MEMBRANES AND ORGANELLES OF DEHYDRATED SELAGINELLA AND TORTULA RETAIN THEIR NORMAL CONFIGURATION AND STRUCTURAL INTEGRITY - FREEZE-FRACTURE EVIDENCE

Dry (7-10% water content) leaves of the spikemoss Selaginella lepidophylla (''resurrection plant'') and of the desiccation-tolerant moss, Tortilla ruralis were examined by freeze fracture electron microscopy. As has been described for dry seeds, the cells of these dehydrated leaves were shrunken, with highly convoluted walls and membranes. The membranes of all samples had a lipid bilayer organization with dispersed intramembranous particles (IMPs). Lipid droplets were very closely associated with the plasmamembrane. Chloroplasts were surrounded by a double membrane envelope and contained well-organized grana. Mitochondria were irregular in outline, and endoplasmic reticulum and cytoplasmic vesicles were present.