Elymus

Plants perennial; sometimes cespitose, sometimes rhizomatous, sometimes stoloniferous. Culms 8-180(220) cm, usually erect to ascending, sometimes strongly decumbent to prostrate, usually glabrous. Leaves usually evenly distributed, sometimes somewhat basally concentrated; sheaths open for most of their length; auricles often present; ligules membranous, usually truncate or rounded, sometimes acute, entire or erose, often ciliolate; blades 1-24(25) mm wide, abaxial surfaces usually smooth or scabrous, sometimes with hairs, adaxial surfaces scabrous or with hairs, particularly over the veins, usually with unequal, not strongly ribbed, widely spaced veins, sometimes with equal, strongly ribbed, closely spaced veins. Inflorescences spikes, usually exserted, with 1-3(5) spikelets per node, internodes (1.5)2-26 mm; rachises with scabridulous, scabrous, or ciliate edges. Spikelets usually appressed to ascending, sometimes strongly divergent or patent, with 1-11 florets, the lowest florets usually functional, sterile and glumelike in some species, the distal florets often reduced; disarticulation usually above the glumes and beneath each floret, sometimes also below the glumes or in the rachises. Glumes usually 2, absent or highly reduced in some species, usually equal to subequal, sometimes unequal, usually linear-lanceolate to linear, setaceous, or subulate, sometimes oblanceolate to obovate, (0)1-7-veined, sometimes keeled over 1 vein, not necessarily the central vein, keel vein sometimes extending into an awn; lemmas linear-lanceolate, obscurely 5(7)-veined, apices acute, often awned, sometimes bidentate, teeth to 0.2 mm, sometimes with bristles, bristles to 10 mm, awns terminal or from the sinus, straight or arcuately divergent, not geniculate; paleas from shorter than to slightly longer than the lemmas, keels scabrous or ciliate, at least in part; anthers 3, 0.7-7 mm. Caryopses with hairy apices, x = 7. Haplomes St, H, Y, P.

Distribution

Idaho, Mont., Nebr., N.C., Conn., N.J., N.Y., Mass., Wash., Va., W.Va., Ark., Iowa, Kans., Mo., N.Dak., Okla., S.Dak., Ariz., D.C, Ga., Ill., Ky., Mich., N.Mex., Pa., S.C., Tenn., Wyo., Del., Miss., Ind., Oreg., Maine, N.H., R.I., Vt., Ala., Fla., La., Md., N.S., Ohio, Tex., Wis., Colo., Calif., Alaska, Utah, Nev., Alta., B.C., Greenland, Man., N.B., Nfld. and Labr., N.W.T., Nunavut, Ont., P.E.I., Que., Sask., Yukon, Minn.

Discussion

Name from the Greek elyo, 'rolled up', the caryopses being tightly embraced by the lemma and palea.

All species of Elymus are alloploids that combine one copy of the St haplome present in Pseudoroegneria with at least one other haplome. So far as is known, all species that are native to North America, as well as many species native to northern Eurasia, are tetraploids with one additional haplome, the H genome from Hordeum sect. Critesion. Many Asian species combine the St haplome with the Y haplome, for which there are no known diploids; such species are sometimes placed in the segregate genus Roegneria. This treatment includes two such species, E. ciliaris and E. semicostatus. In addition, the treatment includes two hexaploid species, E. tsukusbiensis and E. dahuricus, that combine all three haplomes. Elymus repens and E. hoffmannii, the other two hexaploid species in this treatment, basically combine two copies of the St haplome with one of the H haplome, but the molecular data for E. repens point to a more complex situation (Mason-Gamer 2001). For further discussion of generic delimitation in the Triticeae, see Barkworth (2000), Yen et al. (2005), and Barkworth and von Bothmer (2005).

Elymus is sometimes divided into multiple sections (see, for example, Tsvelev 1976; Love 1984). There are, however, no detailed morphological descriptions of the sections, making it difficult to determine how to treat the North American species. It is notable that the species with solitary spikelets are concentrated in western and northern North America, whereas the species with multiple spikelets at a node are most prevalent east of the Rocky Mountains, from southern Canada to the Gulf Coast. There are exceptions to this statement. For instance, species with multiple spikelets and disarticulating rachises are primarily western in their distribution, yet E. glaucus, a species with multiple spikelets and non-disarticulating rachises, is western. Like the western species with solitary spikelets, and unlike most eastern species, its glumes have a hyaline margin.

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	Elymus 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	Elymus 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	Elymus arizonicus
6	Spikes erect to slightly nodding at maturity; rachis internodes 5-12 mm long; plants of the northwestern contiguous United States	Elymus 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	Elymus glaucus
8	Palea keels distinctly outwardly curved below the apices; apices 0.3-0.7 mm wide between the vein ends	Elymus 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	Elymus repens
10	Adaxial surfaces of the blades glabrous, veins smooth or scabrous, all veins more or less equally prominent; plants slightly to moderately rhizomatous	Elymus 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	Elymus 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	Elymus glaucus
12	Spikelets from shorter than to almost twice as long as the internodes; internodes 9-27 mm long; glumes unawned; blades usually straight	Elymus 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	Elymus 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	Elymus scribneri
15	Anthers 2-3.5 mm long; internodes 5-15 mm long; rachises not disarticulating; spikelets ascending to divergent	Elymus 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	Elymus 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	Elymus bakeri
19	Spikes 7-30 cm long, flexuous, nodding to pendent; blades 5-14 mm wide	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus glaucus
23	Spikes nodding to pendent, 2-5 cm wide	Elymus sibiricus
17	Lemmas unawned or with awns up to 7 mm long.	> 24
24	Plants strongly rhizomatous	Elymus 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	Elymus macrourus
26	Glumes 1.5-2 mm wide, oblanceolate to obovate, margins unequal; lemmas glabrous, evenly hairy, or more densely hairy distally	Elymus 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	Elymus 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	Elymus trachycaulus
28	Glumes 0.4-1.5(2) mm wide, margins 0.1-0.2 mm wide	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus 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	Elymus dahuricus

Elymus

Contents

Distribution

Discussion

Selected References

Lower Taxa

Key