| Tufted Knotweed | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Core eudicots |
| Order: | Caryophyllales |
| Family: | Polygonaceae |
| Genus: | Polygonum |
| Species: | P. caespitosum |
| Binomial name | |
| Polygonum caespitosum |
|
Polygonum caespitosum or Tufted Knotweed is a summer annual weed plant of the family Polygonaceae, native to eastern and central North America. The plant grows to 3.5 feet in height with elliptic to lanceolate leaves, usually 20-75 mm long. It has small pink or red flowers arranged in tight terminal spikes.
Tufted Knotweed is similar to other polygonum species, particularly Polygonum persicaria (Lady's thumb). Around the stem of both these species there is a papery sheath known as a ocrea with stiff spine-like hairs at the top, but in P. caespitosum these hairs are much longer, as long as the visible portion of the ocrea, whereas in P. persicaria they are much shorter.