Secretory Hairs of Inula viscosa (L.) Ait.-Development, Ultrastructure, and Secretion

Abstract

The leaves and young stems of Inula viscosa (L.) Ait. bear sessile and stalked secretory hairs which secrete throughout the life span of the leaf from its very early stage of development to maturity. Both types of hair possess a secretory head consisting of three types of cells: one pair of summit cells, one pair of cells below the summit cells, and three pairs of photosynthesizing cells. All head cells secrete lipids, polysaccharides, and protein. In the head cells smooth and rough endoplasmic reticulum, plastids, mitochondria, and Golgi bodies seem to be involved in secretion. The various cell pairs of the head differ in their sequence of ultrastructural changes throughout the period of secretory activity, in type of plastid and its involvement in the secretory process, and in the manner the substances secrete to the outside. At various stages of the secretory activity different cell constituents were present in abundance.