Eucalyptus

Eucalyptus is a vast genus of more than 700 species of flowering trees and shrubs, almost all native to Australia. They are among the fastest-growing trees on Earth, and several species dominate the landscape in their homeland and in plantations worldwide.

The foliage is intensely aromatic thanks to volatile oils, and the leaves famously change shape with age — rounded and silvery on young growth, longer and sickle-shaped on mature stems. The bark often peels in ribbons or patches, revealing smooth, multi-colored trunks.

Widely grown for timber, pulp, essential oil, and as an ornamental, eucalyptus is also used in florists' cut foliage. Young plants and cut sprigs are popular indoors and in arrangements.

• Leaves: Juvenile leaves are rounded, blue-grey and clasp the stem in pairs; adult leaves are long, narrow, leathery and sickle-shaped, hanging downward
• Aroma: Crushed leaves release a strong menthol-camphor scent
• Bark: Smooth and peeling in many species, shedding in ribbons or flakes to reveal pale, mottled trunks
• Flowers: Fluffy, stamen-rich blooms (white, cream, yellow, pink or red) with no petals; capped buds give the genus its name (Greek eu-kalyptos, "well covered")
• Fruit: Woody, cup- or bell-shaped capsules ("gum nuts")
• Size: Highly variable; E. globulus can exceed 45 m (150 ft) in the wild

Light: Full sun is essential; eucalyptus will not thrive in shade.

Water: Drought-tolerant once established, but water deeply during the first year or two. Avoid waterlogged soil.

Soil: Well-draining soil; tolerates poor and sandy ground. Dislikes heavy, soggy clay.

Temperature: Hardiness varies widely by species; E. globulus is tender to hard frost, while species like E. gunnii and E. pauciflora tolerate cold.

Feeding: Generally not needed; eucalyptus is adapted to nutrient-poor soils and can suffer from excess fertilizer.

Propagation: Usually grown from seed (some species need a cold-stratification period); fast-growing seedlings establish quickly. Can be coppiced for juvenile foliage.

Eucalyptus is native to Australia, with a handful of species reaching into New Guinea, Indonesia and the Philippines. It occupies habitats from coastal forests to arid interior and alpine snow gum country.

Because of its fast growth, the genus has been planted across the world — in Mediterranean climates, California, South America, Africa, India and southern Europe — for timber, pulp, oil and windbreaks. In some regions it has become invasive and is criticized for being highly flammable and draining groundwater.

• Timber and pulp: A major source of hardwood and paper pulp worldwide
• Essential oil: Steam-distilled leaf oil is used in decongestants, rubs, cleaning products and aromatherapy
• Ornamental and floristry: Silvery juvenile foliage is a staple of cut-flower arrangements and dried bouquets
• Ecological: Provides nectar for bees (eucalyptus honey) and habitat for wildlife such as koalas, which feed almost exclusively on eucalyptus leaves
• Practical: Planted as fast-growing windbreaks and for erosion control, though caution is needed due to fire risk