The Comparative Extent of Variation of Free Amino Acids and Certain “Secondary” Substances Among Cassia Species

A lston , R. E. (U. Texas, Austin), and H. S. I rwin . The comparative extent of variation of free amino acids and certain “secondary” substances among Cassia species. Amer. Jour. Bot. 48(1): 35–39. Illus. 1961.—Five species of Cassia , selected to include 4 sections of the genus, were examined by chromatographic methods for free amino acids and for substances visible in ultraviolet light, visible light and after spraying with a general reagent for phenols. The latter, representing a heterogeneous group, are referred to as “secondary” substances (implying that they are not intimately involved in basic energy transfer or assimilative activity of all tissues). Among the species examined there was definite but only moderate variation in the free amino acids present, and differences were predominantly quantitative. In contrast, a minimum of 25 “secondary” substances appeared on the chromatograms when viewed in ultraviolet light and ammonia vapor, with no more than 9 of the spots present in a single species. While free amino acid patterns may be useful in themselves, it seems that patterns of variation of “secondary” substances offer a greater potential in taxonomic work.