The transition from nonstoried to storied cambium in Fraxinus excelsior. I. The occurrence of radial anticlinal divisions

Abstract

Cell size and arrangement in layers of terminal late xylem parenchyma were interpreted as an historical record of certain types of divisions in the cambium. This allowed study of anticlinal divisions of fusiform initial cells in the cambium of Fraxinus excelsior L. Two types of anticlinal divisions were recognized: oblique (pseudotransverse) and radial (longitudinal). Type designation is, however, arbitrary, since many intermediate configurations between oblique and radial were found. With the exception of radial–lateral divisions, both oblique and radial divisions can be classified as of the left (S) or right (Z) orientational type. The types were nonrandomly distributed. A statistically significant inverse relation was found between the relative length of the anticlinal partition (RLAP) and the length of the dividing cell. Thus, short cells tend to divide radially and longer ones to divide obliquely. As an indirect result, Fraxinus cambium is a mosaic of storied and nonstoried local areas. Consequently, Fraxinus cambium, having an average (but highly variable) RLAP of just over 50%, represents an intermediate between the storied and nonstoried condition.