New York Natural Heritage Program
Hudson River Water-nymph
Najas muenscheri Clausen
Najas guadalupensis var. muenscheri Troy Weldy
Family: Water-nymph Family (Najadaceae)

State Protection: Endangered
listed species are those with: 1) 5 or fewer extant sites, or 2) fewer than 1,000 individuals, or 3) restricted to fewer than 4 U.S.G.S. 7 minute topographical maps, or 4) species listed as endangered by U.S. Department of Interior.

Federal Protection: Not Listed

State Rarity Rank: S1
A State Rarity Rank of S1 means: This plant is endangered/critically imperiled in New York because of extreme rarity (typically 5 or fewer populations or very few remaining individuals) or is extremely vulnerable to extirpation from New York due to biological factors.

Global Rarity Rank: G5T1
A Global Rarity Rank of G5T1 means: Critically Imperiled globally - The subspecies/variety is at very high risk of extinction due to extreme rarity or other factors; typically 5 or fewer populations or locations in the world, very few individuals, very restricted range, very few remaining acres (or miles of stream), and/or very steep declines. (The species as a whole is common globally.)

Did you know?
Hudson River water-nymph is an endemic taxon in New York. In other words the only place in the whole world where it occurs is New York along the Hudson River. It is one of about three endemic taxa that occur in New York (Weldy and Werier 2005). The subspecific name muenscheri is named after Walter Muenscher (Clausen 1939) a botanist from New York who among other projects studied the aquatic plants along the Hudson River. According to Robert Clausen (1939), who named this taxon, Muenscher has contributed more than any other botanist to the knowledge of aquatic vegetation in New York.

State Ranking Justification [-]
This taxon is a globally rare New York State endemic. It is only known from the southern part of the Hudson River. Historically this species was quite abundant in the Hudson River from Piermont just south of the Tappan Zee Bridge north to the junction with the Mohawk River near Waterford. Over this range there are at least 20 distinct populations which have not been seen in over 70 years. There are 2 populations that are still known to be extant.

Short-term Trends [-]

Long-term Trends [-]