title: Systematic significance of leaf epidermal features in holcoglossum (orchidaceae).
abstract: Determining the generic delimitations within Aeridinae has been a significant issue in the taxonomy of Orchidaceae, and Holcoglossum is a typical case. We investigated the phylogenetic utility of the morphological traits of leaf epidermis in the taxonomy of Holcoglossum s.l. by using light and scanning electron microscopy to analyze 38 samples representing 12 species of Holcoglossum, with five species from five closely related genera, such as Ascocentrum, Luisia, Papilionanthe, Rhynchostylis and Vanda. Our results indicated that Holcoglossum can be distinguished from the related genera based on cuticular wax characteristics, and the inclusion of Holcoglossum himalaicum in Holcoglossum is supported by the epidermis characteristics found by LM and SEM. The percentage of the tetracytic, brachyparacytic, and laterocytic stomata types as well as the stomata index and certain combinations of special wax types support infrageneric clades and phylogenetic relationships that have been inferred from molecular data. Laterocytic and polarcytic stomata are perhaps ecological adaptations to the strong winds and ample rains in the alpine region of the Hengduanshan Mountains.
authors.affiliation: College of Chinese Medicine, Shanxi University of Traditional Chinese Medicine, Taiyuan, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Fan
authors.affiliation: College of Chinese Medicine, Shanxi University of Traditional Chinese Medicine, Taiyuan, China.
authors.forename: Runli
authors.initials: R
authors.lastname: He
authors.affiliation: College of Environmental Science and Resources, Shanxi University, Taiyuan, China.
authors.forename: Yinbo
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Systematics and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Jin
mesh_terms: D029595:Orchidaceae / Q000033:anatomy & histology* / Q000145:classification*; D010802:Phylogeny; D054046:Plant Stomata / Q000033:anatomy & histology*