Polygonum pensylvanicum

Species category

Weed

Common name

Pennsylvania smartweed

Diagnostic characters

Planting unit

AcheneAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.

Shape

Compressed obovateObovate:
Inverted egg shaped with apical end the broadest.

Size

  • Length 3.2–3 mm 
  • Width 2–2.7 mm 
  • Thickness 0.5–0.6 mm 

Color

Black

Texture

Smooth or with slight roughness; shiny.

Other structures

Remnants of floral parts present. Sides are flat or convex in center.

Identification notes

AchenesAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.
are two-sided and slightly convex on each side. Shape is orbicular except for the acute point at the apexApical:
The distal end of the fruit or seed away from the point of attachment or attachment scar.
.

Noxious weed seed categories

Not listed

AOSA examination list

Not included

Nomenclature

Family

Polygonaceae

Valid name

Polygonum pensylvanicum L.

Synonyms

Persicaria bicornis (Raf.) Nieuwl.
Persicaria longistyla (Small) Small 
Persicaria mississippiensis
(Stanford) Small
Persicaria pensylvanica (L.) Small
Persicaria pensylvanica (L.) Small var. dura (Stanford) C.F. Reed
Polygonum bicorne Raf
Polygonum longistylum Small
Polygonum longistylum Small var. omissum (Greene) Stanford
Polygonum mexicanum auct. non Small
Polygonum mississippiense Stanford
Polygonum mississippiense Stanford var. interius
Polygonum pensylvanicum L
. var. durum Stanford
Polygonum pensylvanicum L. var. eglandulosum J.C. Myers
Polygonum pensylvanicum L. var. genuinum Fernald
Polygonum pensylvanicum L. var. laevigatum Fernald
Polygonum pensylvanicum L. var. rosiflorum J.B.S. Norton

 Polygonum pensylvanica.  Two-sided achenes that are slightly convex on each side. 
Polygonum pensylvanica. Two-sided achenes that are slightly convex on each side.