Hydatellaceae are small, aquatic flowering plants. The family includes the genus Trithuria, which has been recently re-defined to include the genus Hydatella. The family consists of about a dozen species. These tiny (few cm tall), relatively simple, aquatic plants occur in Australasia and India. The simple leaves are concentrated around a short stem basally. The plants are submerged and emergent aquatic annuals, rooted in the substrate below the water.
