Abstract:

An electron microscopic study was undertaken on the pit structure of 15 families, 28 genera and 45 spelles in hardwoods of China using ultrathin section and direct carbon replicas. Intervascular pit membranes with torns were found to be present in 10 species from 8 genera belonging to 4 families, but pit membranes were flat in the remainder. Microfibrils orientation on the pit membranes could be classified in 3 type:random; radio; paralled orientation. The vestures and warts in intervascular pit chamber separately ware fourd in 5 and 19 species. The above-mentioned characters have a value for the classification of wood. The intervascular pit membranes of bordered and half bordered pits in 17 fresh and delignified woods contain distict openings which diameter were 0.04-0.19μm. Plasmothesmata and fine pore were present on the simple pit membrand of fresh woods. The variation in phylogeny of the pit membrane of bordered pits in hardwoods was also discussed.

Key words: Hardwoods, Ultrastucture, Pit, Torns, Opening of pit membrane