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Wisconsin Plant of the Week

Polygonum punctatum Ell.

Polygonaceae (Smartweed Family)

Common Name:

dotted smartweed

08/23/1999

Dotted smartweed is an annual or perennial native herb.  It grows to 0.5 m tall in moist ground, shallow water and marshes.  It's often found in more shady areas than other smartweeds. The leaves have a very sharp peppery taste, often somewhat delayed.

As in all smartweeds, the nodes on the stem are swollen and each leaf forms a sheath around the stem called an "ochrea."  The ochrea extends up the stem from the node where the leaf is attached.  Most smartweeds require mature fruit to identify the species.

Leaves are alternate and lance-shaped up to 20 cm long with smooth margins.  The stems and leaves are smooth.

Small white flowers bloom through August and September.  The inflorescence is an erect raceme but the flowers have irregular spaces between them.  The base of each flower has yellow glandular dots visible with a lens.

Dotted Smartweed is similar to False Water Pepper (P. hydropiperoides) which lacks the pepper taste, and to Water Pepper (P. hydropiper) which is peppery, but whose racemes are continuous rather than interrupted, and has greenish flowers.

  • Origin of the name: Polygonum:  Gr. polys, many; Gr. gony, knee; refers to the swollen nodes or "many joints"
    punctatum:  L., punctum, a point; refers to the dotted tepals
  • Range:  Que. to BC, s. to S. Amer.
  • WI Range:  Statewide
  • Common associates: Rice cut grass, bluejoint grass, arrowhead
  • Wetland Indicator Status: OBL
  • Coefficient of Conservatism:  C = 6 (S&W) C = 5 (MI)
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