Looking for a bright spot after the monotone winter months? Then set your color-starved eyes on the rainbow eucalyptus. These wild trees might look like a conceptual art installation, but those vibrant hues are all nature made. The only eucalyptus variety native to the northern hemisphere, these trees are cultivated around the world as crowd-pleasing arboretum bait as well as for wood pulp used in paper making. The color of the bark is actually an indication of age. The youngest bark is bright green and matures through a color wheel of purples, oranges, and maroons. And while they look whimsical, they're serious trees. The rainbow eucalyptus can grow to be 240 feet tall and nearly 8 feet in diameter