Essential Oils from the Leaves of the Australian Species of Palmeria (Monimiaceae)

Journal of Essential Oil Research: JEOR, Jul/Aug 2004 by Brophy, Joseph J, Goldsack, Robert J, Forster, Paul I

Abstract

The leaf oils of the Australian species of Palmeria (Monimaceae) were subjected to analysis by GC and GC/MS. From the results obtained it could be seen that the Palmeria species can be divided into four groups depending on the major components present in their leaf oils, viz. elemol, spathulenol, bicyclogermacrene and ishwarane. Only in one case, those samples from Mt Bellenden Ker, where elemol was the major component, was the oil composition linked to a specific locality.

Key Word Index

Palmeria hypotephra, Palmeria scandens, Monimiaceae, essential oil composition, camphene, [beta]-pinene, bicyclogermacrene, spathulenol, ishwarane, elemol.

Introduction

The genus Palmeria F. Muell. is comprised of around 15 species of scandent climbers and is distributed from Sulawesi through New Guinea into eastern Australia (1). It is the only genus of the tribe Palmerieae in the subfamily Monimioideae in abroadly circumscribed Monimiaceae (2,3). Palmeria is considered to be phylogenetically basal in Monimiaceae in recent analyses based on moqJiological and molecular data sets (4,5). The species of Palmeria are the only climbers in the Monimiaceae (3). Twelve species of Palmera were enumerated for New Guinea and Sulawesi, with a further three indicated for Australia (1).

The systematics of the Australian Palmeria species is fraught with difficulty and it is unclear as to how many taxa are present. Bentham (6) recognised two species (P. racemosa (TuI.) A.DC. and Palmeria scandens F. Muell.) and distinguished them primarily on the number of stamens in the male flowers. Palmeria scandons is based on a type collection from north Queensland (Rockingham Bay) whereas that for P. racemosa is unclear (cited as 'Nova Hollandia'), although Bentham (6) speculated that it was "probably from Moreton Bay, or from the northern districts of N.S. Wales." Woolls in 1882 considered that intermediates could be found for this character state and concluded that only one widespread species was present in the whole of eastern Australia (7). Additional species were added by Domin (8) with P. hypotephra (F. Muell.) Domin (type collection from the summit of Mt Bellenden-Ker in north Queensland) and by White (9) with P. coriacea C.T. White (type collection from Thorn ton Peak in north Queensland). Only two species (P. scandens and P. hypotephra) have been recognized for Queensland in recent times (10,11); however, this was not based on any rigorous systematic study. A single species (JR scandens) is recognized for New South Wales (12). In an as yet unpublished account of Monimiaceae for the 'Flora of Australia,' Foreman and Whiffin (13) concluded that three species are present in eastern Australia, namely P. scandens throughout the distributional range, P. hypotephra in northeast Queensland and an as yet unnamed species from southern Queensland and northeastern New South Wales. These authors included P. coriacea in the synonymy of P. scandens, but did not adequately resolve the status of P racemosa. The three species that they recognized were distinguished by perceived differences in the foliage indumentum color and the composition of the indumentum.

Plants of Palmeria are extremely variable in leaf morphological expression, depending on the degree of exposure (e.g. strong sun or wind versus deep shade). Both P hypotephra and P coriacea were based on type collections from the tops of high mountains (1,300-1,550 m) where the plants often occur in exposed and windswept conditions. In these situations the foliage is comprised of small, thick leaves with a dense indumentum. Similar foliage can also be encountered on sun-leaves in lowland situations. When plants are encountered in sheltered, shaded conditions (irrespective of altitude), the foliage is much lusher, with leaves that are larger, thinner and with more scattered indumentum. It is not unusual to encounter individual plants where it is possible to physically connect the two types of foliage, with sun-leaves at the top of the canopy and shade-leaves in the understorey. The distribution oi Palmeria in eastern Australia is disjunct with two main areas of distribution, northern Queensland from the Mcllwraith Range in the north to Eungella in the south, and southern Queensland to southern New South Wales from Kin Kin in the north to the Illawarra in the south. From field experience of one of us (PIF) it is concluded that either (1) a single very variable species occurs throughout the entire range, or (2) two or more species occur, separated in the two geographic areas of distribution, or separated ecologically.

The aim of this paper is to document the compositional variations of the essential oils in the Australian populations of Palmeria and to ascertain whether any discernible patterns can be seen that can be related to the cited variables of sun or shade, geographical distribution or altitude. As a consequence, an attempt has been made to sample material from known or proposed type localities and throughout the Australian distributional and ecological range. Although we have not been able to sample material from the type locality of P. corincea, we did obtain samples from the nearby Mt Finnigan. Although there have been previous studies of the alkaloids found in Australia Palmeria (14,15), there are no studies on the essential oils of any species.