 The species is almost totally restricted to the swales and lower slopes of dunes . Various reasons for this have been proposed ; on the one hand , it has been argued that its dependence on ground water necessitates that it grow only where ground water is relatively near the surface ; on the other hand , it has been suggested that it cannot survive in higher parts of the landscape because fires are too frequent there . The latter hypothesis is supported by the recent expansion of B. prionotes along road verges of the Brand Highway , where fires are relatively rare . Despite B. prionotes ' occurrence in lower parts of the landscape , it does not occur in areas prone to flooding , because of its intolerance of heavy soils , and because extended periods of flooding kill seedlings . However , recent falls of the water table on the Swan Coastal Plain have seen B. prionotes replace the more water @-@ loving Banksia littoralis in some areas that were previously flood @-@ prone . 
