Fine structure and X-ray microanalysis of silicified woods from a Tertiary basin Pohang, Korea by scanning electron microscopy

Anatomical descriptions are provided on silicified woods from a Tertiary basin Pohang, Korea by scanning electron microscopy and X-ray microanalysis. The silicified woods appeared to retain the original exterior morphology of the once grown trees, and exhibited various colors on the surface. As a component of the axial system in the secondary xylem, pores were oval to globose and measured approximately 200-300 μm in diameter in transverse planes. Seemingly bordered pits were also frequently observed in the tracheary elements. As a component of the axial system in the secondary phloem, sieve elements were found to have many sieve pores that were filled with numerous fine particles. In tangential planes, rays in the vascular cambium were approximately 500 μm long, and usually several cells wide (multiseriate). Meanwhile, several forms of microbial growth such as bacterial chains and hyphal growth of either fungi or actinomycetes were evident in the vessel lumens of unpolished silicified wood pieces. Some fracture surfaces were mainly characterized by the occurrence of polyhedral crystals, probably quartz, in the fissures. By X-ray microanalysis, iron was detected from the brown-colored regions, whereas calcium was also detected together with iron in the black-colored regions. Based on the rare occurrence of tracheids as the axial system in the secondary xylem, the silicified woods in this study can be intrinsically categorized into angiosperm groups in the region.