It is topped with a grayish, buttonlike inflorescence just a few millimeters wide.

[4] This plant grows in coastal habitat types, such as mudflats, estuaries, and marshes, but in freshwater or slightly brackish water.

The substrate is often subject to scouring from water action, including tides and floods.

This species is associated with other plants such as Zizania aquatica, Ludwigia palustris, Isoetes riparia, Schoenoplectus pungens, Bidens eatonii, Bidens hyperborea, Polygonum punctatum, Lindernia dubia var.

inundata, Elatine minima, Elatine americana, Sagittaria subulata, Sagittaria latifolia, Sagittaria calycina, Acorus calamus, Limosella australis, Micranthemum micranthemoides, Pontederia cordata, Orontium aquaticum, and, in more brackish waters, Spartina alterniflora.