Banksia seminuda, commonly known as the river banksia, is a tree in the plant genus Banksia. It is found in south west Western Australia from Dwellingup (32°42′ S) to the Broke Inlet east of Denmark (34°57′ S). It is often mistaken for, and was originally considered a subspecies of, the Banksia littoralis. Stephen Hopper described the subspecies remanens as a short-leaved shrubby form found in the coastal sands below granite outcrops in the Walpole-Nornalup National Park, however George does not feel this form warrants taxonomic recognition as it lies within the normal variability of the species and there was no clear distinction between it and the other populations of B. seminuda.

Banksia is a genus of around 170 species of flowering plants in the family Proteaceae. These Australian wildflowers and popular garden plants are easily recognised by their characteristic flower spikes, and woody fruiting "cones" and heads. Banksias range in size from prostrate woody shrubs to trees up to 30 metres (100 ft) tall. They are found in a wide variety of landscapes: sclerophyll forest, (occasionally) rainforest, shrubland, and some more arid landscapes, though not in Australia's deserts.