Blake's Knotweed, Leathery Knotweed: Polygonum achoreum (Synonym: Polygonum erectum ssp. achoreum) -
Alaska Wild Rhubarb: Polygonum alpinum -
Doorweed, Prostrate Doorweed: Polygonum aviculare ssp. aviculare (Synonyms: Polygonum aviculare ssp. heterophyllum, Polygonum aviculare ssp. maximum, Polygonum aviculare ssp. monspeliense, Polygonum aviculare var. aviculare, Polygonum aviculare var. littorale, Polygonum aviculare var. vegetum, Polygonum heterophyllum, Polygonum monspeliense) -
American Knotweed, Prairie Knotweed, Renouee Faux-buis: Polygonum aviculare ssp. buxiforme (Synonyms: Polygonum aviculare var. littorale, Polygonum buxiforme, Polygonum littorale) -
Common Knotweed, Oval-leaf Knotweed, Prostrate Knotweed, Yard Knotweed: Polygonum aviculare ssp. depressum (Synonyms: Polygonum aequale, Polygonum arenastrum, Polygonum aviculare ssp. aequale, Polygonum aviculare ssp. calculatum, Polygonum aviculare ssp. microspermum, Polygonum aviculare var. depressum, Polygonum calcatum, Polygonum microspermum, Polygonum montereyense) -
Common Knotweed, Narrow-leaf Knotweed, Prostrate Knotweed, Yard Knotweed: Polygonum aviculare ssp. neglectum (Synonyms: Polygonum aequale ssp. oedocarpum, Polygonum aviculare ssp. rectum, Polygonum aviculare var. angustissimum, Polygonum neglectum) -
California Knotweed: Polygonum californicum (Synonyms: Duravia californica, Polygonum greenii) -
Cascade Knotweed: Polygonum cascadense -
Douglas' Knotweed, Austin's Knotweed: Polygonum douglasii (Synonyms: Polygonum douglasii ssp. douglasii, Polygonum douglasii var. douglasii, Polygonum douglasii var. latifolium) -
Erect Knotweed: Polygonum erectum (Synonym: Polygonum aviculare var. erectum) -
Fowler's Knotweed: Polygonum fowleri ssp. fowleri (Synonym: Polygonum allocarpum) -
Palouse Knotweed, Wiry Knotweed: Polygonum majus (Synonyms: Polygonum coarctatum, Polygonum douglasii ssp. majus) -
Broadleaf Knotweed, Broad-leaved Knotweed, Leafy Dwarf Knotweed, Zigzag Knotweed: Polygonum minimum (Synonym: Polygonum torreyi) -
Nuttall's Knotweed: Polygonum nuttallii (Synonyms: Polygonum douglasii ssp. nuttallii, Polygonum intermedium) -
Beach Knotweed, Black Knotweed, Nailwort Knotweed: Polygonum paronychia -
Parry's Knotweed, Prickly Knotweed: Polygonum parryi -
Closeflowered Knotweed, Close-flowered Knotweed: Polygonum polygaloides ssp. confertiflorum (Synonyms: Polygonum confertiflorum, Polygonum imbricatum, Polygonum kelloggii var. confertiflorum, Polygonum watsonii) -
Kellogg's Knotweed, White-margined Knotweed: Polygonum polygaloides ssp. kelloggii (Synonyms: Polygonum kelloggii, Polygonum minutissimum, Polygonum unifolium) -
Pokeweed Fleeceflower, Polygala Knotweed, White-margined Knotweed: Polygonum polygaloides ssp. polygaloides (Synonym: Polygonum polygaloides var. montanum) -
Sawatch Knotweed: Polygonum sawatchense (Synonyms: Polygonum douglasii ssp. johnstonii, Polygonum douglasii var. johnstonii, Polygonum sawatchense ssp. oblivium) -
Shasta Knotweed: Polygonum shastense -
Fall Knotweed, Spury Knotweed: Polygonum spergulariaeforme (Synonyms: Polygonum douglasii ssp. spergulariiforme, Polygonum emaciatum, Polygonum spergulariaeforme) -