Primeiro registro de ocorrência de Lemna Aequinoctialis Welw. em dois municípios do Território Vale do Sambito, semiárido brasileiro

Abstract

Lemna is a genus of freshwater aquatic herbs characterized by a thalloid body called a frond, which floats on the surface or remains slightly submerged. During botanical excursions in the Vale do Sambito, Piauí, two populations of Lemna aequinoctialis Welw. were located. This study investigated the species’ distribution and morphology in the municipalities of Elesbão Veloso and Valença do Piauí, with collections conducted in November 2023 and March 2024, respectively. The collections were carried out in three strategic water bodies, providing a comprehensive view of L. aequinoctialisoccurrence. After collection, samples were washed, fixed, stained, and analyzed in the laboratory, using photographs and comparisons with taxonomic descriptions to confirm species identification. A geographic distribution map of the species in Piauí was also created. The species was identified based on the presence of three veins in the frond and a root that can reach up to 34 mm in length, surrounded by a cylindrical winged membrane. Distinctive morphological characteristics include floating, asymmetrical, ovate to lanceolate fronds. L. aequinoctialis was found in greater abundance in Elesbão Veloso, possibly due to anthropogenic conditions, such as water damming and organic matter accumulation, which favor its growth. The analysis revealed a strong correlation between L. aequinoctialis and the water resources of the Parnaíba River basin, with inferred occurrence in other municipalities in the Valença microregion. This study contributes to understanding the species’ distribution, with implications for future research on its ecological role and biotechnological potential.