1	Upper lemma with an awn and 2 lateral bristles; pedicels often with stiff hairs at apex (if lateral bristles absent, lemma bidentate and pedicels with apical hairs)		(2)
+	Upper lemma awnless or with a single awn, lateral bristles absent; pedicels without stiff hairs at apex		(5)
2 (1)	Awn almost straight; nodes concealed in leaf sheaths, bearded.		1 A. barbinodis
+	Awn clearly geniculate; nodes exposed, glabrous or bearded		(3)
3 (2)	Culms 0.2–0.5 m tall, 0.5–1.5 mm in diam.; leaf blades 1–2 mm wide; spikelets 4.5–5.5 mm.		2 A. nodosa
+	Culms (0.5–)1–2.5 m tall, 1.5–5 mm in diam.; leaf blades 3–9 mm wide; spikelets (3–)5–8 mm		(4)
4 (3)	Panicle loose; nodes usually glabrous (bearded in var. tengchongensis which has spikelets 3–3.5 mm); spikelets (3–)5–6.5 mm, usually glabrous		3 A. setosa
+	Panicle contracted, dense; nodes woolly; spikelets 6–8 mm, usually with tubercle-based hairs.		4 A. khaseana
5 (1)	Upper lemma not awned, or awn very short and inconspicuous (2.5 mm or less)		(6)
+	Upper lemma awned, awn conspicuous, projecting from spikelet		(9)
6 (5)	Upper lemma 2.5–3.5 mm; awn absent or a straight mucro up to 1.5 mm		(7)
+	Upper lemma 1.3–2.5 mm; caducous awn present on some spikelets, geniculate, up to 2.5 mm		(8)
7 (6)	Plant with spreading scaly rhizomes; culms 2–5 mm in diam.; leaf blade (4–)7–15 mm wide.		5 A. hirta
+	Plant with short rhizomes; culms 1–2 mm in diam.; leaf blade 4–6 mm wide.		6 A. fluviatilis
8 (6)	Culms to 2 m or more, stout; panicle 30–70 cm, lower branches 12–30 cm; spikelets 3.5–4 mm		7 A. decempedalis
+	Culms to 1 m, more slender; panicle 7–30 cm, lower branches 2–7 cm; spikelets 2.5–3.5 mm.		8 A. bengalensis
9 (5)	Glumes setose with stiff tubercle-based hairs on veins; panicle densely contracted or spikelike, usually less than 12 cm		(10)
+	Glumes glabrous or hispidulous on veins; panicle open or loosely contracted, (8–)15–60 cm		(12)
10 (9)	Axis of panicle densely pubescent; spikelets purplish.		9 A. hookeri
+	Axis of panicle scabrid; spikelets yellowish brown or grayish red		(11)
11 (10)	Leaf blades leathery, glabrous; culms branched at lower nodes; panicle branches less than 7 cm; spikelets yellowish brown.		10 A. flavida
+	Leaf blades papery, hispid; culms unbranched; panicle branches up to 18 cm; spikelets purplish.		11 A. tricholepis
12 (9)	Culms 1–3 m; panicle 20–60 cm		(13)
+	Culms less than 1 m tall; panicle 5–30 cm (to 50 cm in A. longispicata)		(15)
13 (12)	Spikelets 2–2.8 mm.		12 A. parviflora
+	Spikelets 3.5–7 mm		(14)
14 (13)	Leaf blades 0.5–1.5 cm wide; panicle open or loosely contracted, central axis visible, branches ascending, loosely spiculate.		13 A. nepalensis
+	Leaf blades 1–2.5 cm wide; panicle dense, central axis concealed, branches suberect, densely spiculate.		14 A. cochinchinensis
15 (12)	Panicle 30–50 cm, lowest branch to 20 cm.		15 A. longispicata
+	Panicle 5–30 cm, lowest branch to 8(–15) cm		(16)
16 (15)	Spikelets 6–7 mm; culms loosely tufted, with scaly rhizomes.		16 A. grandiflora
+	Spikelets 3.5–5.2 mm; culms densely tufted, with or without rhizomes		(17)
17 (16)	Panicle branches smooth or almost so; callus hairs 1/2 length of lemma; mountain meadows.		17 A. yunnanensis
+	Panicle branches usually scabrid or hispidulous; callus hairs 1/4–1/3(–1/2) lemma length; river banks and floodlands		(18)
18 (17)	Culms 15–35 cm tall; leaves mainly basal; nodes bearded; panicle branches almost smooth.		18 A. pubescens
+	Culms 30–80 cm tall; leaves cauline; nodes glabrous or pubescent; panicle branches hispidulous		(19)
19 (18)	Plant not rhizomatous; callus hairs 1/4–1/3 length of lemma.		19 A. rupestris
+	Plant strongly rhizomatous; callus hairs 1/2 length of lemma.		20 A. intricata