Anatomical Studies in the Polytrichaceae. I. The Gametophore of Dendroligotrichum dendroides (Hedw.) Broth

The gametophore of Dendroligotrichum dendroides (Hedw.) Broth. is differentiated into a multiseriate cortical region in which is embedded a central cylinder of tissues. The central cylinder consists of a core of cells, the hydroids, surrounded by a leptome sheath of parenchyma and sclerenchyma. The hydroids are elongated cells with unpitted lateral walls and oblique primary end-walls which overlap those of adjacent cells. In this respect they are similar in appearance to the hydroids described in Polytrichum except for one important difference: the lateral walls are impregnated with lignin. The hypothesis of a water conducting role is proposed for the hydroids. Lignified cells were also found in the leptome sheath surrounding the hydroids and in the inner cortical cells. Lignin is localized in the secondary walls and adjacent primary walls. The parenchyma cells of the leptome sheath which possess oblique primary end-walls may be similar to the leptoids described in Polytrichum.