Eucalyptus is a rapidly-growing evergreen native to Australia and Tasmania. It's tall, too. In 1872, a eucalyptus in Victoria, Australia, earned the distinction as the tallest tree on record at 375 feet tall, according to The International Society of Arboriculture Australia Chapter. The leaves range in color from bluish to silvery green and the bark tends to peel. Eucalyptus grows in Africa, America, Asia and Europe, but the leaves and wood serve practical purposes worldwide.
Explorers, buccaneers and botanists introduced eucalyptus to the western world. The Dutch seafarer Abel Janszoon Tasman described tall trees in a journal entry during his 1640 exploration of the island later called Tasmania. In 1688, the plant enthusiast and pirate James Dampier remarked that the trees on New Holland, as Australia was then known, secreted a gum-like substance. Not long after, an affluent botanist, Joseph Banks, traveled with the famed buccaneer Captain Cook to New Holland to collect "gum tree" samples, according to Diana Wells' "The Life of Trees: an Uncommon History."
Eucalyptus figures prominently in the oral history of Australia's native Aboriginal people. Most stories remain part of sacred traditions, and so are rarely shared with the outside world. Fred Hedeneger, author of "The Meaning of Trees: Botany, History, Healing, Lore," says one well-known application of eucalyptus involves the didgeridoo, an instrument used for ceremonial purposes. The didgeridoo is a wind instrument, often described as a drone pipe or natural wood trumpet. Traditionally, a didgeridoo consisted of wood from eucalyptus trees that had been hollowed out by termites.
The pioneers of Australia relied on eucalyptus to produce everything from buildings to furniture. When shipbuilders discovered the tall trunks yielded beams, keels and planks, the trees fueled an economic boom. Robert L. Santos, author of the study "The Eucalyptus of California: Section One-The Early Years," says settlers, who traveled to the American West during the Gold Rush, required timber for fuel and shelter. The Australian ships carried the much needed timber to San Francisco quicker than cargo ships from the eastern United States. The American settlers used the imported timber for construction and firewood and the fast growing seed for landscape plantings.
The University of Maryland Medical Center's "Eucalyptus" page says the leaves contain fever-reducing tannins, inflammation-reducing flavonoids and antiseptic substances. Aboriginal people used the leaves to make an ointment for wounds and fungal infections. Then Chinese, European and Indian (Ayurvedic) medicine began to use eucalyptus as word of its medicinal value spread. Hospitals in England used the oil to sanitize urinary catheters during the 19th century. Today, eucalyptus serves as an ingredient in cough and cold medicine and hygiene products.
Red gum and flooded gum represent the types of eucalyptus that grow in the United States. Both trees need full sun and perform best in arid or semi-arid climates. They tolerate drought but benefit from deep watering. They shed bark, leaves and seed, and so require cleanup. One important difference between the two trees lies in their landscape value. The University of Arizona Pima County Extension says red gum trees grow too large for residential plantings. At a minimum 80-foot height and 50-foot spread, red gum trees are more suited for park settings and reforestation applications. Flooded gum trees possess a maximum 50-foot height and 40-foot spread and work well for residential settings.