Hydrocharitaceae is a plant family that includes a number of species of aquatic plant, broadly called the Tape-grasses, and includes the well known Canadian Waterweed and Frog's Bit. The family includes both fresh and marine aquatics. They are found throughout the world in a wide variety of habitats, but are primarily tropical. The species are annual or perennial, with a creeping monopdial rhizome with the leaves arranged in two vertical rows, or an erect main shoot with roots at the base and s… (More on Hydrocharitaceae)