Biochemical Systematics and Ecology 31 (2003) 339–343 www.elsevier.com/locate/biochemsyseco Comparison of essential oil composition of two varieties of Cistus ladanifer Christine Robles * , Anne Bousquet-Me ´lou, Suzanne Garzino, Gilles Bonin Institut Me ´diterrane ´en d’Ecologie et Pale ´oe ´cologie, UMR 6116, Laboratoire de Biosyste ´matique et Ecologie Me ´diterrane ´enne, Universite ´ de Provence, Case 421 Bis, FST St Je ´ro ˆme, 13397 Marseille Cedex 20, France Received 30 January 2002; accepted 30 May 2002 Keywords: Cistus ladanifer; Cistaceae; Essential oil; Monoterpenes; Sesquiterpenes; Chemotaxonomy 1. Subject and source The species Cistus ladanifer L. (Cistaceae) is a western Mediterranean shrub grow- ing only on siliceous soils (Juhren, 1966). It colonises degraded areas and has an increased distribution as a result of human disturbance (Trabaud, 1995; Luis-Calab- uig et al., 1996). In France, this semi-deciduous shrub grows only in the “Massif de l’Este ´rel” (South of France) forming pure dense stands. Two varieties of Cistus lad- anifer have been described in old local flora: C. ladanifer var. maculatus Dun. and C. ladanifer var. albiflorus Dun. (Rouy and Foucaud, 1895). They present the same vegetative characters. The morphological difference between the two varieties is the presence (C. ladanifer var. maculatus) or the absence (C. ladanifer var. albiflorus) of a red mark on the white corolla. The two varieties are growing mixed in the same areas. Plant material was harvested from three wild sites where the two taxa grow together. The sites are located on siliceous soil in the “Massif de l’Este ´rel” (South of France). In each site and the same day (May 1999 during flowering), young shoots—leaves and stems—were harvested on 20 individuals randomly chosen for * Corresponding author. Tel.: 33-4-91-28-87-19; fax-33-4-91-28-87-07. E-mail address: christine.robles@univ.u-3mrs.fr (C. Robles). 0305-1978/03/$ - see front matter  2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0305-1978(02)00161-8