THE MICROSCOPIC WOOD STRUCTURE OF NORTH AMERICAN SPECIES OF CHAMAECYPARIS

Abstract

Trends in variation in different parts of the tree with regard to such anatomical features as tracheid and ray cell dimensions, size and distribution of rays, size and arrangement of pits, and thickness of cell walls resemble those recorded for other Cupressaceae. Comparative data relating to homologous wood samples show slight differences in mean values between the three American species of Chamaecyparis, but the intraspecific variability is usually so extensive that the specific ranges overlap widely. No single microscopic character seems completely reliable for diagnostic purposes, but certain structural features are valuable when used together. These are the frequency of ray tracheids in newly formed rays, the thickness of the horizontal and end walls of ray parenchyma cells, the number of pits per crossing field, and the height/width ratio of ray cells viewed tangentially.