Phragmites along a pond.

7 Invasive and Native Aquatic Plants In Virginia And The Mid-Atlantic

Virginia – and much of the mid-Atlantic – is characterized by a large breadth and depth of habitats, environments, temperatures and more.

For example, Virginia has oceans, marshes, wetlands, stormwater ponds, lakes and ponds. It also ranges from 102 degrees in the dead of summer to -5 in the trenches of winter. And – it has a massive range of vegetation, including northern, southern and a medley of imported aquatic plants.

Today, we’re breaking down some of the aquatic plants you might swim into in Virginia. Interested in learning about aquatic vegetation in general? Check out our guide here.

What is Duckweed?

An image of a duckweed colony.Duckweed or Lemnoideae typically grows in dense groups in still water (water that is not disturbed by tides or boating).

  • Size and Shape: 1/16-1/8 inches long in a flat, oval shape
  • Appearance: large clusters of 1-3 light green leaves floating on a surface
  • Be Careful: While Duckweed is native and provides shelter and nutrients to micro invertebrates, it grows quickly and aggressively. This results in the surfaces of ponds being covered to the point of depleting oxygen – which can kill off fish populations and submerged plants.
  • How to Control Duckweed: Duckweed can be controlled or removed via manual rake pulling, by installing an aerator to disrupt still water, or via certain herbicide applications.

What is Watermeal? 

A close-up image of watermeal.Watermeal or Wolffia is a small, barely visible to the naked eye aquatic plant, often found in large groups near duckweed on the surfaces of lakes, ponds, and marshes.

  • Size and Shape: Flat oval or spherical, reaching 0.2 to 1.5 millimeters
  • Appearance: Watermeal is an extremely small rootless, floating plant that grows in large colonies
  • Invasive yet Native: Watermeal is native to North America but can grow quickly, covering the surfaces of ponds and leading to oxygen depletion. Thus, it can be considered an aggressive, nuisance aquatic plant.
  • How to Control Watermeal: Due to its small size, it’s very difficult to manually remove or rake watermeal. Instead, opt for herbicide applications or even biological management such as fish – but make sure to consult with a local expert, such as Clarke’s Richmond Lake Management office.

What is Spatterdock?

An image of spatterdock with its yellow flower.Spatterdock (also known as Cow Lily or Nuphar lutea) grows in ponds, shallow lakes, and springs, trailing along the waterbody’s floor with no roots.

  • Size and Shape: 1-foot long and 10-inches wide emersed leaves with thin emersed leaves
  • Appearance: Large green leaves which float on or emerge forth from the surface with small round flowers that cave inwards rather than outwards
  • Pros and Cons: Spatterdock acts as a food source for deer, livestock, beavers, muskrats, ducks, and more. And while it is not considered invasive, it does contain an extensive rhizome system that enables it to grow out of control if not managed properly – especially in shallow waterbodies.
  • How to Control Spatterdock: You may be tempted to manually pull out spatterdock, but it’s nearly impossible to remove all of the remaining ribosomes or seeds. Instead, opt for a herbicide treatment with chemicals shown to successful at treating Spatterdock. Contact our Richmond Lake Management office to learn more.

What is Curly Leaf Pondweed?

A dense mat of curly leaf pondweed forming underwater.Curly Leaf Pondweed or Potamogeton crispus can be found in farm ponds, streams, and other still, muddy waters.

  • Size and Shape: Up to 2-meters in length with up to 0.5-inches leaves
  • Appearance: Long, green to reddish stalks with many short, frayed leaves. May contain many branches and grow in dense mats.
  • A Non-Native Plant:  Curly Leaf Pondweed is an invasive aquatic plant species brought over from Europe – it should not be introduced to new waterbodies and immediately treated with herbicide whenever found.
  • How to Control Curly Leaf Pondweed: Similar to Spatterdock,  Curly Leaf Pondweed’s roots and seeds make it difficult to manually remove. You can try using a pond dye to limit the amount of sun penetration, but this can affect other plants and wildlife within the pond. Other options include introducing grass carp or applying specialized herbicides.

What is Northeastern Bulrush? 

A filed with northeastern bulrush growing within it.Northeastern Bulrush or Scirpus ancistrochaetus
grows along the edges of small wetlands, sinkhole ponds or marsh areas with seasonally fluctuating water levels.

  • Size and Shape: Long, triangular-shaped stem with long, thin, flat leaves
  • Appearance: Emergent, long thick, triangular-shaped stems with long, thin leaves. Has chocolate-brown colored seeded fruit surrounded by ‘scales’ that hang off the plant
  • A ‘Relict’ Plant’: Northeastern Bulrush was first identified as a distinct species in 1962 and, while now sparse, is thought to have been once widespread. In this case, relict means that the Northeastern Bulrush is a persistent remnant of an otherwise extinct species. Essentially an aquatic plant dinosaur!
  • How to Control Northeastern Bulrush: This Mid-Atlantic aquatic plant can be removed manually by grasping at its base and pulling or via herbicidal treatments.

 What is Alligatorweed? 

Alligatorweed, also known as Alternanthera philoxeroides, is native to South America and invasive in North America and can be found both on dry land and water – although it prefers most to grow along the shores of streams and ponds.

  • Size and Shape: Stems reach 1-meter in length with extending narrow, elliptical leaves
  • Appearance: Stems are pink and hollow with its leaves extending outward from it. White flowers with thin petals grow on stems extending 4-5-inches from the main stem.
  • A Nuisance: Alligatorweed grows in mats, disrupting waterflow, outcompeting native vegetation and depleting oxygen levels leading to fish kills. These mats can also impact recreational activities such as boating and fishing, making for an overall unwanted aquatic plant.
  • How to Control Alligatorweed: Herbicides will usually do the trick when it comes to Alligatorweed, and should be treated while it’s still in its early stages of growth. More mature Alligatorweed plants have a tendency to be herbicide-resistant or are protected by growing in dense mats.

What are Phragmites? 

A large example of a phragmite.Phragmites (or the Common Reed) is a tall wetland invasive species thought to come from either Europe or China.

  • Size and Shape: Long, grass-like stems reaching 15 ft
  • Appearance: Appear as long grass (up to 15 ft) with dark, elongated leaves and topped by bushy, purple or gold panicles
  • Two Sides of a Coin: While much news surrounding phragmites is concerning its invasive strains, native strains have been recorded in the United States as far back as 40,000 years ago. It was also found to have been used by Native Americans for arrows, musical instruments, ceremonial objects, mats and more.
  • How to Control Phragmites: Manual methods usually aren’t recommended for the common reed as they leave roots intact (and can make the problem even worse). Instead, consult a Virginia-based pond specialist about aquatic herbicides or even burning roots.

Looking for Management of Your Warerbody’s Aquatic Plants? 

Our experts at Clarke have years of experience working with a vast variety of lakes, ponds, stormwater ponds and more throughout the United States, with a focus on catering to their unique needs and goals and an emphasis on using science-based techniques and technologies to do so. For a free assessment or any questions regarding your waterbody’s quality, contact our team here.

Learn more about aquatic plants, what makes them invasive versus native and more with Clarke’s Guide to Native and Invasive Plants and Weeds.