Fens, calcareous sedge meadows, openings in cedar swamps, calcareous shores and seeps; particularly characteristic of sandy-marly flats and interdunal swales along the northern shores of Lakes Michigan and Huron.

This can be a major dominant of calcareous shores, and most especially fens, where it occurs in dense clumps; these forming small hummocks similar to those of Carex stricta, but much lower.

Though the plant is basically dioecious, the inflorescences can be somewhat variable. Largely male plants, with few or even no perigynia in the spikes, and largely female plants, with few or no male flowers, look quite different. Though baffling at first, once one is familiar with the species, this odd feature makes it easy to recognize.