Corymbia citriodora aka Lemonscented Gum

Corymbia citriodora is an evergreen tree in the myrtle family, Myrtaceae. Its common names are lemon-scented gum and citron-scented gum. The same species has an older name, Eucalyptus citriodora. Its native range starts in Queensland. It extends into northeastern New South Wales. The tree grows in warm regions with a marked dry season. People grow it abroad for timber, oil, and garden use.

This tree grows fast, with a straight trunk and spreading branches. Its crown can look sparse rather than dense. The RHS lists garden heights above 39 feet [12 metres]. It lists spreads above 26 feet [8 metres]. Wild trees reach about 98–131 feet [30–40 metres]. Rare trees reach 164 feet [50 metres]. The smooth bark sheds in flakes. It can look cream, grey, or pink. The slender adult leaves are yellow-green. They have a strong lemon scent.

White flowers can form in small groups of three. They may appear at any time of year. The main flush of bloom comes in winter. Bees and other insects pollinate the flowers. The tree forms woody seed capsules. Its scented leaves and pale trunk add value to gardens. People also use the leaves in cut arrangements. Growers harvest leaf oil for perfume and other uses. They also harvest the wood as a useful crop.

Give this tree full sun and shelter from strong winds. It prefers moist soil that drains well. The soil should have an acid to neutral pH. Clay, loam, and sand can all suit it. It tolerates poor, dry soils, though moisture helps it grow well. In Britain, grow it outdoors in mild coastal or frost-free sites. The RHS rates it H3. Use a cool or temperate greenhouse where frost poses a risk. Under glass, give it bright light and good airflow. Use gritty, lime-free compost. Water well in spring and summer, then water less in winter.

Prune greenhouse plants to help limit growth and promote young leaves. Pests may include eucalyptus gall wasp and eucalyptus sucker. Silver leaf and oedema can also occur. You can scrape a sweet deposit called manna from leaves and eat it. This limited food use does not make the oil safe. PFAF reports that swallowing eucalyptus oil has caused severe poisoning. It also records the plant's use in folk medicine. It notes that leaf oil acts against bacteria.