Ceratophyllales

Hornwort (Ceratophyllum demersum). Found in ponds and slow streams throughout North America, except extreme north. This plant is shallow-rooted, deriving most of its sustenance from the water. Will thrive in cold spring water.

Hornword (Ceratophyllum demersum). Found in ponds and slow streams throughout North America, except extreme north. (After Britton & Brown)