Hello. In Australia, the watsonia (a declared weed) has been spread by graders (earthmovers) when they grade the gravel roads. Perhaps this is how weeds travel so far, people making new roads, or making gravel roads nice and flat. In Australia, you will see the watsonia all along the side of the roads. It would be nice if the main roads department could try and eradicate it, but it seems to be left up to everybody else. cheers Angela