Pariana caxiuanensis (Poaceae) is described and illustrated as a new species from the Brazilian Amazon. The new species is characterized by having the leaves clustered at the apex of the leafy culm, fimbriae few to absent, dimorphic flowering culms, large ligules (2.5–4 mm long), and pubescent to hirsute synflorescences. We present a morphological description, illustrations of the new species, the conservation status assessment, and a key to differentiate P. caxiuanensis from its morphologically related congeners.

RESUMO In this study a floristic survey of species of Poaceae from the restingas and dunes vegetation of Ilha do Maranhão, located in the north of Maranhão State, was performed. Collections in the study areas and analysis of material from Herbarium MAR and SLUI was carried out. Thirty species were found, the genus Paspalum L. was the richest genus, whit four species. An identification key to the founded species, descriptions and illustrations are provided.

This study focuses on the Cyperaceae occurring in the Serra dos Martírios-Andorinhas (Serra dos Martírios- Andorinhas State Park, and São Geraldo do Araguaia Environmental Protection Area), in the São Geraldo do Araguaia municipality, state of Pará, Brazil. The Serra is in the “Deforestation Arc”, an environmentally vulnerable area with the highest deforestation rates in the Amazon Forest. The predominant phytophysiognomy is the Amazonian savanna, characterized by open environments dominated by herbaceous plants, such as Cyperaceae, represented by only four species in a previous floristic inventory. Studying the diversity of Cyperaceae allows us to a better understanding of the herbaceous layer’s dynamics and assisting in the conservation, monitoring, and management of these fascinating and peculiar environments. Therefore, 276 field and herbarium samples of Cyperaceae from Serra dos Martírios-Andorinhas were examined. Now, Cyperaceae are represented by 12 genera and 72 species in the study area, of which seven represent new records for the State of Pará. A taxonomic identification key, short descriptions with main diagnostic characters, geographic distribution, habitat data, and illustrations for all species and genera are provided.