Variations in the Lengths of Fusiform Cambial Cells and Vessel Elements in Kalopanax pictus

Abstract

Samples of a mature specimen of Kalopanax pictus, a ring-porous hardwood, were studied to compare the respective lengths of fusiform cambial cells and vessel elements in the stem. The lengths of dormant and reactivated fusiform cambial cells were measured with a confocal laser scanning microscope in tissue that had been macerated by digestion with pectinase and in thick tangential sections. The lengths of early wood and late wood vessel elements were measured in tissues that had been macerated by Franklin's method. The vessel elements and fusiform cambial cells varied considerably in length within individual samples. The mean length of early wood vessel elements corresponded to that of fusiform cells in the dormant cambium but not in the reactivated cambium. Significant differences were observed between the mean lengths of dormant and reactivated fusiform cambial cells, between those of reactivated fusiform cambial cells and early wood vessel elements, between those of reactivated fusiform cambial cells and late wood vessel elements, and between those of early wood and late wood vessel elements. The frequency distributions of lengths of cambial cells were bimodal and differed from those of vessel elements, which more closely resembled a normal distribution. The proportion of shorter lengths was higher in the reactivated cambium than in the dormant cambium, the early wood and the late wood vessel elements. Our results do not suppot the hypothesis that the lengths of early wood vessel elements in ring-porous hardwoods change during differentiation. The similar ranges of recorded lengths suggest that short and long vessel elements might be derived directly from short and long cambial cells, respectively.