Anticlinal Cambial Divisions

Abstract

Sachs (1878) introduced the terms anticlinal and periclinal with reference to the division planes of cells in the shoot apex. The terms were later adopted for the division patterns in cells of the lateral meristems. Anticlinal division is the process by which new cell files are added to the cambial layer (Figs. 6.1, 6.2, 6.11, 6.49, 9.6B). These divisions are sometimes referred to as pseudotransverse and multiplicative, and in the older literature as radial. Radial as opposed to tangential cell division was one of the criteria Sanio (1873) used to identify cambial initial cells in Pinus sylvestris. According to Sanio, each time a cambial initial cell divided radially, a new file of initial cells was produced that in turn gave rise to a new file of wood and bast daughter cells. The initial cell could then be located retrospectively by the doubling of a cambial initial (Fig. 6.2A). Because doubling of the radial file occurred in both wood and bast, Sanio concluded that the radial division must have taken place in the initial cell. Mischke (1890) verified this fact in Picea abies as well as in P. sylvestris by agreeing that radial divisions were confined to cambial initial cells. Hartig (1855a, 1859a, 1878), however, held fast to his view of a biseriate cambium (Chap. 4.1.1). He believed that radial increase of the cambium occurred by “diagonal segmentation” of each member of the “Muterfasernpaare”, or mother-fiber pairs (Fig. 3.5), but tangential increase occurred by “radial segmentation” of the same mother fibers. According to this scheme, a continuous double file from wood to bast across the cambium would require simultaneous radial division of both members of the mother-fiber pair, a rather unlikely event.