DISTRIBUTION AND DIFFERENTIATION OF THE LATICIFER SYSTEM IN CHAMAESYCE THYMIFOLIA (L.) MILLSP. (EUPHORBIACEAE)

Leaves and stems of Chamaesyce thymifolia (L.) Millsp. (Euphorbiaceae) were analysed using light and electron microscopy with special emphas is on the distribution and differentiation of non-articulated laticife rs. Stem laticifers were found among parenchyma cells of the cortex. L aticifers formed a discontinuous ring in the boundaries of primary phl oem and branching into the cortex. In leaves, they formed a network in the mesophyll. In the vascular system, they appeared close to the phl oem. Laticifer tubes were branched, forming a network in both organs. The development of C. thymifolia laticifers showed two distinct stages : undifferentiated and differentiated ones. The undifferentiated latic ifers were characterized by electron-dense cytoplasm, a nucleus, abund ant mitochondria, rough endoplasm reticulum and a considerable number of small vacuoles. During the laticifer tube development, a gradual de generation of organelles was observed while a central vacuole with lat ex particles was formed. The differentiated laticifers presented intac t cell membranes, cellular debris and an accumulation of latex particl es inside the tubes. Plasmodesmata and primary pit fields could not be observed between the laticifer and the adjacent parenchyma cells. Dev eloped laticifers presented peculiar cell walls that were thicker than the adjacent cell walls. Various morphological types of starch grains were observed in the C. thymifolia latex.