Wet meadows, shores, lakes, streams, fens, marshes, and ditches, sometimes in water up to 3 dm deep; predominantly in calcareous habitats.

Variety aquatilis, with purple-black scales and relatively delicate spikes, is apparently represented by scattered collections from the Upper Peninsula only. The common Michigan plant is var. substricta Kük., which is usually taller and coarser with pale reddish brown scales. The significance of this variation is unclear; a  few Lower Peninsula collections from the Great Lakes shorelines have quite dark scales, but are robust.