Large, fast-growing evergreen trees which grow to considerable heights in warm climates, averaging 70 m (230 ft.), with varying estimates for the record, dating from 1872 between 97 m (318 ft.) and 132.5 m (434 ft.). Many have distinctive, rounded juvenile foliage, adult leaves of E. globulus and E. gunnii are lance late, blue-grey and studded with oil-bearing glands. Clusters of fluffy cream-colored flowers appear in summer, followed by globe-shaped fruits.
History and traditions
Eucalyptus trees are native to Australia and were used by the Aborigines in their traditional medicine. They have been widely adopted by other countries, including Africa, the Americas, India and southern Europe, as timber and shade trees, for planting in marshy ground to dry out malaria-inducing swamps, and for their volatile (essential) oil content. Commercial production of eucalyptus essential oils began in Australia in the second half of the 19th century, coinciding with their introduction to the West by a German botanist and director of the Melbourne Botanical Gardens.
Species
There are over 500 species and all contain antiseptic essential oils, though constituents and properties vary. E. globulus (blue gum) has been most widely cultivated around the world and has attractive, juvenile leaves much sought after in floristry. E. gunnii is one of the hardiest and most suited to growing in cool temperate regions.
Growth
Eucalyptus spp. vary from tender to fully hardy but none will stand prolonged low temperatures, especially when immature, E. globulus is half-hardy, -5°C (23°F), and E. gunnii is frost-hardy, -15°C (5°F). Grow in well-drained soil and full sun. Propagate from seed, sow under cover in spring or autumn.
Uses
Medicinal
Eucalyptus has decongestant, expectorant properties and helps to lower fever. The essential oil is highly antiseptic. Leaf or oil is used in steam inhalations and vapor rubs to ease the symptoms of colds, catarrh, sinusitis and respiratory-tract infections. Essential oil is used in massage oils and compresses for inflammations, rheumatism and painful joints.
