Aspectos morfo-anatômicos de Marsilea deflexa A. Braun, uma contribuição taxonômica

Abstract

The Marsileaceae family presents two genera (Regnellidium and Marsílea), this presents about 60 species of which Marsílea deflexa will be A. Braun studied. However, there are few anatomical studies developed on the species. In view of this, this work aims to study this species, with the purpose of morpho-anatomically studying the vegetative organs for a taxonomic contribution. The samples were collected in the district of Icoarací-Pa and compared to the exsiccates of the MG herbarium and submitted to the usual techniques of the plant anatomy laboratory. Morphologically, the species has leaves composed of 4 obovate leaflets symmetrically arranged in the shape of a cross, which vary from 2 cm long when in saturated soil and 2.5 long when in flooded areas as floating or emergent. These leaflets are curled when young. The pedicel is cylindrical approximately 17 cm tall in saturated soil and 22 cm tall in flooded areas and has a curvature at the apex and when fertile the three sporocarps inserted at the base. The stem is stoloniferous, creeping or floating emitting three roots at each node and one at the internode. In frontal view, the epidermal cells are heterodimensional with sinuous walls, elongating when arranged longitudinally to the axis of the veins and covered by a smooth cuticle interrupted by striations near the stomata. The species is amphistomatic and presents paradtic, anomodotic and diadtic type stomas. In cross section, the mesophyll presents palisade parenchyma formed by a layer of cells with evident substomatic chambers and the lacunate parenchyma by 2 to 4 layers of irregular cells that divide large air gaps, forming the so-called aeriferous parenchyma. The vascular bundles are distributed in the lacunose parenchyma and wrapped apparently by an endodermis. The pedolus presents uniseriate epidermis, peripheral cortical region formed by aeriferous lacunae with large diaphragms. and the innermost by parenchyma and endodermis with evident Caspary striae. The central vascular tissue is surrounded by a thickened pericycle. The root in cross section of the proximal region is formed by an apparently uniseriate epidermis, presenting six layers of isodiametric cortinal cells with centralized vascular tissue.