Systematics of Plagiochila sect. Glaucescentes Carl (Hepaticae) from tropical America: a morphological and chemotaxonomical approach

The systematics of the Glaucescentes Carl, a poorly known neotropical secti on of the large genus Plagiochila, is revised based on a large set of gamet ophytic, sporophytic and chemical characters. Three species are recognized, P. buchtiniana Steph., P. longispina Lindenb. and Gottsche and P. diversif olia Lindenb. and Gottsche, the latter with two chemotypes. Twelve binomina are reduced to synonymy. The species occur in montane regions of tropical America, especially in the northern and central Andes. In addition, P. long ispina is newly reported from the Azores, where it was previously known as P. allorgei Herzog and Perss. The Glaucescentes are excellently characteriz ed by morphological and chemical features and are clearly separated from th e Contiguae Carl, a group often confused with the Glaucescentes. Morphologi cally, the Glaucescentes stand apart by the brown oil bodies, thin-walled i nner capsule wall cells and partly unequally bispiral elaters. Chemically, they are characterized by the accumulation of partially hydrogenated bibenz ylderivatives (longispinone, longispinol), 3-benzylphthalides and various f lavonoids, and by the low production of terpenoids.