ULTRASTRUCTURE AND CHEMISTRY OF THE CELL-WALL OF THE MOSS RHACOCARPUS-PURPURASCENS (RHACOCARPACEAE) - A PUZZLING ARCHITECTURE AMONG PLANTS

The architectural, compositional and functional characteristics of the cell walls of the leaves of the moss Rhacocarpus purpurascens (Brid.) Par. have been analysed by scanning and transmission electron microsc opy, wall-extraction methods, nuclear magnetic resonance (NMR) spectro scopy, and water-retention experiments. Four-layered cell walls with a peculiar architecture which, so far, appears to be unique among plant s were apparent. The architecture of the walls was not affected by seq uential wall-extraction procedures. Subsequent analysis of the residua l pre-extracted walls by classical spectro-photometrical methods revea led that the walls are composed of mainly lignin, hemicellulose and ce llulose in a ratio of about 9:8:5, determining their integrity. This w as supported by NMR spectroscopy. The resonance spectrum showed variou s characteristics typical of lignin; however, some specific peaks asso ciated with lignin were missing. The walls exhibited no particular pro perties for external water conduction but seem to be adapted to rapid absorption of fog, dew, or rain.