Taxonomic features of species of Panicum section Parviglumia are reviewed and compared with those of other taxa in tribe Paniceae. The new genus Morronea, including six species ranging from Mexico to Argentina, is proposed on the basis of morphological and molecular characters. They are plants growing at forest edges, with membranous-ciliate ligules, lower glume reduced, 1/6 to 1/4 the spikelet length, lower palea and lower flower absent, and upper anthecium indurate with simple papillae and conspicuous macrohairs all over its surface. The new combinations: Morronea arundinariae, M. cayoensis, M. guatemalensis, M. incumbens, M. parviglumis, and M. trichidiachnis are proposed and the new genus is compared with other genera of the tribe Paniceae.