[The Genus Polygonum East of the Cascades of Oregon and Washington]

American Bistort, Snakeweed, Mountain Meadow Knotweed, Western Bistort

Bistorta bistortoides

Synonyms: Persicaria bistortoides, Polygonum bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium, Polygonum cephalophorum, Polygonum glastifolium, Polygonum vulcanicum

American Bistort, Snakeweed, Mountain Meadow Knotweed, Western Bistort: Bistorta bistortoides (Synonyms: Persicaria bistortoides, Polygonum bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium, Polygonum cephalophorum, Polygonum glastifolium, Polygonum vulcanicum)

American bistort blooming along FS Road #27 in Thompson Valley, Fremont National Forest.......May 19, 2016.

Characteristics:

American bistort is an erect perennial arising 30-60 cm from a thick tuber. The basal leaves are long petiolate and not jointed to the stem. The leaf blade is oblong-lanceolate or wider, to 15 cm long. The stipules are brownish and 3-6 cm long. There are a few lanceolate stem leaves, reduced in size upwards on the stem. The inflorescence is a terminal raceme, spike-like, from 3-6 cm longand 1-2 cm wide. It is densely white-flowered as seen in the photo above.


Habitat:

American bistort is a montane species found in moist or swampy meadows, streambanks, or alpine slopes.


Range:

American bistort is found from southern Alaska to southern California, east to Alberta, Montana, and New Mexico.


American Bistort, Snakeweed, Mountain Meadow Knotweed, Western Bistort: Bistorta bistortoides (Synonyms: Persicaria bistortoides, Polygonum bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium, Polygonum cephalophorum, Polygonum glastifolium, Polygonum vulcanicum) - American Bistort, Snakeweed, Mountain Meadow Knotweed, Western Bistort: Bistorta bistortoides (Synonyms: Persicaria bistortoides, Polygonum bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium, Polygonum cephalophorum, Polygonum glastifolium, Polygonum vulcanicum)

American bistort blooming along a small creek along the South Loop Road about one mile downhill from the East Rim Viewpoint, Steens Mountain, Harney County, Oregon........August 31, 2011.

Inflorescence of American Bistort, Snakeweed, Mountain Meadow Knotweed, Western Bistort: Bistorta bistortoides (Synonyms: Persicaria bistortoides, Polygonum bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium, Polygonum cephalophorum, Polygonum glastifolium, Polygonum vulcanicum)
The photo above shows a close-up of the inflorescence of american bistort as seen on moist grassland slopes in Zumwalt Prairie between Buckhorn Lookout and Enterprise, OR........June 27, 2008.

Inflorescence of American Bistort, Snakeweed, Mountain Meadow Knotweed, Western Bistort: Bistorta bistortoides (Synonyms: Persicaria bistortoides, Polygonum bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium, Polygonum cephalophorum, Polygonum glastifolium, Polygonum vulcanicum) - American Bistort, Snakeweed, Mountain Meadow Knotweed, Western Bistort: Bistorta bistortoides (Synonyms: Persicaria bistortoides, Polygonum bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium, Polygonum cephalophorum, Polygonum glastifolium, Polygonum vulcanicum) - Basal leaves of American Bistort, Snakeweed, Mountain Meadow Knotweed, Western Bistort: Bistorta bistortoides (Synonyms: Persicaria bistortoides, Polygonum bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium, Polygonum cephalophorum, Polygonum glastifolium, Polygonum vulcanicum)

American bistort as seen at the north trailhead for Baldy Mountain, Malheur National Forest........July 1, 2010.

A wet meadow full of American Bistort, Snakeweed, Mountain Meadow Knotweed, Western Bistort: Bistorta bistortoides (Synonyms: Persicaria bistortoides, Polygonum bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium, Polygonum cephalophorum, Polygonum glastifolium, Polygonum vulcanicum) as seen on the Steens Mountain, Harney County, Oregon. - American Bistort, Snakeweed, Mountain Meadow Knotweed, Western Bistort: Bistorta bistortoides (Synonyms: Persicaria bistortoides, Polygonum bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium, Polygonum cephalophorum, Polygonum glastifolium, Polygonum vulcanicum)

A wet meadow full of american bistort as seen about one mile downhill from the Kiger Gorge Overlook, Steens Mountain, Harney County, Oregon........August 31, 2011. The photo at right shows a late blooming american bistort as seen in wet riparian meadows along the South Loop Road about one mile west of the East Rim Viewpoint, Steens Mountain..........September 20, 2015.

Inflorescence of American Bistort, Snakeweed, Mountain Meadow Knotweed, Western Bistort: Bistorta bistortoides (Synonyms: Persicaria bistortoides, Polygonum bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium, Polygonum cephalophorum, Polygonum glastifolium, Polygonum vulcanicum)


Paul Slichter