1	"Stem nodes purple-black; floret staminate"	"Ventenata {Ventenata dubia}"
1	"Stem nodes green or straw-colored; floret bisexual"	2
2	"Glumes 0; palea 3-veined; plants of wet sites"	"Leersia {Leersia oryzoides}"
2	"Glumes 1 or 2; palea, when present, 2-veined; plants generally of drier sites (except <i>Oryza</i> and some <i>Phalaris</i>)"	3
3	"Lower glume awns 2"	"Muhlenbergia alopecuroides"
3	"Lower glume awn 0 or 1"	4
4	"Spikelets +- round, overlapping in 2 rows on 1 side of inflorescence branch; glumes winged, body transversely wrinkled"	"Beckmannia {Beckmannia syzigachne}"
4	"Spikelets not round, nor overlapping in 2 rows; glumes not winged, body smooth or veined, but not transversely wrinkled"	5
5	"Glumes ciliate-keeled"	6
5	"Glumes glabrous to sparsely hairy, but not ciliate-keeled"	7
6	"Glumes united at base; lemma awned; palea 0"	Alopecurus
6	"Glumes separate at base; lemma awnless; palea present"	Phleum
7	"Glumes unequal, tapering to a long point, +- swollen at base"	"Gastridium {Gastridium phleoides}"
7	"Glumes equal or unequal, but not tapering to long points, not swollen at base"	8
8	"Glumes keeled, often winged; floret subtended by a membranous flap or tuft of hairs"	Phalaris
8	"Glumes generally rounded, not winged; floret not subtended by a flap or tuft of hairs"	9
9	"Lemma generally hardened at maturity, margins generally overlapping and enclosing palea and grain; grain hardened, round in &times;-section; callus well-developed, blunt or sharp-pointed"	10
9	"Lemma and grain membranous or firm, but not hardened, generally flattened; callus not especially well-developed"	11
10	"Stem internodes +- solid; lemma veins 3, awns generally straight; ligule of hairs or basal membrane long-ciliate"	Aristida
10	"Stem internodes hollow; lemma veins 3--7, awns generally bent 1--2 &times;; ligule generally membranous"	Stipa
11	"Spikelet axis extended beside or above floret as a glabrous or hairy stub or bristle"	12
11	"Spikelet axis not extended beside or above floret"	15
12	"Spikelets breaking apart below glumes at maturity; stamens 1--2"	Cinna
12	"Spikelets breaking apart above glumes at maturity; stamens 3"	13
13	"Annual; callus glabrous to sparsely hairy"	Apera
13	"Annual or perennial herb from stolons or rhizomes; callus hairy"	14
14	"Inflorescence dense, cylindrical; spikelets 12--14 mm; lemma awn 0"	"Ammophila {Ammophila arenaria}"
14	"Inflorescence open, panicle-like; spikelets 2--4(11) mm; lemma awn 0.5--17 mm"	Calamagrostis
15	"Plants of flooded fields and in adjacent ditches; stamens 6"	"Oryza {Oryza sativa}"
15	"Plants terrestrial; stamens 1 or 3"	16
16	"Glumes with well-developed awns (except <i>Polypogon viridis</i>); spikelets breaking apart below glumes"	Polypogon
16	"Glumes acute, acuminate, or awn-tipped; spikelets breaking apart above glumes"	17
17	"Lemma vein 1, awn 0; leaf sheaths generally ciliate at tip; seed ejected from grain at maturity"	Sporobolus
17	"Lemma vein 3 or 5, awn present or 0; leaf sheaths not ciliate at tip; seed remaining within grain at maturity"	18
18	"Lemma veins 5(3), faint; palea generally 0 or << lemma"	Agrostis
18	"Lemma veins 3, generally obvious; palea generally well-developed"	Muhlenbergia