knotweed
(Genus Polygonum)
Origin
There are many species in this genus that are found around the world.
Appearance
Polygonum species is an herbaceous plant that can be annual or perennial. They have swollen nodes (joints) where the leaves attach to the stem.
Foliage
The leaves are attached alternately on the stem. Leaves are long, narrow and willow-like. The leaf base has a membrane (ochrea) which encircles the stem.
Flowers
The small flowers can be pink to white and are held on spikes that can be several inches long. They flower year-round. The flowers of many Polygonum species are bisexual.
Fruit
Fruits have three sides.
Ecological Threat
Polygonum species grow in marshes, swamps, wet forests and ditches.
There are many species in this genus that are found around the world.
Appearance
Polygonum species is an herbaceous plant that can be annual or perennial. They have swollen nodes (joints) where the leaves attach to the stem.
Foliage
The leaves are attached alternately on the stem. Leaves are long, narrow and willow-like. The leaf base has a membrane (ochrea) which encircles the stem.
Flowers
The small flowers can be pink to white and are held on spikes that can be several inches long. They flower year-round. The flowers of many Polygonum species are bisexual.
Fruit
Fruits have three sides.
Ecological Threat
Polygonum species grow in marshes, swamps, wet forests and ditches.
Selected Images
Maps
EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit www.eddmaps.org
State Lists - This map identifies those states that have this species on their invasive species list or law.
Taxonomic Rank
| Domain: Eukarya |
| Kingdom: Plantae |
| Phylum: Magnoliophyta |
| Class: Magnoliopsida |
| Superorder: Caryophyllanae |
| Order: Caryophyllales |
| Family: Polygonaceae |
| Polygonum |
References
Common Name Reference: USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.
Scientific Name Reference: USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.