Myriophyllum variifolium is a species of water milfoil native to eastern Australia where it grows in aquatic habitat such as ponds and streams. Joseph Dalton Hooker described the species in 1840, from material collected in the Lachlan River, as well as Tasmania. The Tasmanian material resembled the description more closely, and the New South Wales material has been separated as a different species, hence the original Tasmanian material was made the neolectotype.