1	Spikelet usually cylindric or narrowly ellipsoid, as wide as culms; culms usually stout, sometimes transversely septate with nodes evident on surface (in E. dulcis); leaf sheath mouth oblique; glumes firm, subcartilaginous, rarely subpapery or membranous, midvein obscure or indistinct but with 15 or more prominent to obscure close longitudinal veins		(2)
+	Spikelet ovoid to narrowly ovoid, rarely cylindric, usually wider than culms; culms slender, nodes not evident on surface; leaf sheath mouth truncate or slightly oblique, rarely with a scarious appendage; glumes generally membranous, midvein distinct or rarely obscure		(7)
2 (1)	Culms with transverse septa, nodes evident on surface when dry; spikelet with basal 2 glumes empty, rarely 1 with a flower; nutlet surface essentially smooth.		1 E. dulcis
+	Culms without transverse septa, nodes not evident on surface when dry; spikelet with only basalmost glume empty; nutlet surface cancellate or reticulate		(3)
3 (2)	Culms terete.		6 E. ochrostachys
+	Culms 3-angled, rarely acutely 4- or 5-angled		(4)
4 (3)	Culms firm, with pith in center; glumes broadly ovate or subquadrate, as long as wide		(5)
+	Culms spongy, subhollow; glumes narrowly ovate or broadly lanceolate, ca. 2 × as long as wide		(6)
5 (4)	Leaf sheath mouth with setaceous appendage; glumes densely imbricate, subquadrate, apex truncate; nutlet apex not constricted; perianth bristles as long as or shorter than nutlet.		2 E. spiralis
+	Leaf sheath mouth acute but without an appendage; glumes laxly imbricate, broadly ovate, apex rounded; nutlet apex constricted; perianth bristles ca. 2 × as long as nutlet.		3 E. trilateralis
6 (4)	Culms 3-angled, (1-)3-4 mm thick; spikelet 1.5-4 cm × 3-5 mm; glumes broadly ovate, 3-3.5 mm wide, subleathery, apex rounded; nutlet surface shallowly pitted with 13-15 longitudinal rows of transversely oriented, oblong to linear epidermal cells.		4 E. acutangula
+	Culms acutely 4- or 5-angled, 1.5-2.5 mm thick; spikelet 2-5 cm × 2.5-3 mm; glumes broadly lanceolate, 1.5-2.5 mm wide, membranous, apex obtuse to slightly acute; nutlet surface deeply pitted with 15-20 longitudinal rows of hexagonal epidermal cells.		5 E. philippinensis
7 (1)	Persistent style base scarcely differentiated from nutlet apex and seemingly a continuation of it		(8)
+	Persistent style base differentiated from nutlet apex by a constriction or articulation at junction with it		(10)
8 (8)	Annuals, neither stoloniferous or rhizomatous; culms often recurved; persistent style base pyramidal-acuminate; nutlet narrowly winged on angles, reticulate to deeply pitted-reticulate with isodiametric epidermal cells		9 E. retroflexa
+	Perennials, stoloniferous; culms erect to ascending; persistent style base triangular-subulate or subconic; nutlet not winged on angles, essentially smooth		(9)
9 (8)	Culms 1-7 cm tall; spikelets 2-4 mm, 6-10-flowered; persistent style base triangular-subulate; nutlet. 9-1.5 mm, smooth.		7 E. parvula
+	Culms 3-30 cm tall; spikelets 4-7 mm, 2-7-flowered; persistent style base subconic to 3-angled-subulate; nutlet 1.9-2.5 mm, appearing smooth but finely cellular-reticulate.		8 E. quinqueflora
10 (7)	Stigmas 3		(11)
+	Stigmas 2		(19)
11 (10)	Culms short and very slender; spikelet few flowered; glumes subdistichous at base of spikelet; nutlet terete or nearly so, longitudinally ridged with ridges separated by numerous cross-walls (trabeculae).		10 E. yokoscensis
+	Culms elongate and ± stout; spikelet many flowered; glumes spirally imbricate; nutlet 3-sided to compressed 3-sided, essentially smooth		(12)
12 (11)	Culms acutely (3 or)4(-6)-angled; spikelet not proliferous at base; nutlet brownish when mature		(13)
+	Culms terete; spikelet usually proliferous at base; nutlet olivaceous or yellowish when mature		(14)
13 (12)	Glumes 3-4 × 1-1.5 mm, margin narrow and hyaline; nutlet 1.2-1.5 mm and as wide; perianth bristles laxly to densely retrorsely spinulose; persistent style base deltoid, 1/2-2/3 as long as nutlet.		11 E. tetraquetra
+	Glumes 4-6 × 2-2.5 mm, margin broad and hyaline; nutlet 1.5-2 mm and as wide; perianth bristles plumose with spreading hairs; persistent style base narrowly ovoid, as long and as wide as nutlet or nearly so.		12 E. wichurae
14 (12)	Glumes ovate-lanceolate, 3-4 mm, apex acute; persistent style base narrowly 3-angled to conic, attenuate to a short caudal tip, ca. 1/2 as long as nutlet; rhizome decumbent or obliquely ascending.		13 E. yunnanensis
+	Glumes oblong, suboblong, ovate, or elliptic, 1.5-2.5 mm, apex obtuse or rounded; persistent style base 3-angled, pyramidal, deltoid, narrowly ovoid, or subconic, ca. 1/4 as long as nutlet; rhizome absent or present		(15)
15 (14)	Persistent style base depressed, deltoid-pyramidal, as wide as nutlet or nearly so.		17 E. attenuata
+	Persistent style base not depressed, deltoid, narrowly ovoid, or subconic, often shortly attenuate to apex, ca. 1/2 as wide as nutlet		(16)
16 (15)	Perianth bristles exceeding tip of style base.		18 E. congesta
+	Perianth bristles shorter than tip of style base		(17)
17 (16)	Annuals; spikelet narrowly ovoid, oblong-ovoid, cylindric, or rarely globose-ovoid, (3-)5-10 mm, several to many flowered; glumes oblong.		14 E. pellucida
+	Perennials; spikelet ovoid or ovoid-cylindric, 2.5-6 mm, few flowered; glumes ovate or elliptic		(18)
18 (17)	Perianth bristles 6, slightly shorter than nutlet; nutlet obovoid, ca. 1 mm.		15 E. maximowiczii
+	Perianth bristles 2-5, 1/4-1/2 as long as nutlet; nutlet oblong to oblong-obovoid, ca. 1.5 mm.		16 E. setulosa
19 (10)	Annuals; persistent style base not spongy-thickened; stolons absent; spikelet ovoid, subglobose, or oblong-ovoid, (2-)3-5(-8) mm		(20)
+	Perennials; persistent style base spongy-thickened but rarely obscurely so; stolons often present; spikelet narrowly ovoid, narrowly oblong-ovoid, or ellipsoid-cylindric, (3-)7-25 mm		(22)
20 (19)	Persistent style base dorsiventrally compressed, deltoid; nutlet brownish at maturity.		19 E. ovata
+	Persistent style base depressed conic or saucer-shaped; nutlet black at maturity and lustrous		(21)
21 (20)	Nutlet 0.7-1.1 mm; perianth bristles 6-8, rust-colored; persistent style base depressed conic, slightly reflexed basally on both sides.		20 E. geniculata
+	Nutlet 0.3-0.6 mm; perianth bristles 4-6, colorless or white; persistent style base saucer-shaped, not reflexed basally.		21 E. atropurpurea
22 (19)	Basalmost glume empty, suborbicular, spathiform, usually completely encircling base of spikelet		(23)
+	Basal 2 or 3 glumes empty, basalmost encircling 1/2 or less of spikelet base		(28)
23 (22)	Persistent style base large, mitriform, cellular-spongy, ovoid, more than 2/3 to as long as nutlet.		30 E. kamtschatica
+	Persistent style base conic, broadly ovoid, deltoid, 3-angled, or depressed, less than 1/2 as long as nutlet		(24)
24 (23)	Persistent style base depressed, subpatelliform (disk-shaped).		31 E. fennica
+	Persistent style base shallowly conic-ovoid, obtusely 3-angled, low conic, or shortly 3-angled		(25)
25 (24)	Glumes oblong-ovate to oblong-lanceolate; persistent style base shallowly conic-ovoid, nearly as long as wide, nearly 1/2 as long as nutlet.		32 E. uniglumis
+	Glumes ovate; persistent style base obtusely 3-angled or low conic, shorter than or nearly as long as wide, 1/4-1/3 as long as nutlet		(26)
26 (25)	Persistent style base obtusely 3-angled, nearly as long as wide, ca. 1/3 as wide as nutlet; perianth bristles 4, slightly longer than nutlet.		33 E. penchaoi
+	Persistent style base low conic or shortly 3-angled, shorter than wide, ca. 1/2 as wide as nutlet; perianth bristles 4-6, slightly shorter to slightly longer than nutlet		(27)
27 (26)	Culms 8-25 cm tall; spikelet 3-4 mm wide; glumes ovate to broadly ovate, ca. 3 mm, apex acute; perianth bristles as long as or slightly longer than nutlet.		34 E. erhaiensis
+	Culms 25-30 cm tall; spikelet 2-3 mm wide; glumes ovate to oblong-ovate, ca. 4 mm, apex obtuse; perianth bristles slightly shorter than nutlet.		35 E. qinghaiensis
28 (22)	Persistent style base oblong-ovoid to oblong-conic, much longer than wide.		29 E. palustris
+	Persistent style base shortly conic, globose-ovoid, broadly ovoid, subquadrate, or globose, as wide as or wider than long		(29)
29 (28)	Leaf sheaths scarious (at least apical ones), mouth with a deep sinus ventrally.		26 E. argyrolepis
+	Leaf sheaths herbaceous, mouth truncate to obliquely truncate		(30)
30 (29)	Spikelet broadly ovoid to oblong, 3-8 mm, few flowered.		27 E. abnorma
+	Spikelet oblong to oblong-lanceolate, (7-)10-30 mm, many flowered		(31)
31 (30)	Glume apices obtuse to subrounded; persistent style base broadly ovoid, rounded-ovoid, subquadrate, or globose		(32)
+	Glume apices acute to subacute; persistent style base shortly conic, conic, or globose		(33)
32 (31)	Glumes ovate to oblong-ovate; nutlet globose-obovoid; persistent style base broadly ovoid.		28 E. valleculosa
+	Glumes oblong to linear-oblong; nutlet usually ellipsoid; persistent style base globose-ovoid to subquadrate.		22 E. liouana
33 (31)	Persistent style base globose or wider than long, mammiform or mitriform (cap-shaped).		25 E. mitracarpa
+	Persistent style base shortly conic to conic		(34)
34 (33)	Glumes oblong-lanceolate; nutlet obovoid,. 7-0.8 mm wide; persistent style base narrowly conic.		23 E. migoana
+	Glumes ovate to oblong-ovate or ovate-lanceolate; nutlet broadly obovoid to orbicular-obovoid, 1-1.3 mm wide; persistent style base depressed conic or shortly conic.		24 E. ussuriensis