Northern Prairie Wildlife Research Center
Aquatic and Wetland Vascular Plants of the Northern Great Plains
15. Polygonaceae, the Smartweed Family
1. Polygonum L. -- Smartweed, knotweed, tear-thumb
8. Polygonum persicaria L.-- Lady's thumb
Erect to spreading, simple to branched annual 2-8 dm tall, the stems often reddish.
Leaf blades lanceolate to elliptic-lanceolate, 3-15 cm long, 0.5-3 cm
wide, glabrous to sparsely strigose, usually puncticulate, especially beneath,
acute to long-acuminate, cuneate at the base, subsessile or on petioles to 1
cm long; ocreae 5-15 mm long, fringed with bristles, glabrous to strigose.
Racemes usually few to many, globose to cylindric, 0.5-2.5 cm long, 0.5-1
cm thick. Flowers light to deep pink; calyx 2.5-3 mm long, 5-lobed to
near the middle; stamens 6, included; style branches 2 or 3. Achenes
black, shiny, lenticular or some often trigonous, 2-2.5 mm long. Jul--Sep. Springs,
shores, stream banks and ditches, where water is fresh; occasional, most common
in the e part; (Intro. from Europe and now throughout N.Amer.).
Previous Species -- Polygonum pensylvanicum
L.-- Pennsylvania smartweed
Return to Family -- Polygonaceae -
The Smartweed Family
Next Species -- Polygonum punctatum Ell.--