CHEMICAL CHARACTERIZATION OF THE PERIDERM TISSUE OF SOME ANGIOSPERM SPECIES - RECOGNITION OF AN INSOLUBLE, NONHYDROLYZABLE, ALIPHATIC BIOMACROMOLECULE (SUBERAN)

In order to establish the chemical relationship between the liptinitic maceral suberinite and its recent counterpart, an inventory of the co nstituents of isolated outer bark tissue (periderm) of five extant ang iosperm species was made. Samples were analyzed by means of chemical d egradation methods in combination with Curie-point pyrolysis-gas chrom atography-mass spectrometry and gas chromatrography-mass spectrometry. It was demonstrated that the periderm of the species investigated con sisted of complex mixtures of lipids and biomacromolecules which inclu de the biopolyester suberin, tannins, polysaccharides, lignin, and a h itherto unknown insoluble, non-hydrolyzable highly aliphatic biomacrom olecule, named suberan. The liptinitic nature of the maceral suberinit e can probably be explained by assuming selective preservation and con sequent selective enrichment of suberan during the processes of diagen esis. The lignin present in the periderm of extant angiosperms is of a distinctively different monomeric composition from that of the corres ponding wood with a marked guaiacyl over syringyl predominance. The pr esence of different physiological functions within the plant is offere d as explanation for this divergence.