Ocimum selloi Benth. (Lamiaceae) is native to South America and in traditional medicine has been used due to its analgesic, anti-inflammatory, and antispasmodic properties. The aim of this study was to identify the types of glandular trichomes that occur on the vegetative and reproductive organs of O. selloi and to determine trichome ontogeny. Lateral branches at the initial formation phase, fully opened leaves, flowers at different differentiation stages, and stem and inflorescence axes were analyzed under light and scanning electron microscopy. Glandular trichomes of the peltate and subsessile capitate types were observed on the stem, leaves, inflorescence axis and the adaxial surface of the sepals. On the sepals, in addition to the peltate and subsessile capitate secretory trichomes, the stalked capitate glandular trichome type was detected. Ontogeny began with the expansion of a protodermic cell, which according to the sequence of periclinal and anticlinal division (either symmetric or asymmetric) gave rise to the glandular trichomes. Differentiation of the peltate and capitate glandular trichomes was not synchronized and occurred very early in the leaf, stem and floral axis.
basil; paregoric elixir; secretory structures; medicinal plants
