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Eucalyptus spp.
eucalyptus
Australia (700+ species); a few species native to Southeast Asia and nearby islandsLearn more
Overview
Eucalyptus is a genus of 700+ species of evergreen trees and shrubs in the myrtle family (Myrtaceae), native to Australia. Size ranges from multi-stemmed mallees 180 inches (450 cm) to the tallest flowering plant on Earth — E. regnans (mountain ash) at 3,600 inches (9,000 cm / 300 feet). Peeling bark in species-specific patterns: smooth (revealing green, cream, orange, or gray new bark), fibrous, stringy, or tessellated. Juvenile and adult leaf forms differ (heterophylly): juvenile leaves are often rounded and blue-gray (glaucous); adult leaves are lance-shaped, dark green, and leathery. All foliage contains eucalyptol (cineole), a volatile aromatic oil. Flowers have no petals — the bud is covered by a cap (operculum) that falls off to expose a cluster of stamens in white, cream, pink, red, or yellow. The genus name means 'well-covered' (Greek eu + kalyptos) — referencing the operculum. Fire-adapted: epicormic buds beneath the bark resprout after fire; the volatile leaf oils increase fire intensity. Allelopathic: leaf litter inhibits seed germination of other species beneath the canopy. Brittle branch drop — large branches fall without warning in calm conditions (a safety concern in public spaces). Species cultivated in the Pacific Northwest: E. gunnii (cider gum — hardiest, zone 7), E. pauciflora subsp. niphophila (snow gum — zone 7), E. globulus (blue gum — zone 8). Eucalyptol oil is toxic to dogs and cats. Deer-resistant. Full sun. Zones 7–10 (varies by species). This entry represents the genus. Growth rate is fast to very fast.
Native Range
Native to Australia (700+ species). A few species are native to Southeast Asia (Indonesia, Philippines, Papua New Guinea). Widely planted worldwide as timber, pulpwood, and amenity trees.Suggested Uses
Grown as specimens and windbreaks in zones 7–10 (species-dependent). Coppiced for juvenile foliage (floral industry). Fire risk in dry climates. Brittle branch drop (avoid high-traffic areas). Eucalyptol toxic to pets. Deer-resistant.How to Identify
Appearance
Size & Dimensions
Height15' - 300'
Width/Spread10' - 100'
Reaches mature size in approximately 10 years
Bloom Information
Varies by species — winter, spring, or summer. Fluffy stamen-cluster flowers (no petals). The operculum (bud cap) falls off to expose the stamen clusters. Nectar source for bees (eucalyptus honey).Detailed Descriptions
Flower Description
White, cream, pink, red, or yellow; fluffy stamen clusters (no petals); the bud cap (operculum) falls off to expose the stamensFoliage Description
Juvenile leaves often rounded and blue-gray (glaucous); adult leaves lance-shaped, dark green, leathery, aromatic (eucalyptol/cineole oil)Growing Conditions
Sun Requirements
Requires 6-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight