This widespread variable tetraploid (2n = 40-44) ranges across much of North America and extends south to Brazil (FNA 5). Several varieties have been proposed, but some recent treatments have not considered these distinct enough to recognize (FNA 5); see also notes under robustior. Most colls. from Ky. have been referred to var. confertifolium (Meis.) Fassett, within Polygonum, but further study is needed. The typical variety has been reported from CALL, HICK and MERC (M); it may be distinguished (Cr) by its rhizomatous habit (versus mostly annual), inflorescences less interrupted and terminating branches (versus often interrupted and branching from lower nodes), and achenes mostly trigonous (versus lenticular). The potential for confusion or intergradation of typical punctatum with P. hydropiperoides (especially var. opelousanum) also needs further investigation. There has been much medicinal use of punctata (sensu lato) by native people in North and South America (Moerman 1998), but relatively little scientific investigation of its chemistry (e.g. Alves et al. 2001). It has an acrid peppery taste like hydropiper; no other Persicaria species in North America are known to taste as strong as this.