What are some adaptations of the gum tree?

Answer 1

Gum trees, or Eucalyptus trees have numerous adaptations to enable them to thrive in Australia. The trees have poisonous fibrous leaves to limit animals from eating them. Apart from koalas, Greater gliders and Ringtail possums, all of which can eat mature eucalyptus leaves, Australia's native animals can only eat the young shoots of eucalyptus trees.

Gum trees are specially adapted for Australia's bushfire-prone climate. They are known as 'sprouters', which are adult plants that can survive a fire and resprout from the roots or stems. They rely less on seed germination, which is fairly low anyway, than they do on sprouting to ensure continuation of the species. In addition, many eucalyptus species have lignotubers, which are specialised root/crown structures located beneath the soil surface, containing many food-storing cells and shoot-forming structures. Therefore, the lignotubers of eucalyptus trees protet young shoots and provide food for these shoots when they first emerge after a bushfire. Further, also seed germination is low, it is largely reliant on fire to stimulate it. Many types of eucalyptus trees have hard, woody capsules that protect the seeds during fire, but which open after fire, releasing their seeds.

The way gum trees grow is also an adaptation. Many species have wide, spreading canopies which redirect the limited rain that falls down the trunk to concentrate around the roots. The leaves of a eucalyptus tree hang down, rather than horizontally, minimising evaporation and hence water loss (transpiration), as they are not as exposed to sunlight. The leaves usually have equal numbers of stoma on each side, unlike trees which hold their leaves horizontally - they tend to have all or most of their stoma on the lower side. The leaves also tend to have a thick, waxy coating which also minimises water loss.