The cuticle of the Buxbaumia viridis sporophyte

The sporophytes of Buxbaumia viridis are covered with a cuticle-like skin, which is peeling off when the capsules are ripe. Scanning electron microscopy (SEM) analysis showed that the supposed peeling of the cuticle of ripe capsules is not restricted to the cuticle, but to the complete epidermis. Additionally the SEM investigations showed that the capsule epidermis is covered by epicuticular wax crystals in different morphologies. Wax crystal morphologies indicate the presence of massive wax layers with small embedded and superimposed platelets and granules on top. For bryophytes such wax crystals were so far reported only from the Polytrichales, but they are common wax types of various groups of several phanerogams. Based on these micro-morphological markers the phylogenetic relationship between the cuticles of moss sporophytes and tracheophytes is discussed here.