The Bottomland hardwood forest is a type of deciduous and evergreen hardwood forest found in US broad lowland floodplains along large rivers and lakes. They are occasionally flooded, which builds up the alluvial soils required for the gum, oak and bald cypress trees that typically grow in this type of biome. The trees often develop unique characteristics to allow submergence, including cypress knees and fluted trunks, but can not survive continuous flooding.