Flora do Estado do Rio Grande do Norte: Mesosetum Steud. (Poaceae)
Maria Eduarda Costa Freitas
UFERSA
Palavras-chave: Mesosetum annuum, Mesosetum pappophorum, Mesosetum rottboellioides
Resumo
Floristic studies in the Caatinga are essential because they allow us to understand the diversity of species present in this unique and little-studied biome, aiding in the understanding of its structure, dynamics, and potential for sustainable use. Poaceae is a family of plants known as grasses, grasses, or turfs. They are flowering plants, often rhizomatous, annual or perennial, subwoody to woody, with life forms ranging from shrubs, trees, bamboo, herbs, lianas, vines, or subshrubs. They can live in aquatic substrates, in rocky areas, or in terrestrial areas. Mesosetum Steud. is a Neotropical genus with 28 species, of which 24 occur in Brazil and 8 in the Caatinga. Botanical collecting expeditions were carried out in the four mesoregions of the state (West, Central, Agreste, and East), exploring various types of vegetation such as Caatingas (Hyperxerophilous, Hypoxerophilous, and Seridó), Cerrado, forests of the eastern coast and humid mountain ranges of the interior (Deciduous, Subdeciduous, and Subevergreen), restingas, mangroves, riparian vegetation, freshwater vegetation, and rocky vegetation. The vouchers were deposited in the Odaci Fernandes de Oliveira Herbarium, and duplicates were donated to similar herbaria. The specimens were examined under stereoscopic specificity, identified based on specialized literature, and reviewed as species already collected from the MOSS herbarium. Field research found the following species: Mesosetum annuum Swallen, found in the Caatinga region of Serra Negra do Norte, is an annual, small, and has 2.5–12 cm inflorescences and 3.5–4 mm spikelets; Mesosetum pappophorum (Ness) Kuhlm, found in dry fields of the semiarid region, forms dense clumps and has 2.3–5 cm inflorescences and 2.8–3.5 mm spikelets; and Mesosetum rottboellioides (Kunth) Hitchc. The species M. rottboellioides represents a new occurrence for the state of Rio Grande do Norte, recorded in the Caatinga region of the municipality of Campo Grande. This new occurrence reinforces the importance of floristic studies in little-explored biomes, reinforcing the relevance and urgency of conducting new research on the flora of Rio Grande do Norte, which is both rich in diversity and still insufficiently known.