Comparative morphology of the leaf epidermis in Lobelia (Lobelioideae) from China

The leaf epidermal morphology of 38 samples, representing 22 Lobelia species from China, was studied using light microscopy and scanning electron microscopy. The stomata and other epidermal features were largely consistent within species, and therefore represented good characters for taxonomic purposes. Diagnostic characters of the leaf epidermis were used to differentiate species of Lobelia. The species pairs L. clavata and L. pyramidalis, L. alsinoides and L. terminalis, and L. davidii and L. erectiuscula, were differentiated using leaf epidermal characters. Results at the micro-structural level partly supported the current subdivisions of Lobelia. Previous taxonomic revisions of Lobelia in China were evaluated based on species epidermal characteristics. The results supported the recognition of Pratia merged with Lobelia, and of L. chevalieri as a distinct species. Lobelia brevisepala should not be included in L. montana. The status of Lobelia in the evolutionary history of Campanulaceae was assessed. The Lobelia species investigated retained many primitive leaf epidermal features.