Perforation Plate Development in Knightia excelsa R. Br. : A Scanning Electron Microscope Study

Abstract

The development of perforation plates in the vessels of Knightia excelsa R. Br. is described. The primary walls and middle lamella in the region of the perforation remain intact late in the differentiation of the adjoining vessel members. Only after the secondary wall has been laid down, forming prominent borders over this perforation partition, does the latter show any sign of degeneration. The breakdown process involves a change in the nature of the partition, which becomes granular in appearance. Small holes then develop in it before its final disappearance.