely to sparsely hairy or glabrous | E. lanceolatus |
11. Plants cespitose or weakly rhizomatous; glumes 6-19 mm long; lemmas glabrous or pubescent, never densely hairy. | → 12 |
12. Spikelets usually at least twice as long as the internodes; internodes 4-12 mm long; glumes often awned, sometimes unawned; blades usually lax | E. glaucus |
12. Spikelets from shorter than to almost twice as long as the internodes; internodes 9-27 mm long; glumes unawned; blades usually straight | E. stebbinsii |
2. Anthers 0.7-3 mm long; plants usually not or weakly rhizomatous, sometimes strongly rhizomatous. | → 13 |
13. Culms prostrate or strongly decumbent at the base; disarticulation in the rachises or beneath the florets; plants of subalpine, alpine, and arctic habitats. | → 14 |
14. Glumes unawned or with awns to 1 mm long; plants of arctic habitats | E. alaskanus |
14. Glumes awned, awns 3-30 mm long; plants of subalpine and alpine habitats. | → 15 |
15. Anthers 1-1.6 mm long; internodes 2.5-5(7) mm long; disarticulation initially in the rachises; spikelets appressed to ascending | E. scribneri |
15. Anthers 2-3.5 mm long; internodes 5-15 mm long; rachises not disarticulating; spikelets ascending to divergent | E. sierrae |
13. Culms usually ascending to erect, sometimes geniculate or weakly decumbent at the base; disarticulation beneath the florets; plants of sea level to subalpine habitats. | → 16 |
16. Lemmas with coarse, stiff, marginal hairs up to 1 mm long; paleas 2/3 – 4/5 as long as the lemmas, with wide, rounded apices | E. ciliaris |
16. Lemmas with the marginal hairs, if present, similar to those elsewhere on the lemma; paleas 3/4 as long as to slightly longer than the lemmas, tapering to the apices. | → 17 |
17. Lemmas awned, awns 7-40 mm long. | → 18 |
18. Lemma awns strongly arcuate to outcurving or recurved. | → 19 |
19. Spikes 8-12 cm long, straight, erect or inclined; blades 2-4 mm wide | E. bakeri |
19. Spikes 7-30 cm long, flexuous, nodding to pendent; blades 5-14 mm wide | E. sibiricus |
18. Lemma awns usually straight or flexuous, or, if shorter than 10 mm, sometimes weakly curving. | → 20 |
20. Glumes with hairs on the adaxial (inner) surface, these often inconspicuous | E. caninus |
20. Glumes glabrous on the adaxial (inner) surface. | → 21 |
21. Palea keels distinctly outwardly curved below the apices, winged, not or scarcely extending beyond the intercostal region; apices 0.3-0.5 mm wide | E. tsukushiensis |
21. Palea keels straight or slightly outwardly curved below the apices, not winged, often extending beyond the intercostal region, sometimes forming teeth; apices 0.1-0.3 mm wide. | → 22 |
22. Glumes 1.8-2.3 mm wide, margins 0.2-0.3 mm wide | E. trachycaulus |
22. Glumes 0.4-1.5(2) mm wide, margins 0.1-0.2 mm wide. | → 23 |
23. Spikes erect or almost so, 0.5-2 cm wide | E. glaucus |
23. Spikes nodding to pendent, 2-5 cm wide | E. sibiricus |
17. Lemmas unawned or with awns up to 7 mm long. | → 24 |
24. Plants strongly rhizomatous | E. lanceolatus |
24. Plants not or only shortly rhizomatous. | → 25 |
25. Glumes 1/3 – 2/3 as long as the adjacent lemmas. | → 26 |
26. Glumes 0.8-1.8 mm wide, lanceolate, margins subequal; lemmas evenly hairy or glabrous distally | E. macrourus |
26. Glumes 1.5-2 mm wide, oblanceolate to obovate, margins unequal; lemmas glabrous, evenly hairy, or more densely hairy distally | E. alaskanus |
25. Glumes 3/4 as long as to slightly longer than the adjacent lemmas. | → 27 |
27. Glumes 3(5)-veined; glume margins unequal, the wider margins 0.3-1 mm wide, usually widest in the distal 1/3; lemma awns 0.5-3 mm long | E. violaceus |
27. Glumes 3-7-veined, glume margins equal, 0.1-0.5 mm wide, widest at or slightly beyond midlength; lemmas unawned or with awns to 40 mm long. | → 28 |
28. Glumes 1.8-2.3 mm wide, margins 0.2-0.3 mm wide | E. trachycaulus |
28. Glumes 0.4-1.5(2) mm wide, margins 0.1-0.2 mm wide | E. glaucus |
1. Spikelets 2-3(5) at all or most nodes; glumes often with subterete to terete, indurate bases, sometimes with flat, non-indurate bases, glume bodies linear-lanceolate to setaceous or subulate, margins usually firm, sometimes hyaline or scarious; lemmas usually awned, awns up to 120 mm long [for opposite lead, see p. 290]. | → 29 |
29. Rachises disarticulating at maturity; glumes 10-135 mm long including the awns, sometimes split longitudinally, flexuous to outcurving from near the base; lowest floret in each spikelet sometimes sterile; blades 1-6 mm wide. | → 30 |
30. Glume awns split into 3-9 divisions; lemma awns about 0.2 mm wide at the base; rachis internodes 3-5 mm long | E. multisetus |
30. Glume awns entire or split into 2-3 divisions; lemma awns about 0.4 mm wide at the base; rachis internodes 3-10(15) mm long | E. elymoides |
29. Rachises not disarticulating at maturity; glumes 0-43 mm long including the awns, entire, straight or outcurving from well above the base; lowest floret in each spikelet functional; blades 2-25 mm wide. | → 31 |
31. Glume bodies with 0-1(2) veins, linear or tapering from the base, 0.1-0.6 mm wide, 0-24 mm long including the awns, often differing in length by more than 5 mm, persistent after the florets disarticulate; rachis internodes 0.1-0.3(0.4) mm thick at the thinnest sections, often with green lateral bands. | → 32 |
32. Spikelets widely divergent to patent at maturity; lemma awns usually straight, rarely slightly curving; glumes vestigial or 1-3 mm long, occasionally some unequal glumes up to 10(20) mm long and 0.1-0.2 mm wide but with no distinct vein; spikes more or less erect | E. hystrix |
32. Spikelets usually appressed, never widely divergent; lemma awns straight or curving; glumes sometimes vestigial, usually 1-24 mm long, 0.1-0.6 mm wide, often with 1(2) distinct veins; spikes erect, nodding, or pendent. | → 33 |
33. Glumes 12-30 mm long including the awns, subequal; lemma awns straight to moderately curving; spikes erect to slightly nodding. | → 34 |
34. Spikelets (6)9-15(22) mm long excluding the awns, each with 2-5 florets; lemma awns moderately outcurving at maturity; glumes (0.2)0.3-0.5(0.7) mm wide | E. interruptus |
34. Spikelets 18-40 mm long excluding the awns, each with 3-8 florets; lemma awns straight to slightly curving at maturity; glumes 0.1-0.3(0.6) mm wide. | → 35 |
35. Anthers 2.5-4 mm long; lemmas scabrous-hispid to thinly strigose, at least distally; spikes 4-12 cm long; internodes 3-6 mm long, without green lateral bands, with hispid dorsal angles | E. pringlei |
35. Anthers 4.5-6 mm long; lemmas smooth, glabrous; spikes 9-20 cm long; internodes (5)7-15(22) mm long, with green lateral bands, glabrous except for the ciliolate margins | E. texensis |
33. Glumes 0-15(30) mm long including the awns, usually differing in length by at least 4 mm, 1 or both shorter than 12 mm, sometimes both essentially absent; lemma awns outcurving at maturity; spikes more or less nodding. | → 36 |
36. Rachis internodes 4-6(9) mm long; lemmas hirsute to strigose, at least near the margins, awns 20-35 mm long; sheaths glabrous; plants not glaucous or moderately glaucous | E. diversiglumis |
36. Rachis internodes (4)6-13(18) mm long; lemmas glabrous or pubescent, awns (8)10-30(35) mm long; sheaths glabrous or villous; plants usually glaucous, sometimes strongly so. | → 37 |
37. Lemmas usually glabrous, veins occasionally hispidulous near the apices, awns (8)10-20(25) mm long; spikelets with (3)4-5 florets; rachis internodes (4)6-10(12) mm long, without green lateral bands, glabrous; adaxial surfaces of the blades usually villous; plants strongly glaucous | E. svensonii |
37. Lemmas usually hairy, awns (10)20-30(35) mm long; spikelets with 3(5) florets; rachis internodes (5)7-13(18) mm long, with green lateral bands and hispid dorsal angles; adaxial surfaces of the blades glabrous or short-pilose; plants somewhat glaucous | E. churchii |
31. Glume bodies with 2-5(8) veins, widening or parallel-sided above the base, (0.2)0.3-2.3 mm wide, 4-43 mm long including the awns, equal or subequal, persistent or disarticulating; rachis internodes 0.1-0.8 mm thick at the thinnest sections, usually lacking green lateral bands. | → 38 |
38. Glumes bases more or less terete, indurate, and without veins for 0.5-4 mm; glume bodies exceeding the adjacent lemmas by 1-5 mm or indistinguishable from the glume awns; lemma awns usually straight, occasionally contorted on the lower spikelets; rachis internodes (1.5)2-5(8) mm long. | → 39 |
39. Glumes persistent, glume bodies (0.2)0.3-0.8(1) mm wide, with 2-4 veins, the basal 0.5-2 mm straight or slightly curving; lemmas with hairs or scabrous; spikelets with 1-3(4) florets; spikes nodding, exserted from the sheath. | → 40 |
40. Adaxial surfaces of the blades densely villous with fine whitish hairs, rarely just pilose on the veins, dark glossy green; spikes 4-12 cm long; internodes (1.5)2-3(4) mm long; spikelets with 1-2(3) florets; lemmas usually villous, sometimes glabrous, sometimes scabrous, 5.5-9 mm long, 0.5-1.5 mm longer than the paleas; anthesis usually in early June to early July | E. villosus |
40. Adaxial surfaces of the blades glabrous or scabrous, dull green; spikes 7-25 cm long; internodes 3-5(8) mm long; spikelets with 2-3(4) florets; lemmas hispidulous or scabrous, 7-14 mm long, 1-5 mm longer than the paleas; anthesis usually in late June to late July | E. riparius |
39. Glumes disarticulating, glume bodies (0.5)0.7-2.3 mm wide, with (2)3-5(8) veins, the basal 1-4 mm clearly bowed out; lemmas often glabrous, sometimes scabrous; spikelets with 2-5(6) florets; spikes erect, exserted or sheathed. | → 41 |
41. Spikes (0.5)0.7-2.2(2.5) cm wide including the awns, exserted or sheathed; glume awns 0-10(15) mm long; spikelets appressed to slightly spreading; blades usually glabrous or scabridulous. | → 42 |
42. Lemma awns 5-15(20) mm long at midspike; blades of all leaves usually spreading or lax and flat, those of the lower leaves not markedly larger or more persistent than those of the upper leaves; anthesis in mid-June to mid-August, usually 1-2 weeks earlier than sympatric E. curvatus | E. virginicus |
42. Lemma awns 0.5-3(4) mm long at midspike; upper blades usually ascending and somewhat involute, blades of the lower leaves relatively short, narrow, and senescing earlier than those of the upper leaves; anthesis usually in late June to early August, 1-2 weeks later than sympatric E. virginicus | E. curvatus |
41. Spikes (1.7)2.2-4.5(5.5) cm wide including the awns, exserted; glume awns (10)15-30 mm long; spikelets spreading; blades glabrous or villous. | → 43 |
43. Spikes with (6)9-16(20) nodes; internodes 4-7 mm long, about 0.3 mm thick at the thinnest portion; blades lax, dark glossy green under the glaucous bloom; auricles 2-3 mm long, often purplish black, at least in the central range of the species; anthesis usually in mid-May to mid-June | E. macgregorii |
43. Spikes with (10)18-30(36) nodes; internodes 3-5 mm long, 0.3-0.8 mm thick at the thinnest portion; blades lax, or ascending and involute, usually dull green, with or without a glaucous bloom; auricles 0-2 mm long, usually purplish brown; anthesis usually in mid-June to late July | E. glabriflorus |
38. Glume bases flat and veined or, if subterete to terete, indurate and without veins for less than 1 mm; glume bodies shorter than or subequal to the lowest lemmas; lemma awns usually flexuous to curving, sometimes straight; rachis internodes (2)3-14 mm long. | → 44 |
44. Glumes with more or less terete bases, without hyaline or scarious margins, always awned, awns (5)8-25(27) mm long or the glume bodies indistinguishable from the awns; spikelets (1)2-3(5) per node, spreading, not or rarely purplish; cauline nodes usually concealed by the sheaths. | → 45 |
45. Spikes erect to slightly nodding, internodes (5)8-14 mm long; glumes 0.2-0.5(0.7) mm wide; lemmas 7-10 mm long, usually smooth or scabrous, occasionally hirtellous, especially near the margins, awns 15-22 mm long, straight to moderately outcurving; blades 3-9 mm wide; culms (40)60-100(120) cm tall, nodes usually exposed | E. interruptus |
45. Spikes usually nodding to pendent, sometimes erect, internodes (2)3-8(12) mm long; glume bodies (0.2)0.4-1.6 mm wide; lemmas 8-15 mm long, glabrous or uniformly hairy, awns (10)15-40(50) mm long, moderately to strongly outcurving; blades 3-24 mm wide; culms (40)60-180(220) cm tall, nodes usually concealed by the leaf sheaths. | → 46 |
46. Rachis internodes (2)3-5(7) mm long; spikelets 2(3) at most nodes, occasionally 1 or up to 5 at some nodes; paleas acute; blades (3)4-15(20) mm wide, usually firm and somewhat involute, dull green, drying grayish | E. canadensis |
46. Rachis internodes 5-12 mm long; spikelets 2 per node; paleas narrowly truncate; blades (8)10-20(24) mm wide, flat, lax, dark green | E. wiegandii |
44. Glumes with flat bases and hyaline or scarious margins, usually awned, awns 1-10 mm long, sometimes unawned; spikelets (1)2(3) per node, appressed to divergent, sometimes purplish; cauline nodes mostly exposed. | → 47 |
47. Anthers 0.9-1.7 mm long; glumes 3-8 mm long; lowest lemmas 3-6 mm longer than the glumes, densely scabridulous to scabrous, awns usually outcurving; spikelets with (3)4-5(7) florets; spikes 2-5 cm wide, nodding to pendent; cauline nodes glabrous | E. sibiricus |
47. Anthers 1.5-4.5 mm long; glumes (4.5)6-14(19) mm long; lowest lemmas from shorter than to 2.5 mm longer than the glumes, smooth, sometimes hairy, awns straight, flexuous, or outcurving; spikelets with 2-4(7) florets; spikes (0.2)0.5-2.5 cm wide, erect, nodding, or pendent; cauline nodes occasionally with short hairs. | → 48 |
48. Glume bodies (6)9-14(19) mm long; lemmas 8-16 mm long, awns usually straight to flexuous; auricles usually present, to 2.5 mm long | E. glaucus |
48. Glume bodies (4.5)6-10(11) mm long; lemmas 5-14 mm long, awns flexuous to moderately outcurving; auricles often absent, or to 1.5 mm long. | → 49 |
49. Lemmas with hairs, the marginal hairs markedly longer than those elsewhere; paleas acute; spikes nodding to pendent; rachis internodes 3-12 mm long; leaves usually deep green; plants native to the Pacific coastal mountains | E. hirsutus |
49. Lemmas smooth, scabrous, or hispid, the marginal hairs, if present, not markedly longer than those elsewhere; paleas obtuse or truncate; spikes erect to slightly nodding; rachis internodes 3-6 mm long; leaves usually pale green, sometimes glaucous; plants introduced | E. dahuricus |