Curlytop Knotweed Persicaria lapathifolia (Linnaeus) S.F. Gray  Synonyms: Polygonum incarnatum, Polygonum lapathifolium.


Curlytop Knotweed is one of our more common native plants in the genus Persicaria. It is very similar to the non-native Far-eastern Smartweed (Persicaria extremiorientalis). Great care needs to be taken when trying to identify both species. Robert Naczi says the best way to identify these two species is to examine the tepals, "If I know it's either Persicaria lapathifolia or Persicaria extremiorientalis, I find it easiest to examine the tepals. Those of Persicaria lapathifolia have upside-down anchors. Each main vein splits into two arches that recurve forming a pattern like an inverted anchor. These veins are the single best diagnostic character of Periscaria lapathifolia. Persicaria extremiorientalis, on the other hand, lacks "anchor veins."

There are 44 records in the project database.

View species at Maryland Plant Atlas

View Norton-Brown Herbarium specimens

Search Google Images

Curlytop Knotweed in Washington Co., Maryland (9/13/2015). Photo by Jim Stasz. (MBP list)

Curlytop Knotweed in Allegany Co., Maryland (9/27/2014). Photo by Jim Brighton. (MBP list)

Curlytop Knotweed in Wicomico Co., Maryland (9/22/2017). Photo by Wayne Longbottom. (MBP list)

Curlytop Knotweed in Caroline Co., Maryland (9/24/2017). Photo by Wayne Longbottom. (MBP list)

Curlytop Knotweed in Prince George's Co., Maryland (8/30/2017). Photo by Bill Harms. (MBP list)

Curlytop Knotweed in Somerset Co., Maryland (9/12/2017). Photo by Wayne Longbottom. (MBP list)

View All Images

Use of images featured on Maryland Biodiversity Project is only permitted with express permission of the photographer.

View Bibliography