1. Spikelets > 4 mm long…S. floridanus (S. curtisii likewise with long spikelet but leaf blades 2 mm wide vs. wider)

1. Spikelets < 3.9 mm long…2

2. Beach species strictly. Leaves strongly distichous in a herringbone pattern. Racemes 1 cm wide, white…S. virginicus (Adaxial surface of leaf blades with dimorphic papillae)

2. Inland species or occasionally maritime; leaves not in a herringbone pattern. Racemes usually broader than 1 cm, usually not tightly congested…3

3. Leaf blades 0.8-1(2) mm wide. Spikelets 2.6-3.8 mm long…S. junceus (spikelets often purplish red. Upper glume equal to the floret. S. curtisii, probably not in area has even larger spikelets)

3. Leaf blades usually > 2 mm wide (S. indicus may be as narrow as 1 mm). Spikelets < 2.5 mm long…4

4. Both glumes much shorter than spikelet. Upper glume ½-2/3 the spikelet length. Spikelet 2-2.5 mm long…S. indicus

4. Upper glume 2/3-almost as long as spikelet. Spikelet 1.6-2 mm long…S. domingensis (panicles thick and full, very dense; leaf blades to 8 mm wide)