USGS - science for a changing world

Northern Prairie Wildlife Research Center

  Home About NPWRC Our Science Staff Employment Contacts Common Questions About the Site

Aquatic and Wetland Vascular Plants of the Northern Great Plains

15. Polygonaceae, the Smartweed Family

1. Polygonum L. -- Smartweed, knotweed, tear-thumb

9. Polygonum punctatum Ell.-- Water smartweed

Simple to branched, erect to spreading annual 3-10 dm tall. Leaf blades lanceolate, 4-10 cm long, 1-2 cm wide, glabrous except for the minutely strigose margin, usually puncticulate, especially beneath, acute or acuminate to the blunt tip, cuneate to the short-petioled base; ocreae 5-15 mm long, fringed with bristles, glabrous to strigose. Racemes usually many, slender, elongate, loosely flowered, interrupted in the lower portion, to 10 cm long. Flowers greenish-white; calyx 3-4 mm long, strongly glandular-punctate, 5-parted to about the middle; stamens 6-8, included; style branches 2-3. Achenes dark brown to black, shiny, lenticular or trigonous, 2-3 mm long. Aug--Sep. Shores and stream banks; uncommon in s ND to frequent in NE; (Throughout most of N.Amer., s to S.Amer.).
GIF- Distribution Map

Map key

Previous Species -- Polygonum persicaria L.-- Lady's thumb
Return to Family -- Polygonaceae - The Smartweed Family
Next Species -- Polygonum ramosissimum Michx.-- Bushy knotweed

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo logo U.S. Department of the Interior | U.S. Geological Survey
Page Contact Information: Webmaster
Page Last Modified: Saturday, 02-Feb-2013 06:45:48 EST
Sioux Falls, SD [sdww54]