Chemotaxonomy of Some Paleozoic Vascular Plants. Part III. Cluster Configurations and Their Bearing on Taxonomic Relationships

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Abstract
Chemical data are given forSciadophyton, Eogaspesiea,Lepidodendropsis, Triphyllopteris, Chlidanophyton andDrepanophycus. The participation of these taxa within clustering analysis is shown to generate a cluster referable tentatively to the lycopods. Introgression of clusters representative of some major plant groups (e.g., zosterophyllophytes with the lycopods, and the trimerophytes with the progymnosperms) may reflect fortuitous statistical relationships referable to different states of preservation orbona fide phylogenetic trends. Weighting of the data is shown to result in the greater resolution of clusters, while sample size (presently 34 taxa) demonstrates a considerable effect on statistical relationships. Thermolytic alterations of extant plant materials, when incorporated within fossil plant ordination diagrams, are shown to provide internal monitors allowing for a more precise evaluation of taxonomic-chemical relationships.