Age‐related contents of polymerized lipids in the ectohydric forest mosses Pleurozium schreberi and Hylocomium splendens

Abstract

Cell wall preparations of the ectohydric forest mosses, Pleurozium schreberi (Brid.) Mitt. and Hylocomium splendens (Hedw.) B. S. G. contain polymerized lipids consisting of hydroxy acids, dicarboxylic acids, fatty acids, fatty alcohols and unidentified components. The finding of polymerized lipids in ectohydric mosses, which have highly permeable cell walls, indicates that the polymers do not form an effective barrier against water and nutrients, at least not in the cell walls of these mosses. The youngest parts of P. schreberi and H. splendens contained 2.0 and 1.6 mg polymerized lipids, respectively, on a dry cell wall weight basis. In the senescent, greyish‐green parts of P. schreberi and in the one‐year‐old shoot tissue of H. splendens the corresponding amounts were about 1.5‐fold. In both species the increase was due to increases in hydroxy acids, particularly dihydroxyhexadecanoic acids, dicarboxylic acids, unknown components and, in the case of H. splendens, also an increase in fatty acids. The increase may be related to the maturation of the cell walls. In still older shoot parts the amounts of polymerized lipids decreased in both species, and remained low until final decay of the tissues into small particles. A slight increase in the amount of the polymerized lipid monomers was found in the oldest and most decomposed parts of H. splendens, probably indicating a better resistance to decay than for other cell wall components. These findings are discussed in relation to what is known from the ectohydric peat‐forming Sphagnum mosses.