Relationship in annual species of Medicago. VI. Two-dimensional chromatography of the phenolics and analysis of the results by probabilistic similarity methods

Abstract

As part of a programme initiated to secure a better understanding of the relationships among annual species of Medicago, phenolic substances were investigated in leaf hydrolysates of 24 annual and 10 perennial species by means of the two dimensional paper chromatographic technique. A total of 53 compounds were observed in the two-dimensional chromatograms from the Medicago species and from some species of Trigonella, Melilotus, and Lotus included for comparison. A few of these compounds were tentatively identified. The data were analysed by use of the probabilistic similarity index of Goodall (1964), which permits significance tests of hypotheses concerning the classification proposed and is believed to be more sensitive than nonprobabilistic similarity indices in distinguishing smaller groupings.

Significant clustering of the Medicago species in relation to Trigonella, Melilotus, and Lotus species could be recognized. With few exceptions there was little variation of the phenolic pattern among accessions of the same species but at the species level no clear correlation was observed between the degree of exomorphic differences, as expressed by the current taxonomic and phylogenetic interpretation of the genus, and the differentiation of the phenolic patterns.

The influence which some of the results may have upon the systematic and phylogenetic interpretation of the genus and upon future research is discussed.