| This is a revision of the genus Zoysia emphasizing morphological variation, primarily florid. A review of the genus Zoysia has not been made since its description in 1801. Because most regions of the world have been surveyed for their grass flora, with the exceptions of equatorial Melanesia and South America, a more resolved image of indigenous Zoysia distributions has emerged.; Eleven species are recognized in this study, with the indigenous distribution extending from 42°N to 42°S in the coastal to near-coastal areas of East and Southeast Asia, to the northern coast of Tasmania and the South Island of New Zealand, and along the eastern coasts of India and Australia. Also included in the distribution are the many atolls and islands of the Indian and Pacific Oceans, as far east as Rapa and west as Mauritius. Zoysia has been introduced to many of the remaining continents as a turfgrass. Reports were found of Z. matrella growing in Madagascar, the west coast of South America, and in much of the United States. No single species has been reported as the sole species in a geographic realm such as the islands of the Philippines.; Morphologically the species were delimited by differences in a combination of traits, both floral and vegetative. Floral traits important in distinguishing among the species were peduncle diameter, raceme length, number of spikelets per raceme, pedicel apex shape, fusion of glume to pedicel, glume texture, and spikelet length, width and shape. Floral traits alone gave good resolution among most species, although boundaries were not distinct between Z. pacifica and Z. matrella, nor between Z. macrantha and Z. japonica. Only six species could be recognized by vegetative traits alone. Important vegetative traits were presence of blade unrolling, blade diameter and/or width, collar length, culm elongated internode diameter, 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. pacific. Study of the co-occurrence and genetic structure of Z. matrella, Z. pacifica, and hybrid populations is required to verify the existence of these hybrids. |
