Esporos de espécies selecionadas de musgos (Bryophyta) de Minas Gerais: morfologia, ultraestrutura e aspectos ecológicos

Abstract

Mosses are cryptogamic land plants, included in Bryophyta and characterized by an avascular condition and the presence of leafy gametophytes (dominant life generation), with leaves spirally arranged around the stem. The growth form, together with the branching pattern, is called the life-form, which may be mat, weft, dendroid, pendant, turf and cushion. The sporophyte consists of foot, seta and capsule. The spores, dispersal units of mosses, are formed in the capsule and show a three layered sporoderm, consisting in perine, exine and intine. Studies in palynology of mosses have elucidated important issues about sporogenesis, spore germination and morphology of many species, some of them being employed in taxonomy. Observing that the data correlating morphological characteristics of the spores with the adaptive strategies of species are still rare, this work aimed to study the spores of 19 species of mosses which occur in the state of Minas Gerais and to correlate the palynological data obtained with the adaptive life strategies of species. We included in the sample a set of acrocarpous and pleurocarpous mosses which occur on different substrates and show with different life-forms. For the palynological study, the spores were observed untreated or submitted to the acetolysis method, under light microscope and scanning electron microscope. After we obtained the data concerning to the palynological analysis and the adaptative strategies of species, the information was included in a binary matrix and through the PAST 15.2 software, a cluster analysis was performed. The palynological results show three distinct patterns of perine ornamentation: granular formed by individual granules, granular formed by compounded granules and baculated. The ornamentation observed in spores of Weissia controversa was first described. Leptodontium viticulosoides showed anisomorphic spores. Cluster analysis revealed a relationship between acrocarpous species, the occupation of the substrate concrete and the presence of a thick wall in sporoderm.