INTER-TRACHEID AND CROSS-FIELD PITTING IN COMPRESSION AND OPPOSITE WOOD OF

Abstract

Inter-tracheid and cross-filed pit pairs in compression and opposite wood of Norway spruce (Picea abies) were examined. The size, appearance, and frequency of bordered pits on the radial side of axial tracheids and their aperture specification were studied. The type, size, and number of half-bordered pits between the axial tracheids and rays per cross-field were also studied. Several techniques were employed for the measurements: Environmental Scanning Electron Microscope (ESEM), Scanning Electron Microscope (SEM), Light Microscope (LM), and the Frankling method (FM). The structure, size, and frequency of both types of the pits varied between compression and opposite wood. Fewer pits of a smaller size and a smaller aperture diameter were observed in compression wood. The uniseriate arrangement of bordered pit pairs, unpitted tracheid walls, circular- or often slit-like pit aperture, dominantly piceoid but sometimes cupressoid and occasionally taxodioid cross-field pitting, and a number of fissures on the tracheid walls and bordered pits were characteristics of compression wood.

Keywords

• Norway spruce (Picea abies)
• Compression wood
• Opposite wood
• Inter-tracheid pit
• Cross-field pit