1	"Spikelets 2-7 at all or most nodes."	2
1	"Spikelets 1 at all or most nodes."	7
2	"Spikelets 3 at each node, the central spikelets usually sessile, sometimes pedicellate, the pedicel to 2 mm long, lateral spikelets usually pedicellate, sometimes all 3 spikelets sessile in cultivated plants; spikelets with 1 floret, usually only the central spikelet with a functional floret, the florets of the lateral spikelets usually sterile and reduced, in cultivated plants all florets functional or those of the lateral spikelets functional and those of the central spikelet reduced"	Hordeum
2	"Spikelets usually other than 3 at each node, if 3, all three sessile; spikelets with 1–11florets, if 1 floret, usually additional reduced or sterile florets present distal to the functional floret in at least 1 spikelet per node"	3
3	"Plants annual, weedy; spikelets with only 1 bisexual floret"	"Taeniatherum {Taeniatherum caput-medusae}"
3	"Plants perennial, usually not weedy; spikelets usually with more than 1 bisexual floret"	4
4	"Lemma awns (0)1–120 mm long; anthers 0.9–6 mm long; blades with well-spaced, unequally prominent veins on the adaxial surface"	5
4	"Lemmas usually unawned or with awns up to 7 mm long, if awns 16–35 mm long, anthers 6–8 mm; blades usually with closely spaced, equally prominent veins on the adaxial surfaces"	6
5	"Palea keels not winged, the intercostal tissue truncate or shorter in the center; spikes usually not drooping; native in much of North America"	Elymus
5	"Palea keels winged, the intercostal tissue rounded and extending beyond the keels; spikes drooping; introduced to North America, known to be established in and around Raleigh, North Carolina"	"Campeiostachys {Campeiostachys tsukushiensis}"
6	"Disarticulation in the spikelets, beneath the florets; plants sometimes cespitose, often rhizomatous"	Leymus
6	"Disarticulation tardy, in the rachises; plants cespitose, not rhizomatous"	"Psathyrostachys {Psathyrostachys juncea}"
7	"Spikelets usually more than 3 times the length of the middle rachis internodes, usually divergent, sometimes ascending; rachis internodes 0.2–5.5 mm long"	8
7	"Spikelets 1/2–3 times the length of the rachis internodes, appressed or ascending; rachis internodes 3–28 mm long"	11
8	"Glumes with 2 prominent keels, keels with tufts of hair"	"Dasypyrum {Dasypyrum villosum}"
8	"Glumes usually 1 keeled, sometimes 2-keeled at maturity, keels glabrous, scabrous or hairy, hairs never in tufts"	9
9	"Plants perennial; anthers 3–5 mm long; spikes 1.3–15 cm long"	Agropyron
9	"Plants usually annual, ometimes biennial or short-lived perennials; anthers 0.4–1.4 mm or about 7 mm long; spikes 0.8–4.5 cm long"	10
10	"Lemmas strongly keeled, keels conspicuously scabrous distally, scabrules 0.5–0.8 mm long; spikelets with 2 subequal florets; anthers about 7 mm long;"	Secale
10	"Lemmas weakly keeled, keels at most inconspicuously keeled, the scarules less than 0.5 mm long; spikelets with 2 or more florets, lower florets smaller than those above; anthers 0.4–1.4 mm long"	Eremopyrum
11	"Glumes subulate to narrowly lanceolate, tapering from below midlength, 1(3)-veined at midlength"	12
11	"Glumes lanceolate, rectangular, ovate, or obovate, narrowing beyond midlength, often the in distal 1/4, (1)3–5(7)-veined at midlength"	13
12	"Glumes lanceolate, tapering to acuminate apices from near midlength or below, keels curving to the side distally; plants always rhizomatous"	"Pascopyrum {Pascopyrum smithii}"
12	"Glumes subulate to lanceolate, tapering from below midlength, keels straight or almost so; plants often rhizomatous"	Leymus
13	"Plants annual; glumes often with lateral teeth or awns, midveins smooth throughout"	14
13	"Plants perennial; glumes without lateral teeth or awns, midveins sometimes scabrous"	15
14	"Glumes rounded over the midveins; plants weedy"	Aegilops
14	"Glumes keeled over the midveins; plants cultivated, sometimes escaping"	Triticum
15	"Glumes stiff, truncate, obtuse, or acute, unawned; glume keels smooth proximally, usually scabrous distally"	Thinopyrum
15	"Glumes flexible, acute to acuminate, sometimes awn-tipped; glume keels usually uniformly smooth or scabrous their whole length, sometimes smooth proximally and scabrous distally"	16
16	"Spikelets distant, not or scarcely reaching the base of the spikelet above on the same side of the rachis; anthers 4–8 mm long"	"Pseudoroegneria {Pseudoroegneria spicata}"
16	"Spikelets usually more closely spaced, reaching midlength of the spikelet above on the same side of the rachis; anthers 0.7–7 mm long"	17
17	"Paleas subequal to the lemma bodies; palea keels not conspicuously scabrous distally; established in much of North America"	Elymus
17	"Paleas shorter than the lemma bodies; palea keels conspicuously scabrous distally, intercostal region rounded; not known to be established in North America"	Roegneria