ABSTRACT
Using the luminescence technique, the glandular hairs of Sigesbeckia jorullensis Kunth (Asteraceae) fluorescence and composition of essential oil at the flower and leaf development were studied (Heinrich et al., 2002). The hairs showed a subcuticular space filled mainly with essential oil, yellow coloured cells of the upper layer, green cells of the lower layers and a long stalk. Lipophilic droplets are visible on the cuticle of the subcuticular space. Blue fluorescence was observed for lipophilic materials under UV light (365/395/420). Red autofluorescence of chloroplasts was also seen both in the lower layers of the head and stalk cells. Even in young hairs the apical layer did not contain chlorophyll, and the bright blue autofluorescence indicates lipophilic material. The upper head cells stained more intensely with Sudan black B than the lower ones. Yellow secondary fluorescence indicated the presence of flavonoids in the head cells, and of flavonoid aglycones in the secretion products on the surface of the head and stalk cells. Flavonoids were present in vacuoles, whereas the inner part of the cells, where the nucleus is surrounded by plastids, is free of flavonoids, as indicated by the lack of secondary fluorescence.
