Potamogetonaceae - the Pondweed Family
Diversity: Fully aquatic, perennial herbs with submersed rhizomes and floating leaves from erect, leafy branches. Three genera with about 90 species.
Distribution: Worldwide and centered in aquatic situations, i.e., not common elements of any flora BUT usually present and conspicuous in ponds, lakes, and rivers. We have two genera (Coleogeton and Potamogeton) and 12 species in the Texas flora with one endangered.
Significant features: Flowers perfect, apocarpous, anemophilous, and reduced - often forming a distinctive, emergent spike. Origin of the 4 tepals is uncertain (perianth vs. stamen appendages). These plants are important food-producers in fresh water habitats. (photo overview from CalPhotos)
image from the Delta family description
More information on the Potamogetonaceae