This study was based on 148 accessions representing 39 species ofHordeum. SEM ultrastructural morphology of waxes was based on individual spikelets, whereas waxes' chemical composition was assessed from whole plants. When all the data, in the form of individual accessions, were subjected to various cluster analyses methods, no groupings were revealed. But when the data were first summarized by species and then subjected to clustering, two polythetic groups of species were detected. Group 1 is characterized by species with 40ndash;60 average alcohol content and by the common presence of diketones, whereas group 2 is characterized by species with 61 ndash; 80 average alcohol content, by the total absence of hydroxy-beta;-diketone, and almost all species without beta;-diketone. The chemical data were then subjected to classificatory discriminant analysis to assess if a single previously unclassified accession could be identified into one of the two groupings. The nature of the differences between the two groupings was described by means of a canonical discriminant analysis. Mostly only plates and filaments were detected, and in many accessions the filaments were widened, appeared platelike, and were characteristic for one group. Presence of beta;-diketone varied within species.Hordeum violaceumwas found to be unique in chemical composition.
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