Abstract -- Resumen -- Introduction -- Material and Methods -- History of the genus -- Morphology -- Habit, sheaths, ligules and blades -- Inflorescences Spikelets -- Texture and ornamentation of the upper anthecium -- Foliar anatomy -- Chromosome numbers -- Phylogeny and evolution -- Geographic distribution -- Taxonomic treatment -- Key of sections and ungrouped species.-Species -- Excluded species -- Acknowledgments -- List of taxa -- Literature cited -- List of exsicatta -- Index of local names -- Index of scientific names.