By Joseph J. Brophy, Robert J. Goldsack, Lyn A. Craven and Andrew J. Ford

Abstract: Abstract: The leaf oil of the newly described species, Backhousia enata A.J. Ford, Craven et J. Holmes was analyzed by a combination of GC and GC/MS. It has been found to contain α-pinene (14–17%) and β-pinene (36–42%) as principal components. The oil yield was 0.3–0.7% w/w based on dry leaf. Key Word Index: Backhousia enata, Backhousia oligantha, Backhousia anisata, Backhousia sp., Anetholea anisata, Syzygium anisatum, Myrtaceae, essential oil composition, α-pinene, β-pinene.

Introduction
Backhousia enata A.J. Ford, Craven et J. Holmes is a recently described species (1) that occurs in northeastern Queensland, Australia, where it is endemic to the ‘Wet Tropics’ and is currently confined to the Tully River catchment area to the northwest of Tully, Queensland. It inhabits notophyll vine forest/rainforest on soil derived from rhyolite and basalt. At present there are less than 200 individuals known.

Backhousia enata is a large shrub or tree growing to 5–15 m in height, with a trunk diameter of up to 20 cm dbh, usually with numerous coppice shoots. It has opposite, laminate, ovate to elliptic-obovate leaves, 24–38 x 11–18 mm in size, with moderately dense oil glands that are conspicuous on both sides. Morphologically, B. enata is most closely related to B. myrtifolia Hook. et Harvey, from which it is geographically separated by approximately 1,000 kilometres. Full morphological details are given in (1).

The leaf oils of all the Backhousia Hook. et Harvey species known up to July 1994 have been investigated (2 and references therein). Since then, the species known as Backhousia sp. (Didcot P.I.Forster 12671) (in 2) has been formally named as B. oligantha Bean (3). Moreover, on the basis of DNA, morphological and anatomical studies, B. anisata has been renamed Anetholea anisata Peter G. Wilson (4). Craven and Biffin, however, considered that the distinction between Anetholea Peter G. Wilson and Syzygium Gaertn. was slight and have now transferred this species to Syzygium under the name Syzygium anisatum (Vickery) Craven et Biffin (5). In this short communication, we describe the composition of the leaf oil of B. enata and compare it with that of other members of the broader genus Backhousia.