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Elymus
See list of 11 species in this genusIn the following key, measurements of spike width include the awns. Collections of Elymus should include all of the aerial stem (i.e., collect at the ground level) so that the number of nodes can be accurately assessed. References: Haines (2000d), Barkworth et al. (2007).
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1a. Spikelets spreading to horizontally divergent at maturity; glumes obsolete or represented by veinless bristles up to 10 mm long (rarely longer in robust spikes) and 0.1–0.2 mm wide
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1b. Spikelets appressed to spreading-ascending; glumes present, with (1–) 2–7 veins, 6–40 mm long including the awn and 0.2–2.3 mm wide [Figs. 221,223,224]
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2a. Spikelets mostly solitary at each node of the spike; glumes 6–17 mm long including the awn
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3a. Anthers 3–7 mm long (i.e., plants outcrossing); plants rhizomatous; spikelets disarticulating below the glumes
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3b. Anthers 1–2 mm long (i.e., plants self-pollinating); plants cespitose, without rhizomes; spikelets disarticulating above the glumes
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2b. Spikelets 2–4 at each node of the spike, usually paired [Figs. 220,224]; glumes (7-)10–40 mm long including the awn
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4a. Awns arching at maturity, especially in late season and in drying; paleas 7–14 mm long; glumes thin or compressed at the base, indurate basally for up to 1 mm
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5a. Leaf blades thin, flat, short-pilose on the adaxial surface, (8–) 15–25 mm wide, numbering mostly 9–15 per reproductive stem; glumes 0.3–0.8 mm wide, with 1–3 (–5) veins; internodes of spike 5–8(–12) mm long; spikes often conspicuously drooping from near the base
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5b. Leaf blades firm, flat or involute, minutely scabrous on the adaxial surface (rarely pubescent), 3–15 mm wide, numbering mostly 5–9 per reproductive stem; glumes 0.5–1.6 mm wide, with 3–5 veins; internodes of spike (2–)3–5(–7) mm long; spikes nearly erect to arching
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4b. Awns straight or nearly so; paleas 5–10 (–12) mm long; glumes ± terete at the base, indurate basally for 0.5–4 mm
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6a. Glumes setaceous, only slightly broadened apically, 0.2–1 mm wide, straight or slightly bowed out at the base [Fig. 222]; spikes arching to nodding
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7a. Leaf blades softly villous or pilose on the adaxial surface; internodes of spike (1.5–) 2–3 (–4) mm long; lemmas usually villous, 5.5–9 mm long excluding the awns, 0–1.5 mm longer than the obtuse to emarginate paleas; spikelets with 1 or 2 (rarely 3) florets
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7b. Leaf blades glabrous or scabrous on the adaxial surface; internodes of spike 3–5 mm long; lemmas usually minutely scabrous, 7–14 mm long excluding the awns, 1–5 mm longer than the acute paleas; spikelets with 2 or 3 (rarely 4) florets
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6b. Glumes flattened above the base, 0.7–2.3 mm wide, slightly to strongly bowed out at the base and exposing the florets [Fig. 223]; spikes erect [Figs. 221,224]
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8a. Glumes including the awns 27–40 mm long, the glume awns 10–25 mm long; lemmas including the awns 35–50 mm long, the lemma awns (10–) 15–40 mm long; spikes 25–60 mm wide, usually exserted [Fig. 221]; spikelets spreading-ascending [Fig. 221]
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9a. Spikes with 15–30 nodes separated by internodes 3–5 mm long; auricles 0–2 mm long; glumes and lemmas often pubescent; plants of dry-mesic woodlands and forest openings
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9b. Spikes with 9–18 nodes separated by internodes 4–7 mm long [Fig. 221]; auricles 2–3 mm long; glumes and lemmas usually glabrous or minutely scabrous; plants of rich, mesic alluvium, less commonly on forested slopes
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8b. Glumes including the awns 7–27 mm long, the glume awns absent or up to 10 (–15) mm long; lemmas including the awns 6–30 mm long, the lemma awns absent or up to 5–15 (–20) mm long; spikes 7–20 mm wide, exserted or partly included in the upper leaf sheath [Figs. 220,224]; spikelets appressed to appressed-ascending
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10a. Awns absent or up to 3 (–5) mm long [Fig. 220]; leaf blades often ascending and somewhat involute, the lower frequently narrower and senescing earlier than the upper ones
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Each photo represents one species in this genus.