Beautiful Eucalyptus Deglupta - Rainbow Gum - Rare Exotic Tropical Tree Bonsai Seeds (50) It's easy to see why this fabulous tree is called the rainbow eucalyptus or rainbow gum. The bark is obviously its most distinctive feature. The bark of the tree begins with one rainbow of colors and, as the tree matures, produces a different vibrant rainbow. Cherished for its ornamental distinction, its wood is also valued for making pulp.