CONCERNING THE SINUOUS SHAPE OF LEAF EPIDERMAL CELLS

Abstract

The geometric features of the sinuous shape of intercostal epidermal cells of the upper epidermis of the leaf of the fern Dryopteris thelypteris (L.) were studied. These cells have an average and probability distribution for the number of anticlinal walls similar to those in tissues expanding in two dimensions as reported earlier. No angles between anticlinal walls were <90° or >180° thereby indicating that growth stresses do not alter the shape of cells during the final expansion stage of development. Both the number of convex and concave lobes per cell approaches the binomial expansion of a2(p(a)+q(b))4 while the formula a4(p(a)+q(b))8 describes the distribution for all lobes. Rare gametophtyes were found in which the cells were transformed into sporophytic, leafy types including xylem, spines and sinuous epidermal cells. The occurrence of this last feature indicates that the wavyness of epidermal cells can be achieved in an isolated layer of cells. The data best fit the hypothesis that each cell regardless of size and shape produces four growth centres, each of which arrives at a cell wall site by chance movements and forms either a concave or convex lobe. Copyright © 1976, Wiley Blackwell. All rights reserved