Some fine structural observations on the rhizome ofDendroligotrichum (Bryophyta)

Summary The underground portion (rhizome) of the gametophytic axis ofD. dendroides bears anatomical resemblances to a triarch dicotyledonous root. The similarities include: 1. an epidermis producing epidermal appendages; 2. a cortex with endodermoid layer; and 3. a tri-radiate arrangement of the food and water-conducting tissue. Histochemical observations reveal that the entire radial and transverse walls of the endodermoid cells are encrusted with amorphous deposits, probably of polyphenolic nature. Casparian bands are not present as reported by earlier workers. The radial walls exhibit a fine structure of alternating electron-dense and electron-opaque lamellae. In plasmolyzed cells the plasmalemma does not adhere to the radial wall. Plasmodesmatal connections were observed in the radial and outer tangential walls of the endodermoid cells, but not in the inner tangential walls. These features of the endodermoid layer ofD. dendroides are discussed in relationship to the structure and function of the endodermis of vascular plants.