Xanthorrhoea is a genus of flowering plants native to Australia and a member of family Xanthorrhoeaceae, Xanthorrhoea is commonly known as yakka, also spelled yacca and yacka, a name probably from a South Australian Aboriginal language. It is another word for grass tree. I am pretty sure this is a Xanthorrhoea plant. Correct me if this is not. New Zealand is very near to Australia and we have a lot of common plant.