Kangaroo Island grass tree or Yakka tree. Grass Trees have a lifespan of up to 600 years. are not grasses, nor are they trees. Actually, they are distantly related to lilies. All 28 species of grass tree are native only to Australia. They can recover quickly after a fire thanks to reserves of starch stored in their stem.Grass trees provide food for birds, insects, and mammals, which feast on the nectar, pollen, and seeds. Beetle larvae living within the flower spikes are a delicacy for cockatoos. Invertebrates such as green carpenter bees build nests inside the hollowed out scapes of flowers. S