The lopseed (Phryma leptostachya var. asiatica) belongs to Verbenaceae (the Verbena family). It is a perennial herb that is distributed all over Japan, the Korean Peninsula, China, as far as the Himalayas, and eastern North America separately. It is the only species in the genus. This herb grows in the shady places of forest floors and edges, and can reach 30-70 cm in height. The leaves are ovate and opposite with serrated edges. The long flowring stalks are borne and the pale pink flowers bloom sparsely from June to August. These roots was used for flypaper after extract by boiling in former days.