Pericarp structure and myxocarpy in selected genera of Nepetoideae (Lamiaceae)

Abstract

The pericarp structure has been analyzed in 37 species representing 13 genera from four tribes of Nepetoideae (Lamiaceae). 11 species are endemics of Balkan Peninsula or other Mediterranean regions. Basically, the pericarp was similar to other Nepetoideae by having exocarp, mesocarp s. str., vertically arranged bone cells and thin innermost cell layer. The ratio between pericarp thickness and nutlet size was the highest in Mentha spp. According to this parameter Micromeria species belonging to different sections could be distinguished. Acinos spp. were characterized by the thickest sclerenchyma in ratio to pericarp thickness. Crystals were present within sclerenchyma region in genera Mentha, Melissa, Nepeta and Prunella. The mucilage production has also been tested. Most of the studied species produced mucilage when becoming wet. The strongest mucilage reaction showed Acinos and Prunella. Pericarp characters studied are of taxonomical interest. They were mainly correlated with the generic or infrageneric classification of some genera.