The results of a detailed SEM study of nutlet morphology in 156 species of tribe Nepeteae (Labiatae) are presented. Two main types, smooth and sculptured, are described; within them such subgroups as reticulate, cellular, verrucose and tuberculate are defined. The taxonomic significance of these characters is discussed. Pericarp structure was investigated in 34 species. Mucilaginous tubercles were found on the surface of the nutlets in Nepeta, Drepanocaryum and Lophanthus, and their structure is described. In the 10 genera of this widespread tribe, three informal generic groups are recognized, based on a combination of nutlet morphology, pericarp structure and vegetative and floral features.
* Komarov Botanical Institute, 2 Popova Street, St Petersburg 197376, Russia.