Australian Outback boasts that it is "the worlds most extensive Eucalyptus browse plantation," providing North American zoos with leaves for captive koalas, which feed almost exclusively on Eucalyptus. There are seven hundred species in the world, and all but fifteen are native only to Australia. Here in Phoenix, around forty species are available through the garden trade. gum trees are revered for their beauty, shade and as fast-growing trees that provide wind breaks and screening in agricultural and industrial areas. That is why rows of eucalyptus are commonly planted along our roads and freeways and other not-so-scenic parts of the city, which is just about everywhere! Gum trees also make excellent pulpwood; the soft fibers are especially useful for making tissue paper. You probably have rolls or boxes of eucalyptus-based papers in your bathroom! In your medicine cabinet too, you may have throat lozenges, toothpaste or other cosmetics that contain eucalyptus oil.
Although it would be difficult to support a population of koalas in Phoenix gum trees, many native birds and insects have adapted to using them for food and shelter. most notably, monarch butterflies will roost and feed on Eucalypts during their annual migration. This is especially prevalent along the coast of California, where hundreds of thousands of monarchs roost during the winter months. In the annals of evolutionary biology, rapid adaptive responses to recently introduced species are a unique crucible for speciation. On the other hand, some people view any non-native species as a pest that interferes with the natural order of things, so many eucalypt forests are targeted for destruction, especially since they are also fire and windfall prone trees.
However, a special Red Gum (E. camaldulensis), affectionately known as "Mr. Big," is well-guarded and cared for not far from Phoenix at the Boyce Thompson Arboretum in Superior. The giant is reputed to be the National Champion of its kind, running neck and neck with a specimen in California at over one hundred forty feet tall and over six feet in diameter. Equally notable is Mr. Big's stats as the State Champion of all trees for height in Arizona, topping the runner-up Ponderosa pine in height by over thirteen feet!