1 Perennial, with scaly rhizomes; inflorescence either obviously paniculate, 7-25 cm long, with ascending to appressed branches, the main branches of the inflorescence apparent, the inflorescence outline thus appearing lobed, or densely spikelike, 1.5-15 cm long.

..2 Glumes broadly winged; fertile lemmas ovate-lanceolate, densely pubescent; [section Bulbophalaris]

..2 Glumes not winged; fertile lemmas narrowly lanceolate, glabrous to sparsely pubescent; [section Phalaroides]

1 Annual, without rhizomes; inflorescence densely spikelike or almost capitate, 1-9 cm long, the branches not apparent, the inflorescence outline a single ovoid, ellipsoid, or lanceolate form.

....3 Spikelets borne in clusters, the lower 4-7 spikelets in each cluster with a staminate terminal floret; [section Heterachne]

....3 Spikelets borne singly; all spikelets with a bisexual terminal floret.

......4 Keels of the glume narrowly winged (the wing < 0.5 mm wide); sterile florets 0.5-2.5 mm long.

........5 Sterile floret 1; [section Bulbophalaris]

........5 Sterile florets 2; [section Caroliniana].

..........6 Nerves of the glumes scabrous; panicle cylindric in outline, 6-18 cm long; glumes 3.5-4.0 mm long; sterile florets 0.5-1.5 mm long

..........6 Nerves of the glumes not scabrous; panicle narrowly ovate in outline, usually 2-6 cm long; glumes 5-6 mm long; sterile florets 1.5-2.5 mm long