An aquatic plant found along pond margins, cobble shorelines of large rivers, tidal mudflats, and shallow gravelly areas of lakes (New York Natural Heritage Program 2004). Infrequent in shallow water and shores of slow-moving rivers and streams and intertidal mud flats (Rhoads and Block 2000). Margins of lakes, ponds, and streams; tidal shores and estuaries; calcareous to slighly acidic substrates in fresh, usually oligotrophic, water (Flora of North America 1993). Gravelly or muddy, tidal or non-tidal, fresh-water shores. In ponds, streams, and fresh or slightly brackish rivers, rooted in gravel or mud (Gleason and Cronquist 1991). Fresh or tidal shores and shallow water (Fernald 1970).

Brackish intertidal mudflats A sparsely vegetated community, characterized by low-growing, rosette-leaved aquatics. The community occurs on exposed intertidal mudflats where water salinity ranges from 0.5 to 18.0 ppt. This community is best developed where mudflats are nearly level so that broad expanses are exposed at low tide. The rosette-leaved aquatics are completely submerged at high tide, and they are usually coated with mud. Cobble shore wet meadow A community that occurs on the cobble shores of lakes and streams where the substrate is moist from seepage or intermittent flooding. These communities are likely to be scoured by floods or winter ice floes, but there is apparently no significant accumulation of pack ice. Freshwater intertidal mudflats A sparsely vegetated community characterized by low rosette-leaved aquatics. This community occurs on exposed intertidal mudflats where the water is fresh (salinity less than 0.5 ppt). This community is best developed where mudflats are nearly level so that broad expanses are exposed at low tide. The plants are completely submerged in 0.9 to 1.2 m (3 to 4 ft) of water at high tide and they are usually coated with mud. Inland calcareous lake shore The gravelly, sandy, or muddy shore of an inland lake or pond with calcareous water and seasonally fluctuating water levels. There may be few plants and those that are present are usually herbaceous.

Oligotrophic dimictic lake* The aquatic community of a nutrient-poor lake that typically occurs in a deep, steeply-banked basin. These lakes are dimictic: they have two periods of mixing or turnover (spring and fall), they are thermally stratified in the summer, and they freeze over and become inversely stratified in the winter. * probable association but not confirmed Oligotrophic pond* The aquatic community of a small, shallow, nutrient-poor pond. The water is very clear, and the bottom is usually sandy or rocky. * probable association but not confirmed Unconfined river The aquatic community of large, quiet, base level sections of streams with a very low gradient.

Common Hornwort (Ceratophyllum demersum) Nuttall's Waterweed (Elodea nuttallii) Seven-angle Pipewort (Eriocaulon aquaticum)

Common Water-willow (Justicia americana) Hornleaf Riverweed (Podostemum ceratophyllum) Northern Arrowhead (Sagittaria cuneata)