The other species in the genus Polygonum:

Polygonum bistorta / Ibukitoranoo
Polygonum caespitosum var. laxiflorum / Hanatade
Polygonum conspicuum / Sakuratade
Polygonum cuspidatum / Itadori
Polygonum debile / Miyamatanisoba
Polygonum filiforme / Mizuhiki
Polygonum filiforme f. albiflorum / Ginmizuhiki
Polygonum polyneuron / Akinomichiyanagi
Polygonum hydropiper / Yanagitade
Polygonum japonicum / Shirobanasakuratade
Polygonum lapathifolium / Ooinutade
Polygonum longisetum /  Inutade

Polygonum hydropiper / Yanagitade