The relationship between the arrangement of rays in secondary phloem and grain inclination in the wood of Pinus silyestris L. and Picea abies Karst

Abstract

The arrangement of rays in cross sections of secondary phloem and the wood grain on the tangential and radial surfaces of wood columns from Pinus silvestris and Picea abies was studied. It was found that in most cases the rays were slanted and deviated from the geometric radius in either the S-direction (to the left) or in the Z-direction (to the right) when the cross section of the stem was observed from above. The S-type deviation dominated in those stems in which the wood grain in the peripheral parts was of the S-type (left-oriented), whereas the deviation of rays in the Z-direction was found to dominate in those objects, in which the wood grain in the peripheral parts of the stem was of the Z-type (right-oriented).