Comparison of trichomes and their secretion from Dendranthema indicum and D. indicum var. aromaticum

Morphological structure and trichome density of leaves at different age and position in Dendranthema indicum and D. indicum var. aromaticum, were compared by analyzing the type and content of the excretion through GC-MS. The results showed that there were two types of glandular trichomes. One was T-shaped non-glandular hairs without the secretion function, and the other was capitate trichomes with the secretion function. There were little difference between upper and lower epidermis on the density of T-shaped non-glandular hairs, while the capitate trichomes were mainly concentrated in the lower epidermis. There were 73 compounds found in the leaf secretion of the two plants, which included mostly terpenoids and their derivatives, and 18 compounds were shared by the two plants. There were 48 and 43 compounds identified from D. indicum and D. indicum var. aromaticum, respectively, and these compounds constituted 90.96% and 84.33% respectively of the total content of leaves surface exudates.