Most Australians know the song “Waltzing Matilda”:  Once a jolly swagman camped by a billabong Under the shade of a coolabah tree …  As that swagman was camped under a coolabah, there is a fair bet he was up along or near the River Darling. Many inland streams had Eucalyptus coolabah growing on their banks—and perhaps there were E. camaldulensis (river red-gums) too, but he would have been wise to the way they drop limbs on hot days. And a coolabah was more pleasant tree to camp under than the other common tree, the black box (E. bicolor). A billabong,…