Pollen wall development in Malvastrum corchorifolium (Malvaceae)

The Malvaceae family has many species that are the subject of systematic controversy. Its broad spectrum of fruit and pollen morphology has challenged taxonomists because often morphological studies lead to different conclusions. Therefore, this study of selected stages of pollen wall development in Malvastrum corchorifolium is offered as another approach to verify its current taxonomic assignment and assist in the clarification of malvacean ancestry. Aperture number, endexine thickness and the presence of basal cushions are features that concur with its present placement in the Abutileae tribe, Sidinae subtribe and genus Malvastrum. Its advanced spine morphology, long spines with pointed apices and prominent basal cushions, suggest that Malvastrum corchorifolium is highly specialized and evolutionarily advanced.