Flat sedge has the typical overall appearance of the genus: few leaves at the plant base; long, leaf-like bracts around the base of the inflorescence; and clusters of narrow, pointed spikelets. Flatsedge grows abundantly along every kind of marshy shore and wet clearing throughout the state. Flatsedge grows from 4 to 30 inches tall. It may have a few leaves rising from the base of the plant, and a few loose sheaths. The leaves are about one-half-inch wide and may be as long as the plant. The base of the inflorescence has 3 to 10 conspicuous leaf-like bracts. The bracts are about one-half-inch wide and can be much longer than the inflorescence. The inflorescence of flat sedge may be very small or quite large: from 1 to 18 inches long. The inflorescence has several small, bottle-brush-like clusters of spikelets. The clusters are on very unequal stalks. Some may be short; and some, long. The spikelets are very narrow and relatively long. They have overlapping scales. This typical umbrella sedge has a few leaves rising from the base of the plant. It has several leaf-like bracts at the base of the inflorescence. Some bracts may be much longer than the inflorescence. It has several small, bottle-brush-like clusters of spikelets. The spikelets are very narrow and relatively long.
For brief control information, see Efficacy of Herbicide Active Ingredients Against Aquatic Weeds by K. Langeland, M. Netherland, and W. Haller.