1	"Pedicellate spikelets usually well-developed, (3.5)6-12 mm long, usually staminate; sessile spikelets 5-12 mm long"	2
1	"Pedicellate spikelets usually vestigial or absent, those of the terminal spikelet units occasionally well-developed and staminate; sessile spikelets 2.6-8.4 mm long"	3
2	"Sessile spikelets with awns 8-25 mm long; ligules 0.4-2.5 mm long; hairs of the rame internodes 2.2-4.2 mm long, sparse to dense; rhizomes sometimes present, the internodes usually less than 2 cm"	"Andropogon gerardii"
2	"Sessile spikelets unawned or with awns less than 11 mm long; ligules (0.9)2.5-4.5 mm long; hairs of the rame internodes 3.7-6.6 mm long, usually dense; rhizomes always present, the internodes often more than 2 cm long"	"Andropogon hallii"
3	"Peduncles with solitary rames; plants of southern Florida"	"Andropogon gracilis"
3	"Peduncles with (1)2-13 rames; plants of varied distribution, including southern Florida"	4
4	"Rames not or scarcely exserted at maturity; peduncles mostly less than 15 mm long at maturity"	5
4	"Rames sometimes exserted above their subtending sheaths at maturity; 1 or more peduncles more than 15 mm long at maturity"	8
5	"Culms 30-140 (usually about 80) cm tall; blades 0.8-5 (usually about 2.5) mm wide; inflorescence units 2-31 per culm"	"Andropogon gyrans"
5	"Culms 20-250 (usually more than 90) cm tall; blades 1.7-9.5 (usually more than 3) mm wide; inflorescence units 3-600 per culm"	6
6	"Blades pubescent, most hairs appressed; callus hairs 1.5-5 mm long"	"Andropogon longiberbis"
6	"Blades glabrous or with spreading (rarely appressed) hairs; callus hairs 1-3 mm long"	7
7	"Blades 11-52 cm long; sheaths smooth, rarely somewhat scabrous; ligules 0.2-1 mm long; keels of the lower glumes usually smooth below midlength, scabrous distally"	"Andropogon virginicus"
7	"Blades 13-109 cm long; sheaths usually scabrous; ligules 0.6-2.2 mm long; keels of the lower glumes sometimes scabrous below midlength"	"Andropogon glomeratus"
8	"Anthers 3"	9
8	"Anthers 1 (rarely 3)"	10
9	"Sessile spikelets 4.5-8.4 mm long; pedicellate spikelets 1.5-3.6 mm long, sterile; plants common and widespread in the southeastern United States"	"Andropogon ternarius"
9	"Sessile spikelets 3-4 mm long; pedicellate spikelets mostly vestigial or absent, those of the terminal spikelet units well-developed and staminate; in the Flora region, known only from southern Florida"	"Andropogon bicornis"
10	"Peduncles with 2-13 rames"	"Andropogon liebmannii"
10	"Peduncles usually with 2 (infrequently up to 4) rames or (in Andropogon gyrans var. gyrans and Andropogon virginicus var. virginicus), 2-5 (infrequently up to 7) rames"	11
11	"Culms 30-120(140) (usually less than 100) cm tall; blades 0.8-5 (usually less than 3) mm wide; inflorescence units 2-31 per culm"	12
11	"Culms (20)90-310 (usually more than 100) cm tall; blades 1.7-9.5 (usually more than 3) mm wide; inflorescence units 5-210 per culm"	13
12	"Peduncles with 2-5 rames; anthers 0.6-1.7 mm long; sessile spikelets (3)4.1-4.4(5.7) mm long"	"Andropogon gyrans"
12	"Peduncles with 2 rames; anthers 1.2-2 mm long; sessile spikelets (4)4.8-5(5.5) mm long"	"Andropogon tracyi"
13	"Upper portion of the plants open, the branches conspicuously arching"	"Andropogon brachystachyus"
13	"Upper portion of the plants dense, the branches usually straight and erect to ascending"	14
14	"Rame internodes usually densely and uniformly pubescent over their entire length; anthers 1.3-3.5 mm long; sessile spikelets (3.8)4-6.1 mm long"	15
14	"Rame internodes sparsely pubescent basally, more densely pubescent distally; anthers 0.5-1.5 mm long; sessile spikelets 2.6-4(5)"	16
15	"Blades 15-35 cm long, often more or less pubescent; sheaths smooth, very rarely somewhat scabrous; anthers 2-3.5 mm long; inflorescence units 5-45 per culm"	"Andropogon arctatus"
15	"Blades 32-61 cm long, usually glabrous; sheaths often scabrous; anthers 1.3-2 mm long; inflorescence units usually at least 50 (9-210) per culm"	"Andropogon floridanus"
16	"Blades 11-52 cm long; sheaths smooth, rarely somewhat scabrous; ligules 0.2-1 mm long; keels of the lower glumes usually smooth below midlength, scabrous distally"	"Andropogon virginicus"
16	"Blades 13-109 cm long; sheaths usually scabrous, sometimes smooth; ligules 0.6-2.2 mm long; keels of the lower glumes sometimes scabrous below midlength"	"Andropogon glomeratus"