Common name: Lemon tea tree

Lemon tea tree is a large shrub or small tree yielding valuable lemon-scented essential oil, for which it is cultivated in Kenya and Guatemala. Curiously, however, it originates from eastern Australia, from a small area in north-east New South Wales and neighbouring south-east Queensland.

It grows either as a shrub 2 to 3 m (7 to 10 ft) tall or a small, low-branching tree up to 5 m (16 ft) and on open sites forms a densely leafy rounded crown. The bark is light brown and fissured, sometimes flaking. Growth is moderate to fast, depending on the growing conditions.

The leaves are sword-shaped, 3 to 4 cm ( 1.2 to 1.6 in ) long, emerge bright bronze-red and remain on the plant throughout the year. When crushed they release a pleasing lemon aroma. 

From spring to summer, small white flowers with erect stamens bloom in large numbers that partly hide the foliage from view. They are followed by woody, cup-shaped seed capsules with valves that open as the capsule matures, releasing their seed.

Use

The leaves and young stems yield, on steam distillation, commercial quantities of a lemon-scented essential oil traded as 'Lemon scented tea tree oil'. It has a high citral and citronellal content, giving it a range of applications. It is used as a lemon flavouring agent in soft drinks and teas, as a fragrance component in perfumery, and due to its high citronellal content, it possesses insect repellent properties.

The quality of its lemon aroma is close to that of Lemon myrtle (Backhousia citriodora). Oil yields range from 1.0 to 1.5% by weight, according to the growing conditions and the proportion of new to old growth in the distilled material. 

It is also cultivated as an ornamental for its shapely form, fragrant foliage and showy flowering and, closely spaced, serves as a windbreak or hedge. Its dense, compact form and small leaves make it popular in bonsai culture.

Climate

Grows naturally in sub-humid to moderately humid subtropical and tropical mid- to high-elevation climates, generally areas with average annual low temperatures of 9 to 16 °C, average annual high temperatures of 19 to 27 °C and annual rainfall of 700 to 2500 mm, punctuated by a dry season lasting 4 months or less.

Growing

New plants are usually started from seed. Performs best on free-draining clay, loam and sand soils of a moderately acid to neutral nature, generally with a pH of 5.5 to 7.5 and on sites with full to partial sun exposure.

Problem features

It produces seed that remain viable for a long time and is listed in at least one reference publication as having escaped cultivation and as a weed of the environment, but there does not appear to be any record of it anywhere as a serious weed.

Books

• Arctander, S. 1960, Perfume and flavor materials of natural origin, Elizabeth, New Jersey

• Cribb, A. B. & Cribb, J. W. 1982, Useful wild plants in Australia, William Collins, Sydney

• Guenther, E. & Althausen, D. 1948 to 1952, The essential oils (6 volumes), Van Nostrand Publishing, New York

• Randall, R. P. 2002, A global compendium of weeds, R.G. and F.J. Richardson Press, Melbourne

• Randall, R. P. 2007, The introduced flora of Australia and its weed status, Cooperative Research Centre for Australian Weed Management, Glen Osmond, South Australia

• Seidemann, J. 2005, World spice plants: economic usage botany taxonomy, Springer-Verlag, Berlin

• Streets, R. J. & Troup, R. S. 1962, Exotic forest trees in the British Commonwealth, Oxford University Press, Oxford, England