A Study on the Micromorphological and Beaded Stamen of Three Species of Pogostemon Desf. (Lamiaceae Linn.) in Assam, India

Abstract

The morphology and distribution of the trichomes on the aerial parts and the feature of moniliform hairs in the stamen of Pogostemon Desf. of Assam, India were studied to understand the significance of these characters for taxonomic purposes. The three species studied are Pogostemon brachystachyus Benth., Pogostemon quadrifolius (Benth.) F. Muell, and Pogostemon strigosus (Benth.) These species of Pogostemon Desf. were mostly terrestrial while few species growing in marshy areas also. The trichomes on leaves and the moniliform hairs or beaded stamen of all the three species were investigated by both Light microscope and Scanning Electron Microscopy (SEM). The stamen with hairs was considered a unique feature that makes it a distinct genus in the family Lamiaceae, and also helps in the identification. The main types of trichomes that were distinctively observed on the leaf surfaces are, simple non-glandular unicellular and multicellular trichomes and peltate, glandular trichomes. Moniliform hairs and trichome morphology of Pogostemon brachystachyus, Pogostemon quadrifolius, and Pogostemon strigosus have not been studied previously in the study area and such investigations on Pogostemon in the study area are rather limited.