Cyperus is a Pantropical genus and the second richest in species in Cyperaceae. It encompasses about 550 species worldwide, with about 100 of these occurring in Brazil. Studies on the taxonomy of this genus are scarce and punctual in Brazil. In this study, the occurrence of species was surveyed through 27 collecting expeditions across different regions in the state of Rio Grande do Norte and analyzis of specimens of several herbaria. Twenty four species of Cyperus were identified, including six new occurrences and one new species, here described, but that will be properly published in other work. This study includes a dichotomous key for the identification of the species, as well as illustrations, descriptions, taxonomic comments and geographical distribution.

This article describes the riparian vegetation of a river in the Rio Grande do Norte state for the first time. This is a seasonal river in the semiarid region of the Caatinga biome. The study is based on data from herbarium collections and new expeditions from July 2007 to October 2008. Two hundred and forty seven taxa were recorded and of these, 116 are herbs and three of which are epiphytes, 25 sub-shrubs, 77 shrubs or trees, 26 lianas, one parasite, and two palms. This list of species of riparian vegetation in the river Apodi-Mossoró was compared with only two available lists from rivers in the northeast with similar environmental characteristics and showed a low similarity. This study points to the need for preservation of the species and remnants of riparian vegetation of the river Apodi-Mossoró and to increase efforts in the study of this vegetation type.

New records of Poaceae in Brazil and Bolivia are documented from expeditions, collections and review of herbarium specimens. Eleven new records are confirmed and comments, IUCN Threatened Species Categories and illustrations for these taxa are provided. Mesosetum comatum and M. filifolium are new records for Brazil, and M. ansatum is a new record for Bolivia. Paspalum burchellii, P. lepton, P. oteroi and P. trinitense are new records for Bolivia.

Mesosetum is a Neotropical genus with 25 species, and 21 of them occur in Brazil. Mesosetum forms a clade closely related with Keratochlaena rigidifolia and Tatianyx arnacites. The objective of this work was to establish the taxonomic value of the upper anthecium micromorphology for the group. A total of 96 specimens, representing all Mesosetum species (except M. wrightii), K. rigidifolia and T. arnacites were examined under a scanning electron microscope (SEM). PCA and UPGMA analysis were applied using the micromorphological characters. Fifithteen useful taxonomic characters were identified. We highlight the following characters to distinguish the Mesosetum species: the presence, type and distribution of papillae on the abaxial surface of the upper lemma; the presence of unicellular macrohairs and bicellular microhairs; presence or absence of silica cells and the structure of the germination lid. The present work shows that the micromorphological characters identified are important taxonomically at the specific level, allowing the species identification in many cases.

A new species, Cyperus potiguar, is here described and illustrated. It is a perennial species morphologically related to C. alvesii and C. ligularis, but can be recognized by spikelet size, number and size of glumes, and length of rachilla internodes. It is found in the semi-arid vegetation of northeastern Brazil, locally called Caatinga.

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-(Cyperaceae in the Apodi-Mossoró River, Rio Grande do Norte State, Brazil). The Apodi-Mossoró River, located in the Caatinga biome, has its course characterized by diverse landscape sand humid environments, as well as by many members of the family Cyperaceae. Studies on the flora of Cyperaceae are scarce in northeastern Brazil and nonexistent for Rio Grande do Norte State. Twenty-one botanical expeditions were undertaken in this area during the period from July 2007 to May 2008 on four main points in the municipalities of Felipe Guerra, Governador Dix-Sept Rosado, Luís Gomes, and Mossoró. Seven genera and twenty-five species of Cyperaceae were found in the Apodi-Mossoró River, twenty-one of which are new records for Rio Grande do Norte State.This figure more than doubled the number of species of the family known to occur in this Brazilian State. Botanical descriptions, taxonomic comments, identification keys, and illustrations are provided.

4 e na linhagem monoespecífica com x = 13 provavelmente ocorreu uma expansão do tamanho do genoma após os eventos de disploidia descendente. Foi verificada uma redução ix do genoma dos poliploides naturais, sugerindo que já houve algum grau de diploidização após o evento de poliploidização. Esta diploidização também suporta a estabilidade meiótica e alta fertilidade do pólen observadas na maioria dos poliploides de Mesosetum.