SafePlants

Podostemum ceratophyllum: Hornleaf Riverweed

Podostemum ceratophyllum, commonly known as hornleaf riverweed, is an aquatic plant found in flowing-water environments. This perennial herb belongs to the Podostemaceae family, also known as the Riverweed Family.

Taxonomy and Nomenclature

• Scientific Name: Podostemum ceratophyllum Michx.
• Family: Podostemaceae (Riverweed Family)
• Genus: Podostemum Michx.
• Species: Podostemum ceratophyllum Michx.
• Synonyms: Podostemum abrotanoides Nutt. (=)
• Other Common Names: threadfoot, podostmon feuilles cornes

Distribution and Habitat

Hornleaf riverweed thrives in shallow, fast-running water, often rooted on submerged boulders and rock outcrops. It has been observed in locations like the Red River in Wolfe County, Kentucky, and is found in various states including ME, NH, VT, MA, CT, and RI. It appears to be more widespread than previously thought, according to the New York Metropolitan Flora Project.

Morphological Characteristics and Growth Habits

Podostemum ceratophyllum is a perennial forb/herb, meaning it is a non-woody plant that lives for more than two years. The specific epithet "ceratophyllum" means horn-leaf, referring to the narrow, stiff leaves characteristic of this species.

Ecological Role

This aquatic macrophyte provides essential habitat for invertebrates and fishes in flowing-water ecosystems. It is sometimes associated with larger cobbles and boulders along with aquatic mosses in shoals.

Note that there are some references to it being threatened in certain areas.

Three species of potential concern are associated with Hornleaf Riverweed (Podostemum ceratophyllum Michaux, 1803).

Interactions with Other Organisms

Hornleaf riverweed serves as a specific larval habitat for some of the rarest mayflies.

Further Information

For more information, consult the following resources:

• USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States.
• Discover Life
• The Integrated Database