In order to investigate the taxonomic value of a number of characters in the elucidation of relationships within the collective genus Polygonum L., and segregate genera Atraphaxis L., Calligonum L., Pteropyrum Jaub. & Spach., Oxygonum Burch., Fagopyrum Mill., Harpagocarpus Hutch. & Dandy and Polygonella Michx., 83 species of the tribe Polygoneae emend. Jaretzky were studied. The following floral characters were examined: stamen number, insertion and external morphology; structure and morphology of the floral nectaries; vasculature and surface morphology of the tepals.
Problems in floral morphology in Polygonaceae are discussed, together with relationships within the Family. The tribal division proposed by Haraldson (1978) is supported, but a new and different delimitation of genera is proposed. The present data support a division of Polygonum L. sensu lato and its related taxa into two tribes: Polygoneae (containing Polygonum L. sensu stricto, Fallopia Adans., Oxygonum Burch., Pteropyrum Jaub. & Sparh., Atraphaxis L. and Calligonum L.), and Persicarieae (containing Fagopyrum Mill., Harpagocarpus Hutch. & Dandy, Persicaria Mill. and Koenigia L.). The genus Reynoutria Houtt. is included as a section of Fallopia Adans.; Bislorta Mill., Aconogonon Reichenb. and Tovara Adans. are included within Persicaria Mill.
A number of new combinations are proposed in Persicaria and Fallopia.