Abstract:Developmental anatomy of trichomes （glandular hairs and non-glandular hairs） on the leaves and stems ofLanvandula pinnata was studied. It was shown that all trichomes are originated from the protodermal cells, but their structure, development and function are distinctly different. There are two types of glandular hairs, capitate glandular hairs and peltate glandular hairs, all of which are composed of a basal cell, a stalk cell and apical secretory cells. There are 1 or 2 secretory cells in a capitate glandular hair but 8 secretory cells in a peltate glandular hair. However, Non-glandular hairs consist of 3-20 cells, they can be divided into 3 kinds： uniseriate, two-branched, three-branched and more branched arborization. In non-glandular hairs, the apical cells become tapered. The glandular hairs are formed by second successive periclinal divisions of the initial cell, and because of the different meristematic state of the stalk cells and apical cells, they developed into two types, capitate and peltate. Non-glandular hairs are created from initial cells through second or more periclinal divisions and unequal divisions, then developed into several to about twenty sister cells.
