What is Persicaria?
{{italictitle}} {{Automatic taxobox |image = Persicaria capitata AF crop.jpg |image_caption = ''[[Persicaria capitata]]'' |taxon = Persicaria |authority = [[Philip Miller|Mill.]] 1754 |subdivision_ranks = Species |subdivision = |synonyms_ref=<ref>{{cite web |url=http://www.plantsoftheworldonline.org/taxon/urn:lsid:ipni.org:names:60433517-2#synonyms |title=''Persicaria'' Mill. |author=<!--Not stated--> |date=2017 |website=Plants of the World Online |publisher=Board of Trustees of the Royal Botanic Gardens, Kew |access-date=17 September 2020}}</ref> |synonyms={{collapsible list| *''Amblygonum'' <small>Rchb.</small> *''Antenoron'' <small>Raf.</small> *''Cephalophilon'' <small>(Meisn.) Spach</small> *''Chylocalyx'' <small>Hassk.</small> *''Echinocaulon'' <small>(Meisn.) Spach</small> *''Echinocaulos'' <small>Hassk.</small> *''Goniaticum'' <small>Stokes</small> *''Heptarina'' <small>Raf.</small> *''Lagunaea'' <small>C.Agardh</small> *''Lagunea'' <small>Lour.</small> *''Mitesia'' <small>Raf.</small> *''Peutalis'' <small>Raf.</small> *''Pogalis'' <small>Raf.</small> *''Sunania'' <small>Raf.</small> *''Tasoba'' <small>Raf.</small> *''Tovara'' <small>Adans.</small> *''Tracaulon'' <small>Raf.</small> *''Truellum'' <small>Houtt.</small> }}}} '''''Persicaria''''' is a [[genus]] of [[herbaceous]] [[flowering plants]] in the knotweed family, Polygonaceae. Plants of the genus are known commonly as knotweeds.<ref name=Stace>{{cite book|last=Stace|first=C.A.|year=2010|title=New Flora of the British Isles|url=https://archive.org/details/newflorabritishi00stac|edition=Third|publisher=Cambridge University Press|location = Cambridge, U.K.| page=[https://archive.org/details/newflorabritishi00stac/page/88 88]|isbn=9780521707725}}</ref>{{rp|436}} or '''smartweeds'''.<ref name=fna>[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=124629 ''Persicaria''.] Flora of North America.</ref> It has a [[cosmopolitan distribution]], with species occurring nearly worldwide.<ref name=fna/><ref name=nsw>[http://plantnet.rbgsyd.nsw.gov.au/cg