E. olivacea of Michigan Flora.

Moist sandy to muddy shores, exposed mud flats, bog mats; floating peat mats, often in marly places and sometimes in several cm of water. The styles are occasionally 3-cleft. Our plants are var. olivacea (Torr.) Gleason, with green to golden achenes.

Though detailed observations are lacking, this appears to flower the first year from seed, and may then appear to be a cespitose annual. But it will also send out rizomes and form small mats if the habitat is stable enough to allow the plant to survive for several years.