Characteristics of the submicroscopic structure of the leaf epidermis in <i>Hypodematium</i> (Hypodematiaceae) from China and its taxonomic significance

We carefully observed the submicroscopic structural characteristics of the hairs of the stipe, rachis, costae, fronds and indusia of 15 species of Hypodematium from China and photographed them under an anatomical microscope and scanning electron microscope (SEM). The results show that the hairs on the epidermis of the leaves of the 15 species could be divided into two types: rod‐shaped glandular hairs and non‐glandular hairs, which were respectively distributed in various parts of each species. The type, density, length and thickness of the hairs were stable within species, but there were significant differences between species. The species could be divided into three groups based on their hairs: 1) H . sinense and H . fordii with rod‐shaped glandular hairs; 2) H . crenatum , H . hirsutum , H . guilinense and H . zhangii with non‐glandular hairs; 3) H . confertivillosum , H . squamuloso ‐ pilosum , H . mengshanensis , H . shandongense , H . gracile , H . glandulos o‐ pilosum , H . jianxiuii , H . chingii and H . taishanensis with rod‐shaped glandular hairs and non‐glandular hairs. These submicroscopic structures, combined with palynology, provide characters for species identification and interspecific classification. This enables the development of plant taxonomy from the traditional classification stage to a new stage based on SEM studies of submicroscopic structures. It is of great significance not only for the protection and development and utilization of plant resources in this genus, but also for other groups and families.