Gum trees are the most wonderfully evolved species to suit our climate. From the swamp gums which like to have wet feet, to gums that survive in some of the driest of our land, to gums that can withstand intense bush fires and recover. They form hollows in the trunks where branches break off to provide nesting sites for birds and animals, but only when they become quite old. Note politicians, stop the felling old growth native forests.
I could talk about how they breed and grow, but instead I will point out something about their leaves and bark, which are just so well designed.
Now here is a small gum tree branch with the leaves. The first thing to note is how they all hang down. If they were more conventional when rain hits them much of the water would bounce off and some stay on the leaf to quickly evaporate. But with the leaves pointing down and being the shape they are, every drop of precious moisture from rain or even dew is directed straight down to the ground to be taken up by the tree's roots, so necessary for their survival on the driest continent on earth.
The gum trees must also be able to survive fire and generally they can. Only the hottest bush fires seem to kill them. How do they survive?
Many gum trees have a thick fibrous bark and some have smooth bark that peels off in long sections and just hangs. Along comes the fire and the hairy bark quickly takes the fire up to the top of the tree as does the long pieces of very dry hanging bark of the smooth barked gum. Once the fire reaches the leaves, rich in eucalyptus oil and giving off strong fumes, they quickly burn and because of their long and hanging shape, the fire quickly reaches the top of the tree and away from the trunk of the tree. The end result is a tree with no leaves and burnt branches, but the trunk of the tree has been protected. From the trunk, new growth will quickly appear. Note, in the Australian state of New South Wales not far from Sydney are the well known Blue Mountains, so called because of the blue haze that hangs over them, which is eucalyptus fumes from the trees.
Photo from helsieshappenings of a Eucalypt with a thick and protective fibrous bark.
Photo from Clareges.blogspot.com of a smooth barked Eucaplypt with long tendrils of dry bark shed at the right time of the year for bushfires.