Synonyms: Polygonum coarctatum var. majus, Polygonum douglasii ssp. majus
The photo above shows the inflorescence of wiry knotweed as seen from a sandy to rocky soils at Horsethief Butte to the northeast of The Dalles, OR................October 7, 2006.
Wiry knotweed is an upright annual with simple to branched stems afrom 10-30 cm tall. The stems are strongly angled, and the numerous leaves are found on the stems. The leaves are linear to oblong, mostly 2-5 cm long and 2-7 mm wide, sessile, and reduced in size upwards on the stem. The stipules are 10-15 mm long.
The flowers are mostly paired in the elongate racemes. They are in the axils of the upper, reduced bracts. The flowers are about 4-5 mm long, greenish-white with white or pink margins. There are 8 stamens, with puple anthers.
Wiry knotweed may be found on dry gravelly or heavy soils from the sagebrush desert to mountainous ponderosa forests.
Wiry knotweed may be found east of the Cascade Mts. from northern Washington south to northern California, and east to Idaho and western Montana.
In the Columbia River Gorge, it may be found from east of Mosier, OR to the eastern end of the gorge. It may be found there between the elevations of 100'-600'.