Areoana analysis of the cell structure, using an example of reconstruction of leaf morphogenesis in paleozoic mosses of the order protosphagnales

Late Paleozoic protosphagnalean mosses are characterized by cell dimorphism similar to that of the extant genus Sphagnum . The difference between them is the fact that the protosphagnalean dimorphism appears at the latest stages of leaf development. Before the last three divisions of leaf cells, the leaf areolation is identical in structure to bryalean mosses with uniform cells. In young leaves of protosphagnalean mosses, cell areolation is also uniform. Dimorphism is observed only occasionally in a part of individual leaves of protosphagnalean mosses and it also appears in the course of the last three cell divisions. A hypothesis for the origin of sphagnaceous mosses from Protosphagnales as a result of anaboly is proposed, supporting the idea of Neuburg that the latter are ancestral to the former. The diversity of cell dimorphism in various genera of protosphagnalean mosses shows the same triad/tetrad-block pattern, differing mostly in quantitative characters of cell proportions.