Setaria magna Griseb.
Giant Bristlegrass
Natural range: U.S. to Mesoamerica
Habitat: Mostly saline or brackish marshes or swamps, also in apparent freshwater swamps
Florida status: Native.
Recognition: Huge grass, the stem potentially multiple cm in diameter. Panicle to 50 cm. Spikelets 2 mm long. Upper lemma smooth (other Setarias with rugose upper lemmas).