CAMBIAL BEHAVIOR WITH REFERENCE TO CELL LENGTH AND RING WIDTH IN PICEA

Abstract

This study deals with the relationships between length of wood cells, width of annual rings, and frequency of multiplicative (pseudotransverse) divisions in fusiform cambial cells of Picea. Species investigated were P. engelmanni, P. glauca, P. mariana, and P. sitchensis. Observations were based on the recent growth of trees 10–20 in. in diameter, and in the case of P. sitchensis included trees up to 7 ft in diameter. In general, maximum cell length was associated with a ring width of 1–2 mm. Cell length declined with increase in ring width, and also decreased slightly when ring width fell below the optimum level. The frequency of pseudotransverse divisions in the cambium remained at a more or less uniform rate in trees with rings 2–8 mm wide, but rose sharply as ring width dropped below 1 mm. The slight reduction in cell length in narrow rings was apparently associated with the rise in frequency of multiplicative divisions in the cambium. Maximum cell length was observed in P. sitchensis. The shortest cells and lowest frequency of multiplicative divisions were noted in P. engelmanni. As ring width decreased a higher proportion of the pseudotransverse divisions occurred during the late seasonal growth. The orientation of the partition in pseudotransverse division tended to be unidirectional, but reversals in direction of tilt occurred after varied intervals.