The lemon scented Tea Tree, Leptospermum petersonii Bailey is known to exist in at least five chemical varieties. The principal variety contains the monoterpene aldehydes neral, geranial and citronellal as the main components of its leaf essential oil. These three compounds can account for over 80% of the oil.

We have examined the leaf essential oil of the progeny of a single plant of the aldehyde form of L. petersonii. The leaf oil from the cotyledons contained none of the above three aldehydes. Instead, it contained a series of macrocyclic sesquiterpene hydrocarbons of the germacrene and bicyclogermacrene series as well as their thermal decomposition products.

The seedling leaf oil also contained the same oil as the cotyledons. It was not until the seedling had reached a height of approximately 15cm and had a large number of well developed leaves that the presence of neral, geranial and citronellal was observed in individual leaves towards the base of the seedling, while further up the seedling the leaves contained the sesquiterpene hydrocarbons and none of the monoterpenes.

Evidence for these findings will be presented.