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Aerenchyma is a characteristic tissue of aquatic plants, characterized by the presence of air lacunae commonly septated by diaphragms. These are formed by one or more layers of stellate cells, which allow for the passage of gases. Most species of Eleocharis grow in wet or flooded soils and have aerenchyma in their aerial stems. However, extensive studies on this structure, which could contribute to ecological and phylogenetic studies of the group, are lacking. This work describes the structure of the diaphragm in the stem of Eleocharis species and investigates the evolution of this characteristic in the genus. Fifty-three species were analyzed under light and scanning electron microscopy. We analyzed the evolution of the characteristics by reconstructing their ancestral states based on the previously published original phylogeny. The diaphragms in Eleocharis vary mainly in the number of layers, cell shape, and cell wall thickness. The typical diaphragm of the genus is composed of three to four layers of stellate cells, with microprojections and secretory cells. The diaphragm of the group's ancestor had practically the same characteristics as the genus's typical diaphragm. [ABSTRACT FROM AUTHOR]

Eleocharis (Cyperaceae) includes more than 300 species of perennial or annual herbs, frequently found on poorly drained soils. The species are morphologicaly similar, and the taxonomy is difficult because their vegetative and reproductive structures are very reduced. Previous study on the stem architecture in the subgenus Limnochloa showed that anatomical features help in the interpretation of the evolution, taxonomy and ecological aspects of the group. Our objectives were to add new characters from the stem (= culm) structure, to explore the characters in a greater number of Eleocharis species, representatives of the other subgenera, and add these data in a new phylogenetic analysis with molecular data. The study covered 68 species obtained from herbaria and fixed material. In addition to the stem architecture, the internal organization of the tissues, the cross-section format, the presence or absence of stretched cells in aerenchyma air gaps and the plant size were included in the morphological analysis. Our data confirm that spongy aerenchyma pattern is the ancestral condition while the mixed and septate patterns occurred independent and punctually. Only the cross-section format was variable among specimens while the other characters were uniform and relevant for taxonomic use. [ABSTRACT FROM AUTHOR]

Catopsis is represented by 19 species distributed among the three Americas. Two species occurs in Brazil, Catopsis berteroniana distributed in Northeast, Southeast and South region and Catopsis sessiliflora, with a broadly distribution, also found in the North. The aim of this work was to perform a taxonomic and morphoanatomic study of the species of Catopsis occuring in Paraná state. In order to do so, botanical expeditions occurred during the periods of Jul/2013-Jun/2014 just as the visits to HUPG, MBM and UPCB herbarium. The collected specimens were identified, herborized, and deposited in the HUPG herbarium. For the morphoanatomic study semi-permanent slides were prepared from the middle region of the sheath and leaf from transverse and longitudinal sections obtained free hand and mounted in glycerinated gelatin. For Scanning Electron Microscopy analysis portions of leaf blade and sheath were dehydrated for observation. As results, we provide descriptions, period of flowering and fruiting, identification keys, geographic distribution, the ecophysiological rating, morphology and anatomy comments, and conservation status of the species. [ABSTRACT FROM AUTHOR]