A survey of epicuticular waxes among genera of Triticeae. I. Ultrastructure of glumes and some leaves as observed with the scanning electron microscope

Abstract

This is the first part of an electron microscopic and chemical study on epicuticular wax. Epicuticular wax ultrastructural morphology (EWUM) of glumes of representatives of 21 genera of Triticeae was determined with the aid of a scanning electron microsope (SEM). Leaves of several genera were examined for specific comparisons to be done later when chemical results are available. This study is based on 120 out of 251 seed accessions obtained from various sources from natural habitats, all grown for the purpose of both SEM and chemical studies in a plot in Ottawa, Canada. Vouchers are preserved and have been critically identified. The results of EWUM demonstrate that the various genera can be characterized by patterns of relative frequencies of the basic wax crystal categories: plates (P), knobs (K), and filaments (F). The variation within each category is also described. Frequencies of P, K, and F have been summarized for each genus. The frequency data have been analysed by principal-coordinate analyses and by Jardine–Sibson Bk cluster analysis to assess and interpret the phenetic relationships between the generic EWUM frequency patterns.