Observation au Microscope Électronique à Balayage des Formations Cireuses Épicuticulaires (Feuille-Tige-Cône Femelle) chez Podocarpus macrophyllus (Thunb.) Don var. angustifolius Blume, Podocarpacées.

Abstract

Epicuticular wax deposits of Podocarpus macrophyllus var. angustifolius are present on the whole of the epidermal surface (leaf — shoot — female cône); the greatest density is found in the stomatal antechambers. Wax structures are always hollow, smooth or warty tubes of which the dimensions differ with organ or part of organ observed. The wax crystals are distributed successively in isolated, continuous and discontinuous deposits; they were transformed by development in vesicles, welding and dissolving into altered forms: plates, crusts and tubercules. Their dimensions constitute an element of comparative organogeny and confirm the similarity of the foliar and receptacular structures. The great importance of the atmospheric factors in the formation of altered forms is demonstrated. The aspect and the structure are not essentially different of others epicuticular waxes of Gymnosperms; it is possible however to establish points of similarity at this subject with the genus Taxus. On the taxonomic point of view, we propose to study this problem with statistical measures of dimensions, density and distribution in association with biochemic characters.