Curlyleaf Pondweed
Category
Invasive Macrophyte
Common Name
Curlyleaf Pondweed
Species Name
Potamogeton crispus
Distribution / Status (Lake Tahoe)
Established invasive in Tahoe Keys and several nearshore sites along south shore, common in and near marinas
Diagnostic Features
Crinkled, serrated leaves like lasagna noodles; presence of turions at stem tips
Commonly Confused Species
Richardson's Pondweed (Potamogeton richardsonii)
Growth Form
Submersed perennial macrophyte
Leaf Shape
Narrowly oblong; distinctly crinkled or wavy (curled edges)
Leaf Arrangement
Alternate along stem
Leaf Size
4–10 cm long × 0.5–1.5 cm wide
Leaf Margin
Strongly serrated and crisped (ribbon-like curls); very wavy (key ID trait)
Leaf Apex & Base
Apex blunt; base clasping the stem with small auricles
Venation Pattern
Five to seven strong parallel veins easily visible
Stem Structure
Flattened, brittle, often reddish-brown near base
Plant Height
Up to 5 m
Roots / Rhizomes
Fibrous roots; yellow or reddish at nodes; also produces specialized overwintering buds (turions)
Habitat Type
Eutrophic to mesotrophic waters, often in disturbed or nutrient-rich areas; can grow in low temperatures (1–4 °C)
Depth Range
0.4 - 10.5 m
Substrate Preference
Soft, silty sediment preferred
Light Preference
Tolerates low light; can colonize shaded areas
Ecological Role / Impact
Outcompetes native macrophytes; forms dense mats early in season, shading out others; impedes water flow, and disrupts navigation
Flowers (Reproductive Structures)
Small flowers on emergent spikes; also produces turions at stem tips for overwintering; early June (10–15 °C)
Reproductive Strategy
Primarily vegetative via turions; regrows early in spring before natives
Buoyancy / Adaptations
Turions sink and germinate early; leaves contain air spaces aiding buoyancy
Color
Olive to reddish-brown, slightly translucent
Texture
Brittle, coarse, and “crispy” to the touch
Growth Rate / Seasonality
Very rapid growth rate (8–10 cm/day); peaks early in spring; senesces by midsummer (July)
References
Holm, L., Doll, J., Holm, E., Pancho, J., & Herberger, J. (1997). World weeds: natural histories and distributions. John Wiley and Sons, Inc., New York, NY.
Knoke, D., & Giblin, D. (n.d.). Potamogeton crispus: curly pondweed. Burke Herbarium Image Collection, University of Washington.
Tobiessen, P., & Snow, P. D. (1984). Temperature and light effects on the growth of Potamogeton crispus in Collins Lake, New York State. Canadian Journal of Botany, 62, 2822–2826.
U.S. Geological Survey. (n.d.). Potamogeton crispus (curly-leaf pondweed). Retrieved from https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=1134
Supporting Partners
The Martis Fund, a collaborative project of Martis Camp landowners, DMB/Highlands Group (the developers of Martis Camp), Mountain Area Preservation (MAP), and Sierra Watch. (See martisfund.org for more information)
The Community Impact Fund, Ashley Quinn Fund & the Foresight Fund held at the Tahoe Community Foundation
Additional thanks to the Tahoe Regional Planning Agency for providing specimens for studio filming
