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Smartweed or Knotweed

Polygonum sp.

Family: Polygonaceae

  • Found in a variety of places
  • Most species like wet habitats, including roadsides and ditches
Smartweed plants
  • 46 species in the genus Polygonum in northeastern North America
  • Specific species are hard to tell apart, but can be broadly classified into two categories: Smartweeds (in which the flowers are in spike-like terminal clusters) or Knotweeds (in which the flowers are clustered in the leaf axils)
  • Vary in size by species
  • Simple leaves
  • Polygonum are identifiable by a thicker section on the stem at each leaf joint
  • Leaf base forms a kind of sheath over stem where they join
  • June-November, depending on species
  • Most are pink or white, although there are some green
  • Tight terminal clusters of tiny flowers (smartweeds) or smaller clusters nested in leaf axils (knotweeds)
Smartweed flower Smartweed leaf

Leaves can be used to make a dye.

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