Salviniaceae (/sælˌvɪniˈeɪsiˌiː/),[1][2] is a family of heterosporousferns in the order Salviniales.[3] The Salviniaceae contain the two genera Azolla and Salvinia,[4] with about 20 known species in total.[5] The oldest records of the family date to the Late Cretaceous.[6]Azolla was previously placed in its own family, Azollaceae, but research has shown Azolla and Salvinia to be sister genera with the likely phylogenic relationship shown in the following diagram.[7]