ALKANES OF FOLIAR EPICUTICULAR WAXES FROM 5 CYCAD GENERA IN THE ZAMIACEAE

The n-alkane distribution patterns from 31 specimens in the meso-American cycad genera Ceratozamia, Dioon, Zamia and two Australian taxa, reported from GC analysis, complement a previously published investigation of the African genus, Encephalartos and complete a survey of the Zamiaceae. The significant proportions of n-alkane homologues with short (< n-C25) carbon chains, the extended distribution range (n-C26 to n-C33) and a general absence of prevalence of odd- over even-numbered homologues collectively provides evidence for a monophyletic origin of the Zamiaceae and distinguishes the cycads chemotaxonomically from other gymnosperms and from angiosperms. Exceptions to the general trend are seen in Dioon califanoi, which shows an angiosperm-like bias towards odd-numbered carbon alkanes, and to a lesser extent in two species of Ceratozamia and three of Zamia. Alkane distribution profiles do not allow any distinction between the genera of the Zamiaceae and show little species specificity.