Hydatellaceae are a small and ancient family of aquatic herbs
containing a single genus, Trithuria (although some species
were previously recognised as a different genus, Hydatella).
Although they were traditionally placed among the monocots because
they superficially resemble tiny grasses or sedges, they are in fact
related to the water lilies.
Tasmania has one species of each of
the two genera in this family. Both are tiny aquatic/subaquatic