New York Natural Heritage Program
Douglas' Knotweed
Polygonum douglasii Greene
Dicots
Polygonum douglasii Stephen M. Young
Family: Buckwheat Family (Polygonaceae)

State Protection: Threatened
listed species are those with: 1) 6 to fewer than 20 extant sites, or 2) 1,000 to fewer than 3,000 individuals, or 3) restricted to not less than 4 or more than 7 U.S.G.S. 7 minute topographical maps, or 4) listed as threatened by U.S. Department of Interior.

Federal Protection: Not Listed

State Rarity Rank: S1S2
A State Rarity Rank of S1S2 means: Critically Imperiled or Imperiled in New York - Especially or very vulnerable to disappearing from New York due to rarity or other factors; typically 20 or fewer populations or locations in New York, very few individuals, very restricted range, few remaining acres (or miles of stream), and/or steep declines. More information is needed to assign a single conservation status.

Global Rarity Rank: G5
A Global Rarity Rank of G5 means: This species is demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery.


Did you know?
The genus name "Polygonum" is derived from the Greek for "poly", meaning many, and "gonu", meaning knee -- a reference to the many swollen joints, or nodes, along the stems of the plants (FNA 2005). Douglas' Knotweed is named for David Douglas, a Scottish plant collector of the early 19th century, who explored the northeast, Canada, California, and Hawaii for the Horticultural Society of London (Charters 2008).

State Ranking Justification [-]
There are only 5 verified occurrences in the state, 3 of which are ranked "good" with more than 100 individuals. There are 17 historical records, most of which have never been checked.

Short-term Trends [-]

Long-term Trends [-]