title: Floral nectary, nectar production dynamics, and floral reproductive isolation among closely related species of Pedicularis.
abstract: Floral nectar is thought to be one of the most important rewards that attract pollinators in Pedicularis; however, few studies have examined variation of nectary structure and/or nectar secretion in the genus, particularly among closely related species. Here we investigated nectary morphology, nectar quality, and nectar production dynamics in flowers of Pedicularis section Cyathophora. We found a conical floral nectary at the base of the ovary in species of the rex-thamnophila clade. Stomata were found on the surface of the nectary, and copious starch grains were detected in the nectary tissues. In contrast, a semi-annular nectary was found in flowers of the species of the superba clade. Only a few starch grains were observed in tissues of the semi-annular nectary, and the nectar sugar concentration in these flowers was much lower than that in the flowers of the rex-thamnophila clade. Our results indicate that the floral nectary has experienced considerable morphological, structural, and functional differentiation among closely related species of Pedicularis. This could have affected nectar production, leading to a shift of the pollination mode. Our results also imply that variation of the nectary morphology and nectar production may have played an important role in the speciation of sect. Cyathophora.
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.|University of Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Ya-Nan
authors.initials: YN
authors.lastname: Liu
authors.affiliation: Institute of Alpine Economic Plant, Yunnan Academy of Agricultural Sciences, Lijiang, 674100, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
authors.forename: Fu-Sheng
authors.initials: FS
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
authors.forename: Xiao-Quan
authors.initials: XQ
authors.lastname: Wang
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology; D002241:Carbohydrates / Q000032:analysis; D035264:Flowers / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure; D032262:Pedicularis / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure; D057048:Plant Nectar / Q000096:biosynthesis*; D054817:Pollination; D060047:Reproductive Isolation; D013045:Species Specificity
chemical_list: D002241:Carbohydrates; D057048:Plant Nectar
keywords: Pedicularis; nectar; nectary; pollination; reproductive isolation; section Cyathophora; speciation