The storeyed and non-storeyed arrangement of rays in the storeyed cambium of Tilia cordata Mill.

Abstract

Due to restructuring of the cellular arrangement, rays in storeyed cambium undergo transformations, that is, uniting and splitting on the borders of storeys, when their height during development exceeds that of the storeys of fusiform cells. The primordial rays on the cambium surface have a non-storeyed arrangement. Prolonged predominance of splitting over uniting can lead to a situation in which the height of the rays does not exceed that of fusiform cell storeys. A storeyed arrangement of rays is thus formed. The maintenance of a given arrangement of rays in successive annual growths is the result of the cumulation of several traits, such as: 1) the seriation of rays, 2) the magnitude of grain inclination, 3) the rate of the restructuring of the cell arrangement. For example, the quicker a storeyed arrangement of rays will be formed the less the rays are seriated, the quicker the cells are restructured and the greater the inclination of their arrangement. The magnitude of the inclination of the grain and the rate of cell restructuring are traits connected with the arrangement of fusiform cells. The seriate nature of rays, however, is characteristic of rays and, moreover, it is a characteristic individual trait. It seems that the seriation of rays can play a valuable role in taxonomic analysis.