Lemon-scented gum

Lemon-scented gum is an evergreen tree 25–40 m tall (occasionally 50 m) with a straight trunk and smooth, powdery white to pink-grey bark that sheds in flakes. Adult leaves are narrow-lanceolate, 10–20 cm long, releasing a strong lemon scent when crushed because of their high citronellal content. Cream-white flowers are borne in groups of three; the fruit is an urn- to barrel-shaped capsule.

The species originates from coastal and subcoastal open forests of eastern Queensland, Australia, from around Gladstone–Maryborough north to Cooktown. It is now widely planted throughout the tropics and subtropics — Vietnam, China, India, Brazil, South Africa, Israel — for timber, pulp and essential oil.

The wood is pale cream to light brown, fairly heavy and durable, used for structural work, poles, railway sleepers, flooring, outdoor joinery and pulp. Steam-distilling fresh leaves yields a lemony oil used in soaps, perfumes, candles, mosquito-repellent products and cosmetic fragrances.

The oil's main constituent is citronellal (60–85%), accompanied by citronellol, isopulegol, citronellyl acetate and small amounts of 1,8-cineole, limonene and α-pinene. This gives it antimicrobial and insect-repellent properties and makes it an industrial precursor for menthol synthesis via isopulegol.