A taxonomic review of the genus Zoysia has not been made since its designation in 1801. In the past 200 years, most regions of the world have been surveyed for their grass flora. As a result, a more resolved image of indigenous Zoysia distributions has emerged. Univariate and multivariate analyses of morphological data from 400 specimens representative of the global distribution will be presented as evidence supporting the taxonomic treatment. A similar evaluation of nuclear DNA RFLP fingerprints from representative accessions of the seven Zoysia species present in the TAES-Dallas Zoysia germplasm collection will also be presented. Eleven morphospecies were recognized in this taxonomic study. Morphologically the species were bounded by differences in a combination of traits, both floral and vegetative. Nine floral traits were important in distinguishing among the species, including spikelet length, width and shape, and number of spikelets per raceme. Floral traits alone gave good resolution among most species, although boundaries were not succinct between Z. pacifica and Z. matrella, nor between Z. macrantha and Z. japonica. Only six species could be recognized by vegetative traits alone. Important among the vegetative traits were diameter of rolled blades and presence of elongated culm internodes. RFLP fingerprints supported the boundaries of the seven species examined. Fingerprints provided preliminary evidence of a continuum of interspecific hybrids between Z. matrella, Z. japonica, and Z. pacifica. Future study of the co-occurrence and genetic structure of Z. matrella, Z. pacifica, and hybrid populations is needed to support the existence of these hybrids.

Key words: Morphological variation,Poaceae,Taxonomic review,Zoysia