It includes a number of plants that can be highly invasive, such as Japanese knotweed, Reynoutria japonica, and its hybrid with R. sachalinensis, R. × bohemica.

[1] A 2015 molecular phylogenetic study suggested that the genera and tribes in Polygonoideae were related as shown in the following cladogram.

[1] Oxygoneae (Oxygonum) Persicarieae (Bistorta, Koenigia, Persicaria) Fagopyreae (Fagopyrum) Pteroxygoneae (Pteroxygonum + some Fallopia) Calligoneae (Calligonum, Pteropyrum) Rumiceae (Oxyria, Rheum, Rumex) Polygoneae (Atraphaxis, Duma, Fallopia, Knorringia, Muehlenbeckia, Polygonum, Reynoutria) Rumex included Emex, and Fallopia was not monophyletic, with some species placed outside the main group in the tribe Polygoneae, and some others grouping with Pteroxygonum, placed in the tribe Pteroxygoneae.

[1] A 2011 classification divided the subfamily into five tribes, Calligoneae, Fagopyreae, Persicariae, Polygoneae and Rumiceae, leaving some genera unplaced.

[1] Many species in the subfamily have at one time or another been placed in different genera; for example the invasive Japanese knotweed is currently in the genus Reynoutria, but has been in Polygonum and Fallopia.