Northern Prairie Wildlife Research Center


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

Western Wetland Flora

Field Office Guide to Plant Species

American Bistort
Polygonum bistortoides Pursh

JPG -- Species Photo JPG -- Distribution Map

Family: Smartweed (Polygonaceae)
Flowering: May-August
Field Marks: American bistort differs from all other species of Polygonum by its long-stalked basal leaves, its unbranched stem, and its thick, solitary, spike-like raceme.
Habitat: Along streams, in wet meadows, particularly in the mountains.
Habit: Perennial herb from a thick, fleshy rootstock.
Stems: Upright, unbranched, up to 1 1/2 feet tall, smooth.
Leaves: Basal and alternate, smooth, without teeth, the lowermost oblong to oblanceolate, pointed or rounded at the tip, up to 10 inches long, up to 2 inches wide, on stalks up to 8 inches long; uppermost leaves similar but sessile.
Flowers: Many crowded into a terminal, solitary, cylindrical, spike-like raceme; raceme up to 3 inches long, up to 3/4 inch wide; flower stalk 1/8-1/3 inch long.
Sepals: 5, united at the base, pink or white, petal-like, up to 1/4 inch long.
Petals: 0.
Stamens: Usually 5-9, exserted beyond the sepals.
Pistils: Ovary superior.
Fruits: Achenes triangular, pale brown, smooth, shiny, up to 1/6 inch long.

Previous Species -- Arrow-weed (Pluchea sericea )
Return to Species List -- Group 8
Next Species -- Willow-weed (Polygonum lapathifolium)

Accessibility FOIA Privacy Policies and Notices

U.S. Department of the Interior | U.S. Geological Survey
URL: http://www.npwrc.usgs.gov/resource/plants/florawe/species/8/polybist.htm
Page Contact Information: Webmaster
Page Last Modified: Saturday, 02-Feb-2013 06:28:19 EST
Sioux Falls, SD [sdww55]