cultivated knotweed
(Persicaria wallichii Greuter & Burdet)

Overview

Appearance

Persicaria wallichii is a perennial plant that can grow from 23.6-78.7 in. (60-200 cm) tall.

Foliage

Leaves are alternate or basal, oval to lanceolate in shape, moderately hairy, and 3.9-7.9 in. (10-20 cm) long with heart shaped bases and pointed tips.

Flowers

Flowers are white to pink, 0.12-0.2 in. (3-5 mm) long, fragrant, and found in clusters from 7.9-13.8 in. (20-35 cm) long. Flowers bloom from mid summer to late fall.

Fruit

Seeds are dark brown in color, ovoid, 3 angled, smooth, and 0.04-0.08 in. (1-2 mm) long. They are transported mostly by water and wind.

Ecological Threat

Persicaria wallichii can be found in moist soils and in fields, pastures, and waste areas. It is native to the Himalayan region.

Selected Images

Maps

Invasive Listing Sources

• California Invasive Plant Council
• California Noxious Weeds
• Native Plant Society of Oregon, 2008
• Oregon Noxious Weeds
• Pacific Northwest Exotic Pest Plant Council, 1998
• Washington Noxious Weeds
• WeedUS - Database of Plants Invading Natural Areas in the United States

References