Paspalum L. is a large genus of C4 grasses with about 400 species that are native to predominantly tropical and subtropical regions. The center of diversity is in South America. Only a few species have been developed commercially for use as pasture, forage, or turf. There have been a few breeding programs. The genus has a very high frequency of species with sexual diploid and apomictic polyploid biotypes that form agamic complexes. Great evolutionary power is generated by the occurrence of occasional sexual hybridization followed by fixation of successful polyploid genotypes by apomixis. Better understanding of this system should lead to considerable advances being made in plant breeding. In this context, collection and conservation of the sexual diploid Paspalum species requires priority action as these species will provide the engine for the generation of new genetic diversity.