Keys prepared by Richard W. Pohl† and Kenton L. Chambers for the Manual of Grasses for North America

1 Culms rarely developed in the Manual region; leaves smelling of lemon or citronella when crushed Cymbopogon
1 Culms usually developed in the Manual region, but leaves not smelling of lemon or   citronella when crushed (2)

2(1b) Culms 2 to many meters tall, stiff-stemmed, often woody and lasting several years, from slender to 10 cm thick; blades sometimes pseudopetiolate and developed only on the leaves of the branches; some species rarely blooming  Key 1
2 Culms rarely more than 2 meters tall, stiff or flexible, usually not woody, usually lasting only 1 year; blades rarely pseudopetiolate, usually developed on all leaves; most species blooming annually (except under extreme growing conditions) (3)

3 Blades pseudopetiolate, either with cross-venation or with evidently diverging veins (4)
3   Blades not pseudopetiolate, with parallel venation (5)

4 Culms woody; plants shrubby; blades with evident cross-venation; ornamental species  Shibatea
4 Culms herbaceous, not branched above the base; plants not shrubby; blades with diverging veins; rare native species of Florida Pharus

5(3b) All or most of the seed-forming spikelets hidden in spiny burs, bony rachis internodes, bead-like structures, detachable fascicles of hard bracts, or completely hidden in the sheaths, only the stamens and stigmas visible (in some ‘hidden’ spikelets, 1 glume may be visible) Key 2
5 All or most of the seed-forming (fertile) spikelets exposed (6)

6(5b) Spikelets disarticulating in the rachis or beneath the glumes (in the latter case a minute cupule), or, in a few genera, the spikelets not disarticulating at maturity (7)
6 Spikelets disarticulating above the glumes (which remain attached to the rachis or pedicels), or both glumes apparently absent (the florets disarticulating from a persistent rachilla in some species of Eragrostis and Neeragrostis) (8)

7(6a)   Spikelets falling as single units, without accessory structures Key 3
7 Spikelets falling in groups and/or with accessory structures attached (such as rachis internodes, pedicels, bristle-like sterile branches) or remaining on the plant at maturity  Key 4

8(6b) Spikelets with a single fertile floret and nor rudimentary or sterile florets Key 5
8 Spikelets with 2 to many florets, some of which may be reduced or sterile (9)

9(8b) Inflorescence of 1 to many spikes or spikelike branches, or a raceme with 1 spikelet per node Key 6
9 Inflorescence an open or dense panicle; spikelets peridcellate or subsessile, but not arranged on spikelike branches (if raceme-like, then more than 1 spikelet at some of the lower nodes) Key 7

Natural Key to the Genera
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