In Korea, two species of Ho-chang-Ho-chang $(Polygonum;cuspidatum ;S_{IEB}.;et;Z_{UCC}.)$ and Wang-Ho-chang $(Polygonum ;sachalinense;F_R.;S_{CHM}.)$-had been identified, but the components of the leaves of Polygonum species growing in Korea had never been reported. The authors examined the anatomical characteristics of Korean Polygonum species, identified the flavonoids contained in their leaves and obtained the following results: Korean Polygonum species should be divided into three species: $Polygonum;cuspidatum;S_{IEB}.;et;Z_{UCC}.,;P. ;sachalinense;F_R.;S_{CHM};and;P.;elliptica;M_{IGO}$. The last one was illustrated in the report. P. cuspidatum contained reynoutrin and quercitrin, but no isoquercitrin could be identified. P. sachalinense also contained both reynoutrin and quercitrin. P. elliptica, which had never been studied, included the same flavonoids.