Abstract
The anatomical structure of fusiform ray was examined by scanning electron microscopy (and microscopic images were analysed by image analyser) to explain the differences in radial fluid uptake between the extremes in the radial treatment data, i.e. between the selected trees of QCI (Queen Charlotte Islands in Rhondda, South Wales) and SO (South Oregon in Dalby, North-East England) planted in the UK. The ray structure of these two seed origins was examined microscopically and different patterns of ray composition were observed. The most important anatomical features influencing radial permeability were the nature of fusiform ray, and the condition of the resin canals, epithelial cells and intercellular spaces in particular.