Abstract:In order to identify the original plants of traditional Chinese medicine Xihuangcao, the development of glandular trichomes on the leaves of Isodon lophanthoides var. lophanthoides was observed under light and electron microscopes. The results showed that there were two types of glandular trichomes, capitate and peltate glandular trichomes. The capitate glandular trichome was colorless and transparent, composed of one basal cell, one stalk cell and a head with one or two secretory cells, while the peltate glandular trhichome was red, composed of one or two basal cells, one stalk cell and a head with 4-8 secretory cells. The glandular trichomes were formed by second successive periclinal divisions of the initial cell, and because of the different meristematic state of stalk cell and apical cells, they developed into two types, capitate and peltate. The ultrastructural structure of glandular trichomes showed that plastid, golgi and the endoplasmic reticulum (RER) were the main secretory and transport organelles. When the peltate glandular trichomes matured, the subcuticular spaces were full of secretions. The characters of secretions might determine glandular trichomes color of I. lophanthoides var. lophanthoides.