SEQUENTIAL CHANGES IN RATE OF ANTICLINAL DIVISION, CAMBIAL CELL LENGTH, AND RING WIDTH IN THE GROWTH OF CONIFEROUS TREES

Abstract

The early growth of a tree is marked by a widening of the annual increments, a deceleration in rate of multiplicative (anticlinal) division of fusiform cambial cells, and an increase in cell length. Distance outward from the pith at which maximation in cell size occurs, and subsequent trends in cell dimensions, are apparently modified by rate of growth. Continuation of a uniform ring width through the middle to late years favors comparative constancy in rate of anticlinal division and cell size during that stage of tree development. Reduction in amount of annual increment in the late growth to the width optimal for cell extension, about 1 mm, induces a delayed and probably heightened maximation in cell length. Continued lessening in radial growth to an annual accretion of 0.5 mm or less, with the onset of senility, results in acceleration in rate of multiplicative division and reduction in cell length.