Morphology and secretion of glandular trichomes in Tamus communis

Light and scanning electron microscopical investigations were carried out to study distribution, morphology and secretion of glandular trichomes during leaf development in Tamus communis . During leaf growth glandular trichomes arise continously from single protodermal cells. At maturity, they are composed of a 6-celled gland head, a secretory neck cell, an "endodermal" cell, and one basal or reservoir cell. During the early stage of secretion, several regularly arranged crater-like pores differentiate on the cuticular surface of the gland head. Through these pores (1–1.5 μm in diameter), the secretion flows out as a thin film or as rods (0.4 μm in diameter) spreading on the trichomes and on the leaf surface. Histochemical tests indicate that the secretion is composed of a small amount of carbohydrates and an abundant fraction of lipophilic material. Proceeding towards senescence, the wall degeneration of the gland head gives rise to a strong histochemical reaction for insoluble polysaccharides. The results presented are compared with those of other investigations on the pattern of secretion in glandular trichomes.