1	Florets disarticulating from above downward, falling together with the rachilla joints		(2)
+	Florets disarticulating from below upward, usually leaving the rachilla entire		(7)
2 (1)	Panicle contracted, spikelike or cylindrical		(3)
+	Panicle usually open		(4)
3 (2)	Perennial; lemmas 1.8–2.5 mm, ciliolate along the margins below.		27 E. ciliata
+	Annual; lemmas 0.8–1.3 mm, glabrous or scabrous along the margins.		28 E. ciliaris
4 (2)	Perennial.		29 E. collina
+	Annual		(5)
5 (4)	Palea-keels long ciliate; branchlets and pedicels glandular.		30 E. tenella
+	Palea-keels glabrous to ciliolate; branchlets and pedicels eglandular		(6)
6 (5)	Culms 120–150 cm tall, ca. 5 mm in diam.; panicle branches solitary or in pairs; spikelets yellowish green		31 E. alta
+	Culms 30–100 cm tall, 1.5–2.5 mm in diam., panicle branches clustered or verticillate; spikelets purplish at maturity		32 E. japonica
7 (1)	Annual		(8)
+	Perennial		(17)
8 (7)	Palea falling together with its lemma at maturity		(9)
+	Palea persistent or tardily falling		(11)
9 (8)	Spikelets oblong, 5–10 × 2–4 mm, 10–20-flowered.		25 E. unioloides
+	Spikelets filiform, 11–25 × 1–2.5 mm, 10–40-flowered		(10)
10 (9)	Upper glumes ca. 1 mm; lower lemma ca. 1.5 mm; palea ca. 1 mm; anthers ca. 0.2 mm.		20 E. multicaulis
+	Upper glumes 1.3–2.3 mm; lower lemma 1.8–2.2 mm; palea ca. 1.6–1.8 mm; anthers 0.7–0.9 mm.		7 E. atrovirens
11 (8)	Plants glandular on the culms, leaf sheaths, and panicle		(12)
+	Plants eglandular		(14)
12 (11)	Spikelets 2–3 mm broad, lower lemma 2.2–2.8 mm.		22 E. cilianensis
+	Spikelets 1.5–2.5 mm broad, lower lemma 1.5–2 mm		(13)
13 (12)	Palea subequal to its lemma; midrib of lemma glandular.		23 E. minor
+	Palea shorter than its lemma; midrib of lemma eglandular.		24 E. suaveolens
14 (11)	Lower glume 1-veined, 1–2 mm, the upper ca. 2 mm		(15)
+	Lower glume without a vein, less than 1 mm, the upper less than 1.4 mm		(16)
15 (14)	Spikelets 5–20 × 2–2.5 mm, 8–40 florets.		16 E. cumingii
+	Spikelets 3–5 × ca. 2 mm, 3–10 florets.		21 E. autumnalis
16 (14)	Summit of sheaths pilose; panicles 3.5–14 cm wide, axils pilose; pedicels as long or longer than the spikelets.		19 E. pilosa
+	Summit of sheaths glabrous; panicles 1.5–3 cm wide, axils glabrous; pedicels usually shorter than the spikelets.		20 E. multicaulis
17 (7)	Lemma falling together with the palea at maturity		(18)
+	Palea persistent or tardily falling at maturity		(19)
18 (17)	Spikelets 2–4 mm wide; stamens 2, anthers 0.2–0.5 mm; leaf blades sublanceolate, 3–6 mm broad.		25 E. unioloides
+	Spikelets 1.5–2.5 mm wide; stamens 3, anthers 0.7–0.9 mm; leaf blades linear, 2–4 mm broad.		7 E. atrovirens
19 (17)	Panicle contracted and spikelike, less than 3(–5) cm wide		(20)
+	Panicle open, usually more than 3 cm wide		(22)
20 (19)	Spikelets 1–2 mm broad; lower panicle branches (1.5–)3–8 cm.		4 E. nutans
+	Spikelets 2–3 mm broad; lower panicle branches 0.5–2.5 cm		(21)
21 (20)	Palea apex acute, the keels ciliate but not winged; panicle 2–8 cm, pilose in axils.		5 E. cylindrica
+	Palea apex toothed, the keels winged, ciliolate along the wings; panicle 10–15 cm, glabrous in axils.		6 E. nevinii
22 (19)	Branchlets and pedicels distinctly or obscurely glandular		(23)
+	Branchlets and pedicels eglandular		(24)
23 (22)	Caryopsis rectangular-prismatic with a shallow adaxial groove, laterally compressed, 0.7–1.5 mm.		15 E. ferruginea
+	Caryopsis obovoid to ellipsoid, terete, without a groove, 0.7–0.9 mm.		13 E. perennans
24 (22)	Branches densely spiculate to base		(25)
+	Branches naked at base		(26)
25 (24)	Stamens 3, anthers 0.3–1.3 mm; caryopsis dark brown.		1 E. brownii
+	Stamens 2, anthers 0.2–0.3 mm; caryopsis cinnamon.		2 E. elongata
26 (24)	Leaf blades long pilose on both surfaces		(27)
+	Leaf blades glabrous, pubescent or pilose in part		(28)
27 (26)	Spikelets 7–14-flowered; caryopsis furrowed on one side, bluntly triangular in section.		10 E. pilosissima
+	Spikelets usually 7-flowered; caryopsis compressed, elliptical in section.		11 E. pilosiuscula
28 (26)	Spikelets livid green, black-green, purplish black, or plumbeous; leaf sheaths compressed at the base		(29)
+	Spikelets purplish, yellowish, or greenish; leaf sheaths not compressed at the base		(34)
29 (28)	Culms 80–120 cm tall; leaf blades flat or involute, up to 40 cm; panicle up to 40 cm		(30)
+	Culms 30–80 cm tall; leaf blades flat or involute, 5–25 cm, panicle up to 23 cm		(31)
30 (29)	Caryopsis ellipsoid to obovoid, smooth and mostly translucent, dorsally compressed, adaxial surface sometimes with a shallow, broad groove, light brown.		9 E. curvula
+	Caryopsis rectangular-prismatic, faintly striate, laterally compressed, with a shallow, narrow groove, reddish brown		15 E. ferruginea
31 (29)	Plants with scaly buds at the base; spikelets 4–13 mm, 6–24-flowered		(32)
+	Plants without scaly buds at the base; 3–12-flowered		(33)
32 (31)	Lower glume ca. 1 mm; upper glume ca. 1.3 mm, 1–3-veined; caryopsis 0.8–1 mm.		16 E. cumingii
+	Lower glume ca. 1.2 mm; upper glume ca. 1.8 mm, 1-nerved; caryopsis 0.5–0.6 mm.		17 E. duricaulis
33 (31)	Spikelets 2–2.5 mm wide, 5–10 mm; lemmas 2–2.2 mm; caryopsis elliptical, terete		14 E. nigra
+	Spikelets 1–1.5 mm wide, 3–6 mm; lemmas 2.4–3 mm; caryopsis rectangular-prismatic, laterally compressed.		15 E. ferruginea
34 (28)	Palea tardily deciduous at maturity; spikelets 7–15 mm, 10–44-flowered.		18 E. hainanensis
+	Palea persistent; spikelets 0.5–20 mm, 5–60-flowered		(35)
35 (34)	Axils of panicle and branches glabrous		(36)
+	Axils of panicle and branches pilose		(37)
36 (35)	Spikelets 5–10 × ca. 2.5 mm, 5–15-flowered; anthers ca. 0.5 mm.		8 E. fauriei
+	Spikelets 5–25 × ca. 3 mm, 6–60-flowered; anthers ca. 0.3 mm.		12 E. perlaxa
37 (35)	Culms 50–110 cm tall; panicle 20–35 cm; anthers ca. 1 mm.		13 E. perennans
+	Culms 20–60 cm tall; panicle 3–12 cm; anthers 0.2–0.4 mm		(38)
38 (37)	Leaf blades pilose on adaxial surface; lemmas with reddish or yellowish lateral veins.		3 E. rufinerva
+	Leaf blades glabrous; lemmas with inconspicuous lateral veins.		26 E. montana