One or More Species of Gynerium ? (Poaceae)

Abstract

Summary. Gynerium sagittatum (Aubl.) P. Beauv. is a widespread neotropical reed-like grass and a distinctive species of river banks. In early taxonomic literature it was described several times in different genera and as a result of this has acquired a lengthy synonymy. Recent findings indicate that Gynerium is highly variable in the western parts of South America, producing morphologically and ecologically distinct forms. We have studied the variation of Gynerium over all of its range, using field observations and herbarium surveys. Herbarium specimens were mostly of poor quality and appeared to be of limited value in studies of variation. Some botanists have considered Gynerium to be a single species, while others have suggested it is a species complex. We have adopted the former approach and have recognized two new varieties, described here, in the hope that they will provide a guide for future studies. A validation of the typification for Gynerium sagittatum is also provided.