Potamogeton crispus, the curly-leaf pondweed, is a species of aquatic plant

Aquatic plant

Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...

 native to Eurasia

Eurasia

Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

 but perhaps better known as an introduced species

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

 and often a noxious weed in North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

.
This plant is a rhizomatous

Rhizome

In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...

 perennial herb producing a flattened, branching stem up to a meter long. The leaves are linear or oblong in shape, narrower than broad-leaved pondweed

Potamogeton natans

Potamogeton natans L. is an aquatic species in the genus Potamogeton native to quiet or slow-flowing freshwater habitats throughout the Holarctic Kingdom....

, bog pondweed

Potamogeton polygonifolius

Potamogeton polygonifolius L. or Bog Pondweed, is an aquatic species in the genus Potamogeton. It is found in shallow peaty acid water and bog pools.-Description:...

, fen pondweed

Potamogeton coloratus

Potamogeton coloratus L. or Fen Pondweed, is an aquatic species in the genus Potamogeton. It is found in shallow peaty acid water and fens.-Description:...

, shining pondweed

Potamogeton lucens

Potamogeton lucens or Shining Pondweed, is an aquatic species in the genus Potamogeton. It is found in slow moving fresh water, found locally in the south, mid and East of England, almost rare in the rest of Great Britain.-Description:...

, and perfoliate pondweed

Potamogeton perfoliatus

Potamogeton perfoliatus L. is an aquatic species in the genus Potamogeton occurring in both quiet and flowing freshwater or brackish-water habitats in Central and North America, Eurasia, Africa and Australia.-Description:The leaves are all submerged, oval, translucent, with no stalk, up to 8cm...

. The thick leaves are up to 8 centimeters long and nearly one wide, and they are distinctive for their ruffled or wavy, serrated edges. They lack petioles

Petiole (botany)

In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...

. Turions occur in leaf axils and at stem tips.

The inflorescence

Inflorescence

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

 is a short spike of flowers emerging above the water surface. It flowers from May until October. The turions of the plant develop along with the fruits and germinate

Germination

Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...

, leaving the newly sprouted plants to overwinter.

Environmental Impact

This pondweed is an invasive species now found across most of North America. It was introduced accidentally to the Great Lakes

Great Lakes

The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...

 and inland lakes within that region. The plant thrives in conditions normally less habitable to native plant species. It competes with native plant life and sometimes displaces it. It clogs waterways, inhibiting aquatic recreation and is considered a nuisance in some areas.

External links

• Jepson Manual Treatment
• USDA Plants Profile
• Washington Burke Museum
• Photo gallery
• GLANSIS Species FactSheet
• Species Profile- Curly Pondweed (Potamogeton crispus), National Invasive Species Information Center, United States National Agricultural Library
  United States National Agricultural Library
  The United States National Agricultural Library is one of the world's largest agricultural research libraries, and serves as a National Library of the United States and as the library of the United States Department of Agriculture...
  
  . Lists general information and resources for Curly Pondweed.