New York Natural Heritage Program
Seabeach Knotweed
Polygonum glaucum Nutt.
Dicots
Polygonum glaucum Kimberly J. Smith
Family: Buckwheat Family (Polygonaceae)

State Protection: Rare
listed species have: 1) 20 to 35 extant sites, or 2) 3,000 to 5,000 individuals statewide.

Federal Protection: Not Listed

State Rarity Rank: S3
A State Rarity Rank of S3 means: This plant is rare in New York (typically 21-50 populations, limited number of individuals, or limited range).

Global Rarity Rank: G3
A Global Rarity Rank of G3 means: This species is either rare and local throughout its range (21 to 100 occurrences), or found locally (even abundantly at some of its locations) in a restricted range (e.g. a single physiographic region), or is vulnerable to extinction throughout its range because of other factors.


Did you know?
Even though this beach plant seems secure on Long Island, our state has the most populations in the world and the species is much more rare in other parts of its range.

State Ranking Justification [-]
There are 43 existing populations but about half of them are small with less than 100 plants. There are no other older populations which have not been rediscovered. Numbers fluctuate from year to year in its dynamic beach habitat so quantity and quality of populations are based upon five-year averages.

Short-term Trends [-]

Long-term Trends [-]