American Bistort, Mountain Meadow Knotweed, Snakeweed: Bistorta bistortoides (Synonym: Polygonum bistortoides) -
Black Bindweed, Climbing Bindweed, Ivy Bindweed, Wild Buckwheat: Fallopia convolvulus (Synonyms: Bilderdykia convolvulus, Fallopia convolvulus var. subulata, Polygonum convolvulus, Polygonum convolvulus var. convolvulus, Reynoutria convolvulus, Tinaria convolvulus) -
Bohemian Knotweed: Fallopia x bohemica (Synonyms: Polygonum x bohemicum, Polygonum cuspidatum x sachalinense) -
Japanese Knotweed: Fallopia japonica (Synonyms: Fallopia japonica, Polygonum cuspidatum, Reynoutria japonica) -
Giant Knotweed: Fallopia sachalinensis (Synonyms: Polygonum sachalinense, Reynoutria sachalinensis, Tiniaria sachalinensis) -
Water Smartweed: Persicaria amphibia (Synonyms: Polygonum amphibium, Polygonum amphibium var. coccineum, Polygonum amphibium var. emersum, Polygonum amphibium var. natans, Polygonum amphibium var. stipulaceum, Polygonum coccineum, Polygonum coccineum var. coccineum, Polygonum coccineum var. hartwrightii, Polygonum natans, Polygonum natans var. hartwrightii) -
Smartweed, Marshpepper Smartweed: Persicaria hydropiper (Synonym: Polygonum hydropiper) -
Swamp Smartweed, Waterpepper, Water Pepper: Persicaria hydropiperoides (Synonyms: Persicaria paludicola, Polygonum hydropiperoides, Polygonum hydropiperoides var. adenocalyx, Polygonum hydropiperoides var. asperifolium, Polygonum hydropiperoides var. buschianum, Polygonum hydropiperoides var. digitatum, Polygonum hydropiperoides var. hydropiperoides, Polygonum hydropiperoides var. opelousanum, Polygonum hydropiperoides var. psilostachyum, Polygonum opelousanum, Polygonum opelousanum var. adnocalyx, Polygonum persicarioides) -
Pale Smartweed, Willow Weed: Persicaria lapathifolia (Synonyms: Polygonum incarnatum, Polygonum lapathifolium, Polygonum lapathifolium var. salicifolium, Polygoum linicola, Polygonum nodosum, Polygonum scabrum, Polygonum tomentosum) -
Heartweed, Redshank, Spotted Ladysthumb, Spotted Lady's-thumb: Persicaria maculosa (Synonym: Polygonum persicaria) -
Pennsylvania Smartweed, Pinkweed: Persicaria pensylvanica (Synonyms: Persicaria bicornis, Persicaria longistyla, Persicaria mississippiensis, Persicaria pensylvanica var. dura, Polygonum bicorne, Polygonum longistylum, Polygonum longistylum var. omissum, Polygonum mexicanum, Polygonum mississippiense, Polygonum mississippiense var. interius, Polygonum pensylvancium var. durum, Polygonum pensylvanicum var. eglandulosum, Polygonum pensylvanicum var. genuinum, Polygonum pensylvanicum var. laevigatum, Polygonum pensylvanicum var. rosiflorum) -
Water Smartweed, Dotted Smartweed: Persicaria punctata (Synonyms: Polygonum punctatum, Polygonum punctatum var. punctatum) -
Common Knotweed, Doorweed, Oval-leaf Knotweed, Prostrate Knotweed, Yard Knotweed: Polygonum aviculare ssp. depressum (Synonym: Polygonum arenastrum) -
California Knotweed: Polygonum californicum (Synonym: Polygonum greenii) -
Cascades Polygonum: Polygonum cascadense -
Douglas' Knotweed: Polygonum douglasii (Synonyms: Polygonum douglasii ssp. douglasii, Polygonum douglasii var. douglasii, Polygonum douglasii var. latifolium, Polygonum montanum) -
Wiry Knotweed, Palouse Knotweed: Polygonum majus (Synonyms: Polygonum coarctatum var. majus, Polygonum douglasii ssp. majus) -
Broadleaf Knotweed, Broad-leaved Knotweed, Leafy Dwarf Knotweed, Zigzag Knotweed: Polygonum minimum (Synonym: Polygonum torreyi) -
Nuttall's Knotweed: Polygonum nuttallii (Synonym: Polygonum douglasii ssp. nuttallii) -
Closeflowered Knotweed: Polygonum polygaloides ssp. confertiflorum (Synonyms: Polygonum confertiflorum, Polygonum imbricatum, Polygonum kelloggii var. confertiflorum, Polygonum watsonii) -
Kellogg's Knotweed: Polygonum polygaloides ssp. kelloggii (Synonyms: Polygonum kelloggii, Polygonum minutissimum, Polygonum unifolium) -
Milkweed Knotweed, Pokeweed Fleeceflower, White-margined Knotweed: Polygonum polygaloides ssp. polygaloides (Synonym: Polygonum polygaloides var. montanum) -
Bushy Knotweed, Yellow-flowered Knotweed: Polygonum ramosissimum ssp. ramosissimum
Sawatch Knotweed: Polygonum sawatchense ssp. sawatchense ? -
Autumn Knotweed, Fall Knotweed, Spurry Knotweed: Polygonum spergulariaeforme (Synonyms: Polygonum douglasii ssp. spergulariiforme, Polygonum emaciatum) -