Carex Lacustris, or Lake Bank Sedge, is one of the largest of the sedges (Carex spp.). The height ranges from 2 ½ feet and 4 feet tall. The stem, or culm, of the plant, is a medium shade of green, pale in color, and has a triangular shape that supports multiple leaves. The dark green leaves can be up to 3 feet in length, often exceeding the length of the culm. The shorter leaves have an upright habit while longer blades present an arched form. The leaves have a deep V in the center and a bend at the margin, creating a flattened M-shape. In addition to supporting multiple blades, each culm also supports numerous spikelets. The spikelets are cylindrical and approximately 2 inches long. On average, there are 2-4 female spikelets and 2-5 male spikelets per culm. Each spikelet is densely packed flower cluster. After the late spring to early summer blooming period, the brown florets cross-pollinate by the wind. Once fertilized, the florets fall from the spikelet and are dispersed to new locations through the water.
It is native to southern Canada and northern United States, USDA Hardiness Zones 5-7. The habitats include marshes, bogs, or shallow depressions in floodplains with highly saturated soil, borders of ponds and small lakes with a few inches of water, and even in shallow water up to 12 inches. Carex Lacustris prefers full sun and wet soil conditions. This adaptable plant also tolerates seasonal flooding. The prime soil conditions contain mud or silt. The Lake Sedge spreads via rhizomes or waterborne seed dispersal. A culm that does not receive enough sun may not produce fertile spikelets. Under the right conditions, Carex Lacustris can form large clonal colonies, useful to impede the erosion of banks along ponds, hence the common name, Lake Bank Sedge.