New York Natural Heritage Program
Riverweed
Podostemum ceratophyllum Michx.
Dicots
Podostemum ceratophyllum plants Stephen M. Young
Family: (Podostemaceae)

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: S2
A State Rarity Rank of S2 means: This plant is threatened/imperiled in New York because of rarity (typically 6-20 populations or few remaining individuals) or is vulnerable to extirpation from New York due to biological factors.

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?
This is the only member of this genus and family that occurs in North America. The genus is confined to the New World (Philbrick and Novelo 2004). The genus name Podostemum comes from the greek words for foot and stamen and is in reference to the stamens appearing "raised on a stalk by the side of the ovary" (Fernald 1970). The specific epithet ceratophyllum means horn-leaf (Fernald 1970) and may be in reference to the narrow stiff leaves of this species.

State Ranking Justification [-]
There are 16 known extant populations and 8 populations which have not been seen in recent years and are considered historical. Many of the populations are clustered along particular rivers. Habitat is somewhat limited for this species but certainly not rare.

Short-term Trends [-]

Long-term Trends [-]