The flower anatomy of five species of Myrteae and its contribution to the taxonomy of Myrtaceae

Considerable effort has been spent towards understanding the phylogeny of Myrteae, and based on the phylogenetic data presently available the traditional subdivision of Myrteae into three subtribes is not supported. The present paper aims to assess the usefulness of floral characters in distinguishing five species that represent five of the six South American clades of Myrteae (Myrtaceae). Floral buds and flowers of Campomanesia adamantium, Eugenia pitanga, Myrceugenia alpigena, Myrcia multiflora and Myrciaria cuspidata were collected from individual plants growing in the Cerrado (Brazilian/Central South American savanna). Among these species, the perianth of E. pitanga is the most distinct due to its vasculurization and pilosity. The hypanthium is thickest in C. adamantium and M. alpigena, while M. delicatula possesses tangentially elongated cells. Anthers do not exhibit much variation among the studied species, while M. alpigena is the only species with trichomes and secretory cavities distributed throughout the mesophyll of the outer wall of the ovary. The ovaries of all of the studied species exhibit vascularization in the form of a single ring of larger-sized bundles. Comparative analysis of these floral structures demonstrates that they are useful in separating these species, and thus the subtribes, of Myrteae.