THE ULTRASTRUCTURE OF GLANDULAR TRICHOMES OF PHILLYREA-LATIFOLIA L. (OLEACEAE) LEAVES

The anatomy and ultrastructure of glandular trichomes al different dev elopmental stages were investigated in Phillyrea latifolia L. leaves b y transmission electron microscopy and histochemical techniques. The t richome consisted of a multicellular secretory head, a unicellular sta lk and a collecting cell surrounded by epidermal cells and spongy meso phyll cells. There were numerous plasmodesmata across the cell walls o f trichome cells, and especially between the stalk cell and the collec ting cell. The collecting cell and stalk cell contained few chloroplas ts. Mitochondria, elements of the endoplasmic reticulum and small vacu oles were abundant in the secretory cells. Crystals were present in th e secretory cells and the collecting cell, especially at the mature an d senescent stages of trichome development. As the cuticle, which cove red the secretory cells, did not show pores or perforations, it is pro posed that secretion occurred by accumulation of products in subcuticu lar spaces followed by diffusion through the cuticle. Callose accumula tion was observed between the stalk cell and the collecting cell of se nescent trichomes, especially in salt-treated plants. Trichome ontogen y was accelerated in salt-treated plants. (C) 1998 Annals of Botany Co mpany.