Water oak serves the same ecological role as weeping willow and other wetland trees.
Hybrids of water oak are known with southern red oak (Quercus falcata), bluejack oak (Quercus incana), turkey oak (Quercus laevis), blackjack oak (Quercus marilandica), willow oak (Quercus phellos), Shumard oak (Quercus shumardii), and black oak (Quercus velutina) .