Jointed flatsedge is occasionally found growing at lake margins, in fresh water and brackish swamps, and marshes from the peninsula west to the central panhandle of Florida. It blooms from summer to fall (Wunderlin, 2003).
Unlike other Cyperus species, this tall native has round and hollow rather than solid stems. It may be mistaken for a species of Scirpus. Look closely at the stem to see nodes and cross-hatching; it is not smooth like bulrush. Birds eat parts of jointed flat sedge. This species of Cyperus is one of around 50 in Florida (Wunderlin, 2003). Jointed flat sedge is located in southeastern U.S., PR, and the Virgin Islands (Kartesz, 1999).
Jointed flat sedge is a sedge. Stems cylindrical, hollow, very tall, to 6 ft. tall, to 3/4 in. wide at base, gradually narrowing, stem cross-hatching at regular node-like intervals; leaf blades none, just purplish basal sheaths; inflorescence of short- and long-stalked spikelet clusters; spikelets narrow, linear, to 2 in. long; nutlet dark brown, 3-angled, shiny.
For brief control information, see Efficacy of Herbicide Active Ingredients Against Aquatic Weeds by K. Langeland, M. Netherland, and W. Haller.