All banksias have developed proteoid or cluster roots in response to the nutrient poor conditions of Australian soils (particularly lacking in phosphorus). The plant develop masses of fine lateral roots that form a mat-like structure underneath the soil surface, and enable it to extract nutrients as efficiently possible out of the soil. A study of three co-occurring species in banksia woodland in southwestern Australia—"Banksia menziesii", "B. attenuata" and "B. ilicifolia"—found that all three develop fresh roots in September after winter rainfall, and that the bacteria populations associated with the root systems of "B. menziesii" differ from the other two, and that they also change depending on the age of the roots.