The Polygoneae of Eastern Asis

During five years of botanical work in China the writer felt keenly the lack of literature to assist in the satisfactory study of Chinese plants. This need was most often experienced in connection with certain large groups of closely related species within which it was difficult if not impossible to distinguish the component parts. Among these the genus Polygonum was of outstanding difficulty and was notorious in the writer's taxonomic experience because of the large proportion of unnamed specimens encountered in herbaria and the nncertainity of the determinations of those which were named. Dr. E. D. Merrill, who has had wide experience in the identification of plants from that region, assured the writer that Polygonum was, in his opinion, one of the groups most troublesome to the systematic botanist in temperate and subtropical eastern Asia. From such personal experience, and in anticipation of opportunities to come, the writer prepared a keyed enumeration of the Chinese species of Polygonum during the first year of his graduate study at the Gray Herbarium. From this early study it was apparent that the very considerable mass of literature published on this group at various times and by numerous authors was greatly in need of correlation. Furthermore, it appeared necessary to carry on studies through which the variable and complex species of this assemblage could be contrasted with and distinguished from one another. To introduce a degree of order where there has been great confusion resulting from unrelated efforts, rather than to record any considerable number of species and varieties new^ to science, has been the chief objective of this study.