Curly-leaf pondweed
(Potamogeton crispus)
Biological Category
Plants
NY Legal Status
Prohibited
Species Type
Aquatic Invasives
DESCRIPTION
Potamogeton crispus grows entirely as a submersed aquatic plant with no floating leaves. Leaves are conspicuously toothed along leaf margins, attached directly to the stem, narrowly oblong, undulate with a conspicuous mid-vein. Leaf tips are obtuse olive-green to reddish-brown, and somewhat translucent. Stems are flattened, channeled, with few branches. Rhizomes are pale yellow or reddish, rooting at the nodes. Small flowers with greenish-brown or greenish-red sepals form on a terminal spike above the waterline producing 3-4 achenes per flower.
Note: Research for these pages was generated from citations listed. References for specific statements available upon request.
Leaves: A mid-rib is present.The leaves are characteristically linear-oblong, 1-3 inches long, around .5 inches wide and are arranged spirally along the stem.
Flower: This plant flowers and fruits in late spring to early summer, but then dies leaving fruit and turions to generate new plants in the late summer and early fall.
Stem: The plant has flat stems, and spindle-shaped 1-inch buds that are found terminal or axillary.
Size: Curly-leaved pondweed is an aquatic perennial that reaches between 1 and 2.5 ft. in length.
The first verified report of P. crispus in North America came from Philadelphia, PA in 1841-42, and after initial introduction, the plant began to establish quickly. By 1860, its growth in Delaware and Pennsylvania was described as abundant, and it spread rapidly in areas of Massachusetts and New York by the early 1880s. Occurrences were subsequently reported just west of the Mississippi River by 1903, and by 1896, the population had spread to the western seaboard
It is hypothesized that accidental introduction during stocking activities was the primary vector for spread in New England, and also noted that the plant was at first intentionally planted due to its suitability as habitat and food source for wildlife.
Potamogeton crispus grows entirely as a submersed aquatic plant with no floating leaves. Leaves are alternate, 4-10 cm in length and 5-10 mm wide. Leaves are conspicuously toothed along leaf margins, attached directly to the stem, narrowly oblong, undulate with a conspicuous mid-vein. Leaf tips are rounded or blunt, olivegreen to reddish-brown, and somewhat translucent. Stems are flattened, channeled, with few branches. Rhizomes are pale yellow or reddish, rooting at the nodes. Small flowers, with greenish-brown or greenish-red sepals form on a terminal spike above the waterline producing 3-4 fruits per flower.
Curly-leaved pondweed grows in a variety of water conditions, and can be seen growing in lakes, ponds, rivers, streams and salt marshes. It is fairly tolerant of brackish water as well as fresh water. Although it thrives best in nutrient-dense and alkaline waters, it competes with native plants under other water conditions as well. These plants tend to form dense mats to the surface of the water, frequently inhibiting growth of native plants. Along with impacting native plant growth, these mats can be detrimental to recreation, by interfering with boats and other water sports. Because their germination occurs in the fall, they overwinter under ice and become one of the first plants to grow in the spring, giving them distinct advantage and more resources. During the summer, when the plants die off, the excess decaying organic matter makes the water extremely eutrophic, also potentially causing detrimental algal blooms
Invasive species cause recreational, economic and ecological damage—changing how residents and visitors use and enjoy waters.
Curly-leaf pondweed impacts: Forms dense mats at the water’s surface that inhibits water recreationists. Overtakes habitat and outcompetes native aquatic plants, potentially lowering diversity. Provides unsuitable shelter, food, and nesting habitat for native animals. Midsummer die-offs can litter the shoreline with dead plants.
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