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​Submerged Aquatic Plants

There are several submerged aquatic plant species. Some may be more prevalent in certain areas of Virginia than others. Submerged aquatic vegetation are plants that are completely under the water and typically have a root system in the bottom sediment. They require the water for physical support of the plant structure.

The difference between desirable submerged aquatic plants and undesirable varieties is personal taste (how the plants look) and balance. A beautiful plant that takes over the entire pond can quickly turn from one that is pleasant to one that needs to be removed. Keeping plant species in check and in balance will create a beautiful pond setting. Below are some common submerged aquatic plants found in Virginia and some information about them.

Eelgrass (Zostera marina) is a native perennial that has ribbon like leaves that rise from the base of the plant up to 7 feet long.  The leaf tips are pointed and have very few teeth on the margins.  Midrib is absent.  The plant produces tiny white flowers in the spring at the base of the plant that will break free and float freely on the water’s surface.  This aquatic plant is attractive to wildlife and is seldom a problem except in shallow waters during the summer when it tends to grow rapidly.

Brazilian Waterweed/Elodea (Egeria densa) is an exotic perennial introduced from South America.  Prior to the arrival of hydrilla, Brazilian Elodea was the most troublesome aquatic plant in Virginia.  Often confused with hydrilla and Canadian elodea.  Hydrilla leaves are prominently toothed, whereas the teeth of the Brazilian elodea are barely visible with your eyes.  Canadian Elodea prefers moving water.  Brazilian elodea prefers still water and is generally larger than Canadian elodea.  Its stems will grow longer than 6 feet.  The leaves grow in whorls of 3 to 6 and are narrow, 1” to 1 ¼” long and 1/10” to 1/5” wide.  A single white flower with 3 petals grows at the end of the stem, protrudes above the water, and grows throughout the season.  This aquatic plant will grow rapidly in the spring and summer forming large dense mats that will choke out other plants and restrict recreation activities.

Brittle or Slender Naiad (Najas Minor) is an exotic annual introduced from Europe.  Its stems will reach 4 feet or more and the leaves are 1 ½” long, pointed, have distinct teeth along the margins, and are only found at the end of the stem.  Southern naiad leaves are evenly dispersed along the stem.  The flowers are tiny and inconspicuous like the southern naiad and grow at the base of the leaves.  Naiads are valuable to wildlife and fish.  They only become a problem when they create an impenetrable mass on the surface of the pond or lake.

Canadian Elodea or Common Waterweed (Elodea canadensis) is commonly confused for hydrilla or Egeria (Brazilian Elodea), but is much smaller in size.  Stems reach 7 to 9 feet long. The leaves are bright green, in whorls of 3 toward the end of the stem, and elliptic to oblong. The non-showy small white flowers (1/6” – 1/3” wide) of this native perennial are produced from mid-summer to fall. Rarely a nuisance, but should be kept in check to limit spreading.  Often found near stream inlets or flowing water, it provides cover for fish and harbors the insects that fish eat. 

Coontail (Ceratophyllum demersum) is a native annual submersed aquatic plant.  This rootless aquatic plant will float freely or its stem will attach to a substrate with a rhizoid (a root like structure).  The feathery, fan shaped leaves are arranged in whorls with small teeth and resembles a raccoon’s tail.  Often confused with watermilfoil, look for coontail’s singly forked, spiny leaves.  Late summer to early fall, coontail will produce tiny non-showy flowers at the base of their leaves.  Coontail can grow very tall (15') and occur in deep clear water areas. Seldom a nuisance, but controlling the spread of coontail can be difficult since it is free floating.  In fact, coontail provides food for fish and waterfowl and it also harors small aquatic animals. 

Curly-leaf Pondweed (Potamogeton crispus) is the only exotic pondweed species in Virginia.  It gets its name from its wavy leaf margins.  The leaves are flat with a round tip and grow up to 2” to 3” long.  Its margins have sharp teeth and an obvious midrib that is often reddish in color.  The plant itself will grow up to 6’ tall and can be found in shallow water or depths up to 12’.  The flowers are seen in the spring and dieback typically happens in early July.

Fanwort (Cabomba caroliniana) is a native annual plant in Virginia that is often confused with Chara.  Further south this plant will grow as a perennial.  Its distinctive soft flexible fanlike shaped leaves are divided into many segments.  Sometimes distinctive floating elliptical leaves (1/2” – ¾” in diameter.) will grow at the tops of the stems.  Their flowers have six white, pink, or purplish petals with spots at the base.  The flower is seen throughout the summer months above the water surface and is 1/3” to ½” wide.  It primarily occurs in eastern Virginia and seldom causes problems.  

Hydrilla (Hydrilla verticillata) is an undesirable exotic perennial from Africa and Australia.  This plant can adapt to a wide range of water temperatures and pH levels.  These factors allow it to out compete native plants in your lake or pond.  Hydrilla is often mistaken for Canadian elodea and Brazilian elodea.  The leaves grow in whorls of three to eight on the upper portion of the plant.  They are oblong to oval shaped with toothed margins and spines on the lower side of the leaf on the midrib.  The toothed margins and spines on the lower midrib are what give the Hydrilla a rough texture.  Their tiny translucent flowers (1/4” wide) grow at the end of a stalk and appear in the summer and fall.  Because of their reproductive nature and ability to grow quickly, Hydrilla is very difficult to control once it has established in a lake or pond.

Leafy Pondweed (Potamogeton foliosus) is a native perennial that grows in slow moving streams and lakes in water up to 8 feet deep.  It will reach lengths up to 6 feet with both submersed and floating leaves.  The floating leaves are 3”-5” long, 1”-1/2” wide, shiny, oval shaped, have a distinct midrib, and about a 6 inch leaf stalk attached to the plant stem.  The submersed leaves are about 8 inches long by a ½” wide.  Its flowers are 1” to 2 ½” spike, cream to pink in color and will appear above the water surface from May through October.  They provide excellent habitat and food for fish, waterfowl, and other aquatic organisms.

Parrot Feather (Myriophyllum aquaticum) is an exotic perennial that escaped from South America.  It grows primarily in 3 feet or less of water during the fall, winter, and early spring.  Parrot feather is often confused with Chara.  Parrot feather has pale green-gray feathery leaves and Chara is dark green and does not have numerous tiny leaflets growing from each leaf.  The parrot feathers stem is orange and reddish in color and often extend above the water surface.  Chara will appear as a large dense mat in the water, whereas individual plants are more obvious in parrot feather mats.  Its flowers are tiny, white, and inconspicuous and are found at the base of the emersed leaves.  The large surface mats of parrot feather hinder recreation activities.

Pondweed (Potamogeton spp.) There are 4 species of pondweeds in Virginia.  This diverse group of aquatic plants can be difficult to identify.  Water depth, water current/speed, water clarity, water temperature, climate, and nutrients influence the growth and appearance of the pondweeds in Virginia.  Where the plant is growing and the size and shape of its leaves are the best way to distinguish between the species.

See leafy pondweed, small/slender pondweed, variable-leaf pondweed, and curly-leaf pondweed.

Small/Slender Pondweed (Potamogeton pusillus) is a native perennial found throughout Virginia that grows in slow moving streams and lakes in water up to 8 feet deep.  Look for several branches on a slender stem.  Submersed branches do not have leaves.  The narrow ribbon like leaves are 1” to 2” long and will be floating on the surface.  A whitish pink flower spike will be found above the water surface. They provide excellent habitat and food for fish, waterfowl, and other aquatic organisms. 

Southern Naiad (Najas guadalupensis) is a native annual in Virginia.  Its stems will reach several feet in length and the leaves are about 1” long (Narrow, but wider at the base.), the teeth along the margins can only be seen with the aid of a magnifying glass, and are evenly dispersed along the stem.  Brittle/Slender naiad leaves are only found at the end of the stem.  The flowers are tiny and inconspicuous like the brittle/slender naiad and grow at the base of the leaves.  Naiads are valuable to wildlife and fish.  They only become a problem when they create an impenetrable mass on the surface of the pond or lake. 

Variable-leaf Pondweed (Potamogeton diversifolius) is a native perennial that prefers shallow water.  It has floating leaves that are oval, up to 2” in diameter and attached to a stem.  Its submersed leaves are thin and linear. ½” to 2 “ long and attached directly to the stem.  The flower is a small whitish to pink flower spike found above the water surface from Spring to Fall.  They provide excellent habitat and food for fish, waterfowl, and other aquatic organisms.

Watermilfoil (Myriophyllum spicatum) is not native to the US and is an extremely invasive species. There are strict regulations for boats in lakes that contain eurasian watermilfoil because small pieces that break off can stick to boats and trailers and then re-root in other bodies of water. The leaves are feather-like and are limp when out of water. The leaves are arranged in circles of 3 to 5 around a long, spaghetti stem. The plants can grow over 10' tall. The tops of the stems often are reddish in color.

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Floating Aquatic Plants

As the name implies, these are plants that are free floating at the surface or have leaves that float. They typically have some sort of root system that hangs below the plant and filters the water for nutrients. Two common undesirable or nuisance floating aquatic plants (not including algae which is discussed individually on the Algae page) are Duckweed and Watermeal. These two species of aquatic plants can cover a pond and create a very unappealing pond or lake. They also block out sunlight from reaching the rest of the water column which limits growth of other aquatic plants and can limit the amount of oxygen available for your fish. Some more desirable native floating aquatic plants, in moderation, are American Lotus, Water Lily (Lily Pads), and Watersheild. These plants are considered more desirable because they enhance the aesthetics of a pond and create nice flowers. However, they can overrun a pond and become undesirable if not controlled.

American Lotus (Nelumbo lutea) is sometimes mistaken for Waterlily.  The leaves are green on both sides and will reach 2 feet in diameter.  The stem attaches to the center of the leaf and unlike the waterlily, these leaves do not have a cleft or a split.  The bright yellow flower is 4 – 6 inches wide.  When the petals fall off the seedpod is exposed.  This seedpod resembles a shower head pointing up and is sometimes sold in flower arrangements.  This native perennial is not normally a nuisance.  If removal is needed, manual removal is temporary, an application with an aquatic herbicide will provide long term results. 

Azolla (Azolla caroliniana) is an exotic aquatic fern found in swamps, lakes, ponds, and ditches in southeastern Virginia.  It is often confused with duckweed or Watermeal.  In groups duckweed and Watermeal will appear shiny green, where azolla will be velvety green to reddish green to purple depending on the health of the plant.  Green indicates a healthy plant.  Reddish green to purple indicates the plant is under stress.  Each leaf has 2 lobes.  One will be found submerged and the other floating.  The stems will be branched and covered with leaves.  Even though the plant floats, their roots will appear below the plant.  The individual plant is smaller than a dime, but appears as a large mass because they grow in groups.  Because of their rapid growth they will often outcompete native species of submersed plants and will interfere with recreational activities in the summer months. 

Bladderwort (Utricularia purpurea) can be a submersed or emersed floating plant.  It is a native perennial that can live in ponds, lakes, and ditches in southeastern Virginia with limited nutrients available. It is actually a carnivorous plant. It can look like an unorganized mess in your pond, but it eventually comes together to form the "starfish" shape and then shoots up white, purple, or yellow flowers.  Yellow is more common and appear throughout the season. They have numerous small black bladders on their leaves and stems that hang below that open and catch small organisms like zooplankton. Bladderwort can be a pain if it takes over your pond and since it isn't as dependent on nutrients in the pond, it can spread rapidly.

Duckweed (Lemna spp. Or Spirodela spp.) is a small, green, round or oval aquatic perennial that floats at the surface with a root that hangs below. Duckweed is transferred or spread by humans and wildlife (ducks, geese, turtles, etc.). It can quickly spread and cover an entire pond, blocking sunlight for other plants and causing an unappealing pond. Common treatments are with an aquatic herbicide.  Triploid Grass Carp will also eat duckweed.

Water Hyacinth (Eichhornia crassipes) is an invasive plant species that originated from Brazil. It can quickly spread and take over an entire pond; therefore, it is often classified as undesirable. It is characterized by the prominent purple flower. The upper petal of the flower has a yellow spot surrounded by purple. If this species is in your pond, it is important to keep it from spreading too rapidly with treatment or pulling the plants out.

Waterlily (Nymphaea odorata) is a great example of beauty in moderation. Lily pads can greatly enhance the beauty of a pond or water garden with the green pads and the flowers, but they can also quickly overtake a pond if not monitored. They can be held in check by simply pulling the pads out. They have rounded leaves about 6-12" with a cleft or cut to the center. The underside is a purplish red color. A white, fragrant flower is also produced.

Watermeal (Wolfnia spp.) is smaller than duckweed and looks like small green seeds with no roots that hang below. Watermeal will feel gritty between your hands and fingers. Watermeal can be spread by humans and wildlife into new areas. It can also spread quickly and cover an entire pond blocking sunlight and causing an unappealing pond. Common treatments are with an aquatic herbicide. However, watermeal can be more difficult to treat than duckweed.

Watersheild (Brasenia schreberi) has floating lobed leaves similar to the Waterlily, but without the cleft and the leaves are much smaller, typically only about 4" long and 3" wide. The stem and undersides of the leaves are purple and are covered with a thick, gelatinous coating. This can be a desired species depending on personal taste and if it has not overrun the pond.

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Emergent Aquatic Vegetation

Emergent aquatic plants grow in shallow areas, usually along the banks of ponds or lakes, or in shallow marshy areas. Some may not be considered aquatic vegetation, but can survive in wet soils for an extended period of time. Emergent plants, unlike submerged vegetation, are rigid and can stand on their own, without support from the water.

These again, can be desirable or undesirable depending on balance and what you like to see. Often times, emergent vegetation can be very beneficial as a nutrient buffer. They can block or at least slow down nutrients that are entering the pond due to runoff. Emergent vegetation also serves to stabilize the shoreline and reduce erosion. Deep rooted vegetation keeps the shoreline intact. Desirable varieties also provide wildlife food and habitat. Below are some common submerged aquatic plants and some information about them. This section of the page is an ongoing process, so check back for more additions.

Alligatorweed (Alternanthera philoxeroides) is an exotic emersed perennial that was introduced into Virginia from South America.  It will grow anywhere that moist and wet conditions remain constant year round.  It has a hollow stem that will sometimes fill with air, bulging out to a ½” and will appear green, pink, and purplish.  Their flowers are scaly, round, whitish, and their stem grows out from the upper base of its leaves.  The leaves are ½” wide and up to 4” long.  This plant can form large dense mats and block out native vegetation if not controlled.   

Bulrush (Scirpus spp.) is a native aquatic plant that is found mostly in marshy shorelines, in water up to 6’ deep.  There are many species of bulrush, both annuals and perennials, that grow in clumps from 2” to 6’ tall.  Most species have stems that are in the shape of a triangle, but some will be round.  The plant appears leafless, but has long slender green leaves growing as blades or sheathes around the stem.  Loose clusters of brownish flowers and seeds will grow near the tip of the stem in mid-summer through mid-fall.  The stems of this plant will survive the winter and provide valuable spawning areas and cover for fish in the spring.  Ducks, geese, and swans will often eat this plant and is a great attractant for songbirds.

Cattails (Typha spp.) are probably the most recognizable emersed aquatic plant in and around water.  This native plant can be found in marshes, low wetlands, shorelines, and quiet water up to 4’ deep.  The tall stalks or stems with long, green leaves are very recognizable and the 8-10" brown cylindrical spike produces seeds for reproduction. Cattails can spread quickly if not controlled. Cattails serve as cover for wildlife and also as a food source for aquatic rodents, such as Muskrats.

Phragmites (Phragmites australis) is an exotic perennial that is found in the coastal areas of Virginia.  It prefers brackish water and salt marshes, but can also be found along streams and rivers.  Their stems are thin and can reach heights of 10’ or more.  The leaves are a bluish green, ½” wide and up to 1 ½’ long.  A large (Up to 1’ long.) yellowish brown to purplish flower head will form mid-summer to fall.  Once established this aquatic plant is nearly impossible to control and will often crowd out native plants.

Purple Loosestrife (Lythrum salicaria) is an exotic perennial that can be found in marshes, wetlands, lake shoreas and the banks of rivers.  It has a stiff four sided stem and the plant will reach heights of 2’ to 7’ tall.  Its lanced shape leaves with a heart shaped base are arranged opposite of each other in whorls of 3 on the stem.  The most identifiable feature of this plant is its large purplish red flower spike that will appear from July to September.  This extremely invasive plant will produce up to 3,000 seeds per plant per year.  Sightings of this aggressive plant must be reported to the county Extension agent.

Smartweed (Polygonum spp.) There are both native and exotic species of smartweed in Virginia.  These perennials will grow in moist or wet soil along the edges of streams, rivers, lakes, and other aquatic sites.  Their thick fleshy stems (1/2” thick) range in color from green to reddish brown and will grow from 2’ to 8’ tall.  Their leaves mat be large and oval or narrow and small.  The leaves attach to the stem by a leaf petiole or leaf stalk.  The leaf petiole wraps the stem.  This is called an “ocrea”.  The size, shape and color of the ocrea is how you would identify or tell the difference between different species of smartweed.  Their long flower clusters may be 1” to several inches in length and are usually whitish pink in color.  Like most aquatic plants, smartweed will cause problems if not controlled.   

Water Primrose (Ludwigia spp.) There are both native and exotic species of primroses in Virginia.  Some species are annuals and others are perennials.  It produces stems that grow horizontally with roots that are wiry. Their lance shaped or round leaves may alternate or be opposite along the stems. Erect stems occur during the flowering stage and most typically bloom from April to September, depending on species and location.  Their flower is the best way to identify between the species.  Each flower may have 4-6 bright yellow petals arranged in a circle.  Each flower is ½” to 4” in diameter and will be found at the end of a flower stalk.  One plant may produce several flowers along the plant stem. Water primroses are typically considered desirable aquatic plants, but will interfere with recreational activities if not controlled.

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Blue Ridge Wildlife & Pest Management, LLC provides algae identification in Virginia.

Algae are naturally-occurring microscopic organisms that are found in the fresh and salt waters of Virginia.  Most algae species are beneficial because they are major producers of oxygen and food for birds, fish, and other aquatic organisms that live in or around these waters.  

Algae are simple plants that lack true supporting tissue or conducting tissues (vascular tissue).  They do not produce true roots, leaves, or flowers and are often found floating or attached to underwater surfaces in lakes, ponds, and streams.  These plants will start to multiply as the weather starts getting warmer and will turn your lake or pond a deep greenish color.

Planktonic algae (Microcystis spp.) is a free-floating native algae found in farm ponds, reservoirs, and along lakeshores.  They exist as single-cells, small colonies, or filaments that are attached to each other.  Abundant growth turns into planktonic blooms in the summer months that can be bright green, pea soup looking or even a blood red color.  These blooms indicate that the lake or pond is polluted with excess nutrients and can die quickly and deplete the dissolved oxygen supply to the fish in your pond.   They are the base of the food chain and a healthy existing pond or well prepped new pond must have planktonic algae as a food source for aquatic organisms. 

Filamentous algae (Spirogyra spp.) are called many things such as pond scum or moss, and they are typically found at the surface in the form of greenish mats. Typical growth begins on the edges of ponds and will slowly rise until it arrives at the surface. This series of cells joined together has a slimy, cottony or course texture. It can look like the stringy mass or it can be "scum" or a green mat on the water surface. Filamentous algae will grow in ponds with excess nutrients, nitrogen and phosphorus. It is common to have this type of algae encouraged after ponds are limed to enhance fish production. Filamentous algae typically are of little or no value to you or your pond.

Macrophytic (Chara and Nitella) A misconception is that they look like vascular plants, which causes a lot of confusion because they attach to the bottom like a rooted plant. There are two species of marophytic algae that are native in Virginia.  Muskgrass (Chara) and stonewort (Nitella).  Both grow submerged usually in clear water.  Chara has a musky garlic like odor when crushed and has a gritty texture to it.  Nitella is smooth and delicate without any odor when crushed.

Muskgrass (Chara spp.) & Stonewort (Nitella spp.)  are actually native forms of erect algae that can grow a few inches to several feet. They are a great plant for ponds with excessive nutrients because they use up a large amount of nutrients and provide food and hiding for fish and other organisms.  Dense growths may cover the entire bottom of a pond or lake.  They look like several other aquatic plants, but a way to tell it apart is to break the thin straw-like stem. Since it is a single celled stem, if you break it, the entire stem will turn flaccid or limp. Other plants will just break or bend, not turn flaccid. Chara has a strong garlic smell to it and a gritty texture.  Nitella has a smooth and delicate tissues. As with many plants, they are good in moderation.

Algae Blooms

Most algae species will do not harm people, wildlife, or the environment.  But some types of algae in Virginia can be dangerous. Algae species in fresh and salt water may multiply rapidly when environmental conditions are favorable for their development. The great number of algal cells in the water results in what is called an algal bloom. 

A algae bloom often (but not always) results in a color change in the water. Algal blooms can be any color, but the most common ones are red or brown and are known as either “red” or “brown” tides.  Most algal blooms are not harmful but some do affect fish and humans, as well as other animals like birds and marine mammals. These are known as Harmful Algal Blooms (HABs).

Algae Bloom Source: https://www.vdh.virginia.gov/epidemiology/DEE/HABS/

CLICK HERE for more information about Harmful Algal Blooms from the Virginia Department of Health.

If you need pond or lake algae identification in Alexandria, Arlington, Bedford, Blacksburg, Bristol, Charlottesville, Covington, Chesapeake, Danville, Fairfax, Fredericksburg, Hampton, Harrisonburg, Lexington, Lynchburg, Loudon, Manassas, Martinsville, Newport News, Norfolk, Richmond, Roanoke, Smith Mountain Lake, Staunton, Virginia Beach, Waynesboro, Williamsburg, Winchester, Wytheville, and Yorktown Virginia, Blue Ridge Wildlife & Pest Management, LLC is available to properly identify the species of algae in your lake or pond.

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