The Estolide Fraction Of The Leaf Wax Of The If Genus Pinus And Its Use As A Taxonomic Guide

Abstract

Plants have been classified by the botanist according to their morphological and anatomical features. Other characteristics are increasingly supplementing the taxonomic data used by the botanist. One of these characteristics is the chemical content of plants. Its importance as a taxonomic guide derives partly from the fact that chemical constituents have certain advantages over other plant characteristics. Moreover, th data which is increasingly becoming available would appear to indicate that an ideal natural classification of plants is both desirable and possible. Advances in techniques have enabled he phytochemist to make a significant contribution in this direction. Analyses of secondary products have discerned phylogenotic relationships among plants; and the chemotaxonom1st h s been able usefully to add, to the criteria hitherto used by the botanist. The three main botanical classifications of the genus Pinus manifest several differences. wax being a secondary product which has been proved to be taxonomically useful, the present study was undertaken to analyse the chemical constituents of the leaf wax of the thirty Pinus species available locally with a view to determining their taxonomic value. pinus leaf wax contains mainly the estolide (ester) fraction. This fraction is made up almost entirely of (a-hydroxy acids, which are mainly of chain lengths c12' c14 and C16 These acids are present in the estolide fraction of the leaf wax of each species in different proportions. The acid patterns are species specific; and no seasonal variation occurs, though considerable age variation exists as regards wax extracted from young leaves, on the one hand, and dead leaves, on the other. The results , obtained can usefully be discussed in relation to the three main botanical classifications, especially as regards certain varieties being latterly regarded as distinct species. A phylogenetic relationship is discernible in the acid patterns of the species studied which bears a close resemblance to Shaw's phylogenetic classification of this genus. The taxonomist should find this data useful.