Meetings of the Royal Botanical Society of The Netherlands

A selection of peatified plant tissues, handpicked from a Dutch peat deposit, were anatomically and mass spectrometrically characterized and compared with native tissues. In this way, insight is obtained in the chemical and anatomical selectivity of the decomposition process in peat deposits. A selective removal of polysaccharides and a structural modification of the lignin macromolecule are observed in both peatified Calluna stemwood and Ericaceous rootwood. These chemical changes coincide with severe anatomical changes, although the state of preservation between different wood forming tissues is rather variable: in peatified Calluna fibres, the combined S,/S2 layer is gone whereas the S3 layer and compound middle lamella are preserved. Sporadically, fibres with a higher or lower grade of decomposition are observed. The wood vessels, showing swollen and gelified cell walls, are better preserved than the surrounding fibres. A uniform thinning of the cell wall is observed in the rootwood fibres, which are often better preserved in the centre of the root. Decomposition resistent wood vessels, as found in Calluna stemwood, are not observed in the wood of the root.