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Annual  or perennial herbs, rarely shrubs or tall woody bamboos. Flowering stems (culms) jointed, internodes hollow or solid. Leaves arranged alternately in 2 ranks, differentiated into sheath, blade, and  ligule, leaf-sheath split  or infrequently tubular, modified with reduced blade in bamboos, leaf-blades divergent, usually long, narrow and flat, varying from inrolled and filiform to ovate, veins usually parallel, ligule membranous or a line of hairs. Inflorescence terminal or solitary, open, contracted, or spikelike panicle, or composed of lax to spikelike raceme along an elongated central axis, or digitate, paired, or occasionally solitary, spikelets often aggregated into complex clusters in bamboos.

Key to the Genus

Serial Key Reference
1a. Herbs 2
1b. Bamboos with woody culms 73
2a. Spikelets 1-many flowered, if 2-flowered, then both bisexual or the upper barren, with rachilla extension in Dactyloctenium, Thysanolaena, 3 (Subfam. Pooideae)
2b. Spikelets 2-flowered, the lower floret male or barren, the upper fertile without rachilla extension 29 (Subfam. Panicoideae)
3a. Palea 1-keeled, glumes absent or minute or rudimentary 4
3b. Palea 2-keeled, rarely 0-1 keeled and then glumes well-developed 8
4a. Spikelets articulate on their pedicels and deciduous without pedicels 5
4b. Spikelets deciduous with their pedicels 7
5a. Lower glume and upper glume minute or setaceous; lower lemma and upper lemma chartaceous Oryza
5b. Lower glume and upper glume absent; lower lemma and upper lemma membranous 6
6a. Leaf-blades linear; both lower and upper lemma broad; upper lemma not awned Leersia
6b. Leaf-blades elliptic; both lower and upper lemma narrow, upper lemma awned Hygroryza
7a. Glumes long-awned; inflorescence of a spiciform raceme Perotis
7b. Glumes not awned; inflorescence of rigid erect spikes Zoysia
8a. Leaf-blades with distinct cross-nerves; broadly linear to ovate Centotheca
8b. Leaf-blades without evident cross-nerves 9
9a. Spikelets inserted in notches or of a smiple rachis/spike 10
9b. Spikelets not as above 12
10a. Spikelets in triads at the nodes of the spike Hordeum
10b. Spikelets solitary at the nodes of the spike 11
11a. Plane of the spikelets radial to the axis Oropetium
11b. Plane of the spikelets tangential to the axis Triticum
12a. Spikelets strictly 1-flowered Sporobolus
12b. Spikelets 2-or more flowered 13
13a. Inflorescence of a strongly compressed, long, cylindrical, continuous or interrupted catkin-like spike bearing spikelets in globose clusters Elytrophorus
13b. Inflorescence of open panicles or digitate or sub-digitate spikes or racemes 14
14a. Inflorescence of an inarticulate spike or raceme with 2-seriate and secund spikelets, or of a spiciform panicle 15
14b. Inflorescence of open or contracted panicle, or if spicate not secund 21
15a. Spikelets on the long, spiciform branches of a raceme Leptochloa
15b. Spikelets in simple digitate or simply racemed spikes 16
16a. Spikelets 1- flowered 17
16b. Spikelets 2- or more flowered 18
17a. Spikelets awnless; spikes digitate Cynodon
17b. Spikelets awned; spikes solitary, spicate or racemed Chloris
18a. Rachis of spike terminating in a fertile spikelet. Spike digitate or subdigitate Eleusine
18b. Rachis of spike not terminating in a spikelet, with or without rachis extension 19
19a. Spikes with rachis extension. Paired or digitate spikes Dactyloctenium
19b. Spikes without rachis extension 20
20a. Florets 2, dissimilar, the lower awnless, male or barren; spikelets falling entire, subterete Arundinella
20b. Florets 2 to many, similar except the uppermost-which are gradually reduced Eriachne
21a. Large, stout plants with large compound panicles 22
21b. Plants shorter 25
22a. Spikelets with 1 fertile floret; rachilla produced beyond the upper floret Thysanolaena
22b. Spikelets with 2 or more fertile florets; rachilla not produced beyond the upper floret 23
23a. Rachilla glabrous; flowering glumes dorsally hairy beyond the middle Arundo
23b. Rachilla hirsute 24
24a. Lemmas glabrous Phragmites
24b. Lemmas penicillate with long hairs Neyraudia
25a. Lemmas 5-15 nerved; inflorescence capitate or globular head of spikelets; leaves rigid, pungent Aeluropus
25b. Lemmas 1-3 nerved; inflorescence and leaves not as above 26
26a. Upper lemma indurated or crisply chartaceous Isachne
26b. Upper lemma membranous 27
27a. Racemes deciduous; glumes tapering to a long subulate awn Myriostachya
27b. Racemes persistent; glumes acute, not awned 28
28a. Spikelets sessile; falling entire Desmostachya
28b. Spikelets pedicelled, vaiously disarticulating; not falling entire Eragrastis
29a. Spikelets paired (except solitary in Dimeria and Arthraxon), one sessile the other pedicelled, usually dissimilar, the pedicelled sometimes much reduced, rarely single and then either in fragile racemes or the upper lemma geniculatehy awned (some exceptions in Dimeria); lower glume as long as spikelet or almost so 30 (Andropogo neae)
29b. Spikelets never paired (Echinohloa); nor in fragile racemes, nor geniculately awned 55 (Paniceae)
30a. Spikelets not paired, unaccompanied by a vestige 31
30b. Spikelets paired, 32
31a. Raceme rachis tough, not jointed Dimeria
31b. Raceme rachis fragile, jointed Arthraxon
32a. Spikelets unisexual, with male and female spikelets in separate inflorescences or in different parts of the same inflorescence 33 (Maydeae)
32b. Spikelets, or at least one of each pair, bisexual 35
33a. Internodes broader than and more or less enclosing female spikelet Zea
33b. Internode narrower than and more or less enclosed by female spikelet 34
34a. Sheath subtending raceme herbaceous Chionachne
34b. Sheath subtending racemes indurated and forming an ovoid utricle around the female spikelet Coix
35a. Rachis internodes and pedicels stout, thickening upwards; upper lemma, awnless; pedicels fused to internode, 36
35b. Rachis internodes and pedicels slender, sometimes thickened upwards but then the upper lemma awned or the callus rufously bearded; pedicels free from internodes 39
36a. Pedicelled spikelet absent Mnesithea
36b. Pedicelled spikelet present 37
37a. Rachis of raceme tough Hemarthria
37b. Rachis of raceme fragile 38
38a. Sessile spikelet globose Hackelochloa
38b. Sessile spikelet not globose Rottboellia
39a. Pedicelled spikelet similar to the sessile, both fertile 40
39b. Pedicelled spikelet differing from the sessile in shape and sex 44
40a. Inflorescence a panicle, with elongated central axis 41
40b. Inflorescence of single or subdigitate raceme 43
41a. Raceme rachis fragile; one spikelet of the pair sessile. Panicle ample Saccharum
41b. Raceme rachis tough; both spikelets pedicelled 42
42a. Panicle loose; glumes cartilagenous to coriaceous Miscanthus
42b. Panicle contracted or spiciform; glumes membranous Imperata
43a. Inflorescence axillary Pogonatherum
43b. Inflorescence terminal Eulalia
44a. Inflorescence a panicle with elongated central axis; raceme internodes never with a translucent median line 45
44b. Inflorescence of single or subdigitate racemes, sometimes with an elongated central axis but then raceme internodes with a translucent median line 47
45a. Lower glume of sessile spikelet dorsally compressed Sorghum
45b. Lower glume of sessile spikelet laterally compressed 46
46a. Raceme composed of several to many spikelet pairs; awns slender or inconspicuous Vetiveria
46b. Raceme reduced to a triad; awns usually prominent Chrysopogon
47a. Pedicels and internodes with a translucent median line 48
47b. Pedicels and internodes without a translucent median line 49
48a. Inflorescence a panicle; racemes of 1-5 (-8) sessile spikelets Capillipedium
48b. Inflorescence of single or subdigitate racemes, rarely paniculate and then racemes bearing more than 8 sessile spikelets Bothriochloa
49a Lower floret of sessile spikelet male, with a palea 50
49b. Lower floret of sessile spikelet barren and reduced to a lemma 51
50a. Sessile spikelet dorsally compressed; racemes usually 2 or more Ischaemum
50b. Sessile spikelet laterally compressed; racemes single, spathate Apluda