within these regions it has spread, most dramatically and noticeably in central australia after floods of 1974 along the finke river in the northern territory. since then it has become a serious weed and invasive species in the northern territory and western australia. the species had been present for many decades without much spread before this. it tends to use more water than most native plants in australia, which it outcompetes. it has replaced the indigenous eucalyptus along watercourses in the interior. it has been declared a weed of national significance in australia.