Leptospermum petersonii F.M. Bail.

Common Name(s): Lemon Scented Tea Tree, Citratum

Distribution: NE NSW and Southern Queensland

Description of Plant: Rounded shrub to 4m high by 3m in width. Leaves bright green, narrow-lanceolate to 4cm with a strong lemon or citronella scent (depending on chemotype) In summer white 1.5cm (sometimes pale pink) flowers appear. The species is well known in cultivation as a street tree in mild to warm climates. For oil production plants are cut off approx. 30cm above ground once they reach 1.5m in high (usually within 18mths of planting) to assist with soft regrowth. This technique is called coppicing and is used with many native species to encourage multistem regrowth with minimal deadwood.

Parts Used: Aerial parts (Leaves, small stems)

Major Chemical Constituents:

1918 saw the first report on this oil by Challinor et al. under its previous name of Leptospermum citratum. They describe it as having “a pleasant lemon-scented odour”, not unusual considering the oil was rich in the aldehydes citronellal, neral and geranial. Interest in the antimicrobial potential of this species was shown by Penfold and his co-workers, in 1942 during the Australian Phytochemical Survey. Penfold et al. discovered three physiological forms of L. citratum (as it was then known) with aldehyde (Type), terpinene (Variety “A”) and one with a soft fragrant rose-like scent (Variety “B”). There has been much recent work on this species by Brophy et al. that has supported and added to these earlier findings. The high aldehyde variety (Type) has been grown commercially in parts of Africa and Guatemala in the past. Australian commercial plantations of Lemon Scented Tea Tree are now producing this oil in quantity.

Therapeutic Properties of Constituents: Anti-infectious, anti-viral, antiseptic, expectorant, anti-inflammatory, digestive stimulant.

L. petersonii has been recommended for the treatment of oily skin and acne. It is also being recommended as for use in natural insect repellents, either alone of combined with M. alternifolia (Tea Tree). The oil is stimulating in minute quantities but sedating and calming at normal strength.

Blending: This very lemon scented oil must be used sparingly within any blends, to prevent other components being drowned out by its vibrant scent. For skin use, I like to blend Lemon Scented Tea Tree with a citrus oil in equal parts to ‘quench’ the irritant effect of the aldehydes found in this oil. Lemon Scented Tea Tree also blends well with wood aroma’s such as cypress, sandalwood and rosewood. Lemon Scented Tea Tree can be used to improve the scent of more medicinal essential oils such as M. alternifolia (Tea Tree). As part of a respiratory blend Lemon Scented Tea Tree will help to clear nasal and bronchial catarrh.

Cautions and Contraindications: There is currently no clinical data on skin sensitisation, so normal aldehyde precautions apply to using this oil. From personal testing I would not recommend using this oil neat on delicate tissues as it exhibits typical aldehyde skin irritation (ouch). These effects are quite nicely neutralised by ‘quenching’ with a high monoterpene content oil (d-limonene, alpha-pinene) as noted above.

Hydrosol: A gentle, fresh lemon, slightly green scented clear liquid. The hydrosol has proven to be a great skin cleanser for oil/olive skin types, being moderately astringent with no skin irritant effects. As a throat gargle either neat (for adults) or dilute with some warm water (for children) it leaves your mouth feeling pleasantly fresh and lemony. I have found this to be a good protection against throat infection and colds (my 6 y.o. son loves to gargle with this hydrosol). Feedback from another aromatherapist has revealed that the neat hydrosol discourages ants and other crawling insects when used to wash down benches. I have used a few drops of Lemon Scented Tea Tree oil in floor washing water for the same effect, the fresh lemony aroma being an added bonus. From a pet care point of view, the hydrosol is apparently being used to good effect on working cattle dogs in the treatment of mange type skin problems and to keep flea infestations under control.

Method of Application: Vaporised or in low concentration in blends.

Extraction Method: Steam distillation

Personal experience: My first experience with Lemon Tea Tree was about 2 years ago. Since then I have used this oil either alone or in combination for a variety of conditions including common cold, influenza, poor concentration, space cleansing. The oil is a wonderful air cleanser and antiseptic. Diffused into the atmosphere it has the ability to destroy moulds, fungi, bacteria and probably viruses. The oil is bright clean and a great room deodoriser, similar to Lemon Myrtle. It is also good as an insect repellent.

I regularly diffuse small amounts of this oil, along with other Australian oil in my home office and have not suffered to the usual extent with sinusitis, head colds or influenza this past winter.

The dried herb when burnt as an incense has strong cleansing properties and is useful for aiding in concentration, not to be used for meditation. The dried herb also makes a pleasant, lemony herbal tea and combines well with other herbs to aid against colds and influenza. Some Australian herbalists have used this species for many years for its antimicrobial, anti-infectous properties.