ANDERSON, SHARON J. Tracy Herbarium, Department of Rangeland Ecology and Management, Texas A&M University, College Station, TX 77843. - Taxonomy of Zoysia (Poaceae): morphological and molecular variation.
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