Scanning Electron Microscopy of Mature Douglas-Fir Earlywood Intertracheid Pitting

Scanning electron micrographs of nlature earlywood intertracheid pitting of Douglas-fir, Pseudotsuga ~nenzeisii (Mirb.) Franco, demonstrate the advantages and limitations of the scanning electron lnicroscope.The micrographs portray the variation encountered in pit membrane structure.The micrographs are interpreted to support Harada and CBtit's ( 1967) proposed organization of the pit border and, at least in some instances, the aggregation of primary wall fibrils to form large margo strands.