Southern naiad is a submerged annual plant that has the ability to form dense colonies and is native to the northeast. The leaves are usually in pairs but the size and spacing of the leaves on this plant are extremely variable. The leaves have a broad base but are narrow and serrated. The flowers for this plant are incredibly tiny and can be found at the base of their leaves. Like Eurasian watermilfoil, this plant can also grow by fragmentation.
There are other similar species of naiads and they are known for their importance as feed to waterfowl. Naiads also serve as an indicator plant as they are known to grow at nuisance levels in disturbed conditions. As is the case with most aquatic plants, southern naiad provides shelter for young fish and invertebrates. This plant can be controlled through the use of biological, chemical, and physical control methods.
Brittle naiad is closely related to southern naiad but this plant has the ability to deal with brackish (moderately salty) water. It can look very similar to southern naiad except its leaves are highly toothed. The leaves can grow to be over an inch and flowers can also be found at the base of their leaves during the summer.
Brittle naiad will grow through fragmentation and easily breaks apart as it name implies. This plant can tolerate poor water clarity and under the right conditions can replace native vegetation. This plant can be controlled through the use of biological, chemical, and physical control methods.
Chara is a genus of macroalgae that has properties of larger vascular plants. Although appearing to be and having properties of a higher plant, it is in fact algae. It is also known as musk-grass due to its musky or skunky smell; the smell is unmistakable. Chara feels crusty because it is covered in calcium carbonate.
This alga can reproduce vegetatively as well as sexually. When reproducing sexually it has distinguishable orange bumps. It prefers muddy or sandy substrate and is more common in waters high in mineral content (hard water). Chara can overwinter and will grow when the weather begins to warm up in early spring. This plant can be controlled through the use of biological, chemical, and physical control methods.
Nitella is another genus of macroalgae and are commonly known as stonewort’s. Similar to Chara it looks like a higher plant but is still in fact an algal species. Nitella has branches arranged in whorls around its stem. It can reproduce vegetatively and sexually. Stonewort’s look very similar to musk-grass but lack the skunky smell and has divided branches while musk-grass does not.
Nitella likes softer sediments and can grow in water up to nearly 30 feet deep. It can overwinter and begin to grow in early spring. Some species of stonewort’s, like starry stonewort (Nitellopsis obtusa), can reach extreme nuisance levels if left unconstrained. Starry stonewort has a distinguishable white bulb it produces in the sediment. This plant can be controlled through the use of biological, chemical, and physical control methods.
Coontail has long stems that actually lack true roots. The tip of the stem tends to look like a paintbrush because the leaves are closer together at the tip and also resembling the tail of a raccoon. The leaves of the plant are serrated are about 1-3 cm long. Coontail reproduces through male and female flowers and relies on the spread of its pollen. It can also grow through stem fragmentation. Coontail can grow to nuisance levels in ponds and lakes but the goal should always be to reduce it and not completely eliminate the plant. This plant has a tolerance for colder water and can deal with low light conditions.
These attributes allow coontail to overwinter and grow rapidly at the start of spring. Since the plant does not have roots and tends to live suspended in the water, it provides great habitat and can remove nutrients from the water column. In addition, because it can overwinter it also provides habitat for invertebrates and fish through the colder months when there not be as many plants growing as during the warmer months of the year. This plant can be controlled through the use of biological, chemical, and physical control methods.
Commonly known as common waterweed, this plant is widespread and found throughout most of the U.S. This plant has slim stems with leaves attached directly to the stem. The leaves surround the stem in a whorl of 3; this is important as there are other similar looking species that have leaves in whorls of 4 (Brazilian Elodea) or whorls of 5 (Hydrilla verticallata).
This plant has the ability to form dense mats and become a nuisance under certain environmental conditions despite being a native plant. Elodea has male and female flowers and reproduces through releasing pollen and through fragmentation. It can be found in a range of depths from ankle deep to around 15 feet of water. This plant can overwinter and actually still photosynthesize underneath ice. This provides it with a competitive advantage at the start of spring. Flowers are produced around the middle of summer. In Europe where it is non-native, this plant is considered to be an extreme nuisance. This plant can be controlled through the use of biological, chemical, and physical control methods.
Slender pondweed is a submersed aquatic perennial weed with narrow, ribbon-like leaves that often forms thick mats, especially in shallow water. Slender pondweed is found in lakes and ponds throughout the United States and is in the potamogetonaceae (leaf possesses a midvein) family. The preference habitat is full or partial sun, clear shallow water that is relatively warm, and a muddy or silty bottom. The water should be stagnant or slow-moving.
This pondweed can establish itself in more shallow water than many other pondweeds. It sometimes spreads aggressively. This aquatic plant forms branched leafy stems up to 3′ long. Alternate leaves are spaced about an inch and a half apart apart along the stems, becoming more crowded toward their tips. Both the stems and leaves are soft and flexible. Slender pondweed produces flowers in considerable abundance that are often held slightly above the water surface. The root system is fibrous and this plant reproduces vegetatively by the breakage of leafy stems that can form roots in the mud. It also reseeds itself. This plant can be controlled through the use of biological, chemical, and physical control methods.
Largeleaf pondweed is a submerged plant in the potamogetonaceae (leaf possesses a midvein) family and is native to the northeast. It has full-bodied robust stems and dimorphic (two types) leaves, one floating type and one submerged type. The submerged leaves look folded and bent along the middle of the leaf, and usually have over 25 veins. The floating leaves are an oval shape with a slightly pointed tip. Both types of leaves have a large stipule, tissue appendage that is attached at the base of the leaf stalk on the stem, that can grow up to 4.5 inches.
It is a great plant for fish habitat and prefers shallow water with soft sediments. It does not grow well in turbid waters and is susceptible to motor boats. This plant can sprout out new shoots through its rhizomes and flowers and fruits by the mid to late summer. This plant should be conserved in an aquatic system due to its value to the aquatic community, but if it grows to become a nuisance it can be controlled through chemical, biological, or physical methods.
Sago pondweed is a submerged aquatic plant in the potamogetonaceae (leaf possesses a midvein) family native to the northeast. The leaves of this plant have narrow leaves that can reach around 4 inches in length and resemble pine needles. Like largeleaf pondweed, sago pondweed can sprout from rhizomes. Each branch of leaves can be divided many times making the branches of leaves appear to be broad. The flowers and fruits of this plant are produced on a slim stalk that can either be submersed or floating.
They are spaced apart on the slim stalk and has a unique appearance. This plant is widespread, can grow in a variety of sediment types, and also has the ability to grow in extremely turbid water. Sago pondweed reproduces through its rhizomes and tubers which allow it to overwinter. This plant is considered to be of high importance as a food source for waterfowl and habitat for juvenile fish. This plant should be conserved in an aquatic system due to its value to the aquatic community, but if it grows to become a nuisance it can be controlled through chemical, biological, or physical methods.
Wild Celery also known as Eelgrass or Valliseneria is a submerged aquatic plant native to the northeast. This plant has ribbon like leaves with a defined middle stripe that emerge from a cluster of rhizomes under the sediment. Wild celery has both male and female flowers, but this plant can easily be identified when its female flowers develop.
The female flowers grow on a long white spiral stalk that develops underwater and then places the flower on the water’s surface. When fertilized, the female flower turns a capsular fruit that can reach up to 4.5 inches. It can overwinter via its rhizomes and tubers. Eelgrass can usually be found in firm substrates in a wide range of depths and can deal with turbid water. Waterfowl feed on every part of this plant and it offers exceptional fish habitat. This plant should be conserved in an aquatic system due to its value to the aquatic community, but if it grows to become a nuisance it can be controlled through chemical, biological, or physical methods.
Water stargrass is a submerged aquatic plant native to the northeast. It has slim freely branched stems that emerge from a rhizome in the sediment. It has alternate narrow leaves that attach directly to the stem. A big identifying characteristic is that it lacks a midvein, unlike all Potamogetons. By midsummer, water stargrass produces an unmistakable yellow flower that gives the plant its name; the flower looks like a star.
This is a hearty plant; it can handle varied water depths, can thrive in may sediment types, and can tolerate poor water quality. This plant should be conserved in an aquatic system due to its value to the aquatic community, but if it grows to become a nuisance it can be controlled through chemical, biological, or physical methods.
Variable leaf watermilfoil is a submerged aquatic plant native to the northeast that can grow to nuisance levels. The leaves of this plant can grow up to an inch and a half long, are divided like feathers, and are arranged in closely spaced whorls along the stem. The whorls are under 10 millimeters apart; which is a trait that distinguishes this milfoil from other species of watermilfoils. When in the water, the leaves look very bunched and rounded appearing like a cat’s tail. Variable leaf watermilfoil grows a flower that clusters in a spike and sticks out of the water. It prefers a variety of sediments and can grow in water up to 15 feet deep. It often will form large dense communities and can become a nuisance in regards to many recreational activities.
It reproduces through fragments which can grow into new plants and colonize areas, flowering depending on environmental conditions, and can overwinter via its rhizome. Although this plant can offer a lot ecologically in terms of food for waterfowl and fish habitat, when left unchecked in certain environments it can grow to a nuisance level and should be managed. This plant can be controlled through the use of biological, chemical, and physical control methods.
Small duckweed is a free floating plant native to the northeast. There are many varieties of duckweed including great, forked, or perennial. However, small duckweed is the most common and can be distinguished by its frond size and shape and its single root. It has round to oval shaped leaf clusters called fronds; each frond has one root and is stemless. Duckweed mainly reproduces via budding and has a microscopic flower. Duckweed receives all of its nutrition from the water column so it is limited to water heavy in nutrients. Since the plant is free floating, it is entirely at the will of the water and wind and does not depth or sediment dependent. It is most commonly found in protected coves or bays of ponds and lakes.
It survives the winter as small turions that lay on the sediment and then float to the surface in the spring. In the late summer, they lose buoyancy and sink to the bottom then go through their wintering process. It is a very nutritious food for waterfowl (as its name implies) and can remove large amounts of nutrients from the water. However, it can grow to be a massive nuisance in lakes and ponds. When left to grow unchecked it can completely carpet the water’s surface which can lead to negative impacts on submerged plants and deplete oxygen levels. Although this is a native plant to the northeast, it can exhibit properties of a nuisance invasive species and should be managed before it is allowed to become a major issue. Small duckweed can be controlled through pesticide treatments, biological controls like grass carp, and physical removal.
Watermeal is thought to be the tiniest seed-bearing plant in the world. It has no true stems or roots and often reproduces by budding, which allows it to establish itself in a waterbody very quickly. It is related to duckweed but is smaller than species of duckweed and lacks the roots found on duckweed. It is actually native to the northeast but due to its rapid reproductive capability it often grows to nuisance levels. Watermeal drifts with the wind and due to this, tends to build up in bays or coves in lakes and ponds. It is not reliant on depth or water clarity as it grows on the water surface. When submerged aquatic plants form canopies on the surface, it provides added habitat for watermeal. These canopies prevent the spread of watermeal through wind drift.
Watermeal produces buds that rest on the sediment through the winter and then float to the surface in the spring. It can often be found in conjunction with duckweed. Although this is a native plant to the northeast, it can exhibit properties of a nuisance invasive species and should be managed before it is allowed to become a major issue. Small duckweed can be controlled through pesticide treatments, biological controls like grass carp, and physical removal.
Common bladderwort is a floating aquatic plant native to the northeast. It has floating stems that can reach around 6 to 9 feet in length. The leaves of this plant grow right from the stem and are finely divided. The divisions look like filaments and fork out multiple times. Along these branches are the bladders, form which the plant gets its name, that allow the plant to float and trap prey. This plant is carnivorous! Aside from the unique bladders on the plant, bladderwort has a distinguished yellow flower that grows above the water’s surface. Bladderwort can grow multiple flowers along its stalk that is above the surface.
Bladderwort can survive in lakes, ponds, and bogs, but it is pH dependent and prefers neutral to acidic slow-moving water. This plant will overwinter via stem fragments and winter buds that grow late in the summer season. The plants sink to the bottom in the winter and as they decay the winter buds become detached. These buds then float up the water’s surface in the spring to develop into full plants. This plant is not dependent on sediment type as it floats on the surface; therefore, it can provide habitat for fish in areas where there may not be many other rooted aquatic plants. This plant should be conserved in an aquatic system due to its value to the aquatic community, but if it grows to become a nuisance it can be controlled through chemical, biological, or physical methods.
White water lily is a floating-leaf aquatic plant native to the northeast. White water lily has a stalk that grows out from a rhizome in the sediment with leaves that grow on the water’s surface, technically making it an emergent plant. The leaves are round with a notch on one end of the leaf and grow up to nearly a foot wide. The lobes on that side of the leaf are pointed which distinguishes it from other species of lilies. This plant grows beautiful white flowers that also grow on the water’s surface and have individual stalks arising from the plant’s rhizome. The flowers can grow up to nearly seven inches wide. Due to the long stalks that this plant grows, it prefers slow moving water that is about six feet and shallower. This plant primarily reproduces via flowering that occurs throughout the summer.
The flowers will open up during the morning and close in the afternoon. Once it is done blooming, the flower will go under the water’s surface and the fertilized seeds mature into a fleshy fruit. This plant should be conserved in an aquatic system due to its value to the aquatic community. However, if it grows to become a nuisance it can be controlled through chemical, biological, or physical methods.
Spatterdock, or bullhead lily or cow lily is a common floating leaf plant native to the northeast. Similar to white water lily, spatterdock leaves and flowers emerge directly from a large spongy rhizome making it an emergent plant. The rhizome of this plant looks like it came right out of an alien horror movie! The rhizome is marked with scars where the stalks of old leaf and flowers were attached. The leaves of spatterdock are heart shaped with rounded lobes, not pointed lobes like white water lily, and grow up to 10 inches long. This plant has a round yellow flower with five to six sepals that when closed look like a yellow golf ball. The flowers open in the morning and close at night. It prefers softer sediment and slow-moving water six feet and shallower.
Spatterdock reproduces via its flower and flowering occurs throughout the summer. Once fertilized, the sepals of the flower drop and the inner part of the flower develops into a fruit. Spatterdock has a significant ecological value; it anchors shallow water sediment, provides food for waterfowl and aquatic creatures, and offers shade and shelter for fish. This plant should be conserved in an aquatic system due to its value to the aquatic community. However, if it grows to become a nuisance it can be controlled through chemical, biological, or physical methods.
Water shield is a floating leaf aquatic plant that is native to the northeast. The stems and leaf stalks that are attached to a rhizome of the plant are flexible and allow the plant to bend in wind and wave action. The leaves are shaped like a football and are green on top and purple on the bottom. They have purple flowers that are about an inch wide that are above the water’s surface. One of the most characteristic traits of this plant is that the leaves have a gelatinous coat and feel slimy. There is evidence that this plant has properties making it toxic to other plants, so it is often found by itself or there is open water surrounding a community of water shield. When the leaves of water shield and lilies are younger they can often be confused with one another. A tell-tale sign to distinguish them is that the petiole from the main stem attaches to the central part of the football shaped leaf and there is no notch in the leaves like found in lilies. It prefers water around six feet in depth and shallower. Shoots grow in the spring from winter buds, seeds, or the rhizome.
Water shield produces its flowers in the early summer and relies on the wind for pollination. The male flower first develops and releases its pollen, and once the female flower is ready to receive the pollen it will rise above the water’s surface. This plant is consumed by waterfowl and can offer shade and habitat for fish and invertebrates. This plant should be conserved in an aquatic system due to its value to the aquatic community. However, if it grows to become a nuisance it can be controlled through chemical, biological, or physical methods.
Pickerelweed is a northeast native aquatic emergent plant, meaning that a portion of the plant is under the water while its vegetative part emerges past the water’s surface. This plant is often mistaken with arrowhead, another type of emergent aquatic plant. However, pickerelweed has more heat shaped leaves while arrowhead, as its name implies, has leaves in the shape of an arrow. The submersed portion of the plant has narrow leaves that look like blades of grass. One of the most distinguishing characteristics of this plant is its beautiful blue flower.
It has the ability to grow in water from a few inches to around 6 feet and prefers protected bays. Pickerelweed can reproduce through pollination and through its solid root system. This plant has rhizomes which are stems that grow horizontally under the ground and produce roots for another plant to grow. The rhizome system of pickerelweed can overwinter; this allows new clusters of leaves to form in the early spring. The flowers usually open up in early summer and are often frequented by bees. As is the case with most emergent aquatic plants, pickerelweed serves a number of ecological purposes. Pickerelweed acts as habitat for many insects including bees, food for waterfowl and muskrats, sheltered habitat for fish, and this plant aids in shoreline stabilization. This plant is often purposely planted by landscapers for its aesthetic appeal and ecological contribution. This plant should be conserved in an aquatic system due to its value to the aquatic community. However, if it grows to become a nuisance it can be controlled through chemical, biological, or physical methods.
Common arrowhead is an emergent plant native to the northeast. Like its name implies, it has distinguished deep arrow shaped leaves that look like the letter “A”. It is often mistaken with pickerelweed; however, pickerelweed has more heat shaped leaves. The leaves form a large cluster coming from a buried rhizome and can grow up to 15 inches long. The flowers grow along a stalk, are white in color, and have three rounded petals. This plant is found in shallow water under 3 feet in depth of lakes, ponds, streams, and wetland areas. It can tolerate a wide range of sediment types, overwinters via its rhizomes, and reproduces through seed and flowering.
Arrowhead has a high ecological value as it stabilizes shoreline, uptakes nutrients at a high rate, and offers habitat for young fish. This plant is often purposely planted by landscapers for its aesthetic appeal, ecological contributions, and ease of propagation. This plant should be conserved in an aquatic system due to its value to the aquatic community. However, if it grows to become a nuisance it can be controlled through chemical, biological, or physical methods.
Blue iris, or blue flag, is an emergent plant native to the northeast. The flower and leaves grow from a rhizome that is shallow in the sediment and sometimes even minorly exposed. The leaves grow in clusters and the flower stalks grow taller than the leaves, giving the plant a flag-like look. The flowers are blue, grow up to three inches wide, and have three petal-like lobes. There are many other species of iris that when not in flower can easily be mistaken for blue iris. Most of the other iris species are native to the northeast and offer similar ecological contributions as blue iris. There is also a non-native iris that has yellow flowers, but is not considered to be a nuisance plant. When the leaves of an iris and a cattail are young, they can often be mistaken for one another. A tell-tale way to tell them apart is that if you were to rub your hand down the length of the leaf, iris leaves have one keel while cattail leaves have two keels.
Blue Iris can overwinter via its rhizomes and reproduces through flowering. This plant is a great source of food for waterfowl, attracts bees (the flowers have a specific design that ensures cross pollination), and they stabilize shoreline. This plant is often purposely planted by landscapers for its aesthetic appeal, ecological contributions, and ease of propagation. This plant should be conserved in an aquatic system due to its value to the aquatic community. However, if it grows to become a nuisance it can be controlled through chemical, biological, or physical methods.
Eurasian watermilfoil is an invasive submerged aquatic plant originally from Europe and Asia. The plant’s range now reaches throughout most of the continental U.S. It is one of the “poster children” for aquatic invasive species and often is seen on billboards or handouts. The plant can grow to over 6 feet in length and often creates a canopy on the water’s surface. The leaves are in whorls of 4 around the stem. Eurasian watermilfoil is at a competitive advantage against other plants because it can grow in water up to 20 feet deep, can tolerate cold water, and can reproduce rapidly through fragmentation. Growing 20 feet deep in the water provides this plant a habitat that most others cannot withstand. Tolerating cold water allows this plant to start growing before other aquatic plants in a system (sometimes it even overwinters). This sequentially can create a dense canopy shading out the water column and not permitting other plants to photosynthesize to their fullest potential.
Reproducing through fragmentation grants the ability for a single stem or leaf to take root somewhere and establish a new colony. These traits of the plant although spectacular, make it a massive issue for lakes and ponds outside of its native range. The best way to stop this plant from spreading still lies in prevention and unfortunately, many lakes and ponds are already infected with this nuisance plant. Eurasian watermilfoil can be controlled through the use of aquatic herbicides; there are some biological and physical control methods that can be effective as well.
Also known as fanwort, this plant is native to the south and is often introduced through the aquarium industry. Fanwort grows through extreme root growth or shoot fragments. It is usually found in shallow water but if water clarity is high can grow up do depths of 30 feet. It has two opposite leaves with a petiole that branches off of the main stem. If it grows tall enough it will develop floating leaves that are alternate and ovately shaped and can form a dense canopy on the water’s surface. Fanwort prefers acidic waters (pH 4-6) and can withstand flowing water; giving this plant a competitive advantage in certain habitats.
This plant primarily grows through fragmentation which makes it spread very quickly in flowing waters as fragments can easily be carried downstream. It also reproduces sexually via flowering. Control strategies for this plant include drawdown, addition of lime to increase pH (viable in smaller bodies of water), grass carp, and chemical control.
Curly leaf pondweed (CLP) is an invasive submerged aquatic plant in the potamogetonaceae family (leaf possesses a midvein) from Europe and was first documented in the U.S. in the mid 1800’s; it is now spread throughout most of the continental U.S. CLP is an early season grower, even having the ability to grow under ice, and can reach the surface of the water by June. Due to its ability to grow under ice it can provide needed habitat for fish and invertebrates during the winter months. It usually dies back by the middle of July unlike most aquatic plants which grow into September. Dying in the middle of July can present an ecological problem for lakes and ponds. Once all the CLP dies off, it releases a high amount of nutrients that can result in algal blooms. As the name describes, this plant has very curly leaves. The leaves are serrated and are very distinctive in appearance. CLP is a member of the Potamogeton family otherwise known as pondweeds. Some pondweeds produce floating leaves in addition to their submersed leaves; CLP is not one of those plants. In the spring CLP produces flower spikes that grow above the surface of the water. This plant primarily produces through a structure known as a turion. A turion is a bud that overwinters and detaches from the plant remaining in the sediment.
This structure makes control of this plant extremely difficult because even if the plant is harmed or killed, the turions remain in the sediment. However, many studies have shown that multiple early season herbicide treatments not only kill the plant but hinder the spread of turions as well. This plant can be controlled through the use of biological, chemical, and physical control methods.
Brazilian Elodea (Egeria) is an invasive submerged plant native to South America. Like fanwort, it is common in the aquarium trade. It is also commonly mistaken with Hydrilla and the northeast native Elodea. Brazilian elodea has leaves in whorls of 4-6, Hydrilla has toothed leaves in whorls of 5, and the northeast native Elodea has leaves in whorls of 3. Although they may look similar at first, these characters make them distinguishable.
Similar to Eurasian watermilfoil, this plant can withstand low light and low temperature conditions giving up a leg up on many other aquatic plants. The stems of the plant are very branched and in low light can reach over 20 feet in length. If given the chance, this plant will form a dense canopy on the water’s surface. The leaves at the tip of the plant are densely packed and nearly indistinguishable but the leaves are more widely spread on the main part of the stem. This plant mainly grows through vegetative propagules of its stems, branches, and root crowns. It can also grow swiftly at up to a half inch a day. Control strategies for this plant include drawdown, grass carp, and chemical control.
Hydrilla is a submerged plant from Asia that was first reported in the United States in Florida in the late 1950’s. There are two types of hydrilla found in the US, monoecious and dioecious. The monoecious type has both male and female flowers while the dioecious type only bears a male or a female flower. There is good reason to believe that this plant was also partially introduced through the aquarium trade. The factors that most often restrict its growth and spread are water depth and water velocity. Leaves are densely packed along the stem and can grow up to an inch in a day. On the underside of the leaf, the midrib has one or more sharp teeth and the leaves themselves are serrated. The leaves are attached directly to the stem and are usually found in whorls of five. It appears very similar to Elodea and Brazilian elodea but can be distinguished through its whorls of 5 leaves, serrated leaf edges, and it is the only one of the three to produce tubers or turions.
Dioecious hydrilla can only spread through fragmentation as it does not produce seeds and its tubers and turions. Monoecious hydrilla can reproduce through seed and flower. Control methods for this plant include grass carp, chemical treatments, and drawdown to kill the vegetative part of the plant; tubers and turions may survive the winter and sprout into new plants the following spring.
Water hyacinth is an invasive floating plant native to South America and is now widespread throughout the tropical climate of the world. It is believed it was first introduced to the United States as an ornamental plant in the late 1800’s. It does not deal well with cold weather areas and tends to not establish long standing populations in the northeast. As a floating plant it is apt to deal with turbid water. The leaves are very thick with a heart shaped base and glossy in appearance. The petiole of water hyacinth is very spongy and each leaf attach to one another at the base of their petiole. Water hyacinth has distinguished long feathery roots that hang beneath the cluster of leaves. It has a short lived exuberant purple flower with yellow spots on its top petal. Water hyacinth reproduces by seed and vegetatively. Seed reproduction is specifically important in temperate climates.
The leaves can be killed in colder temperature and the population therefore depends on a seed bank. The only environmental conditions that limit water hyacinth’s growth is temperature and nutrient availability, making this plant a serious nuisance in certain areas. Control methods for this plant include prevention from introduction, physical removal via hand pulling or harvesting, and chemical treatments.
Mosquito fern also known as Azolla, is an aquatic free-floating fern native to the state of Florida. The leaves of this plant overlap and give it a quilted appearance and it has a single root on each stem. This plant prefers habitats of slow-moving ponds or quit coves. Mosquito fern can invade a waterbody quickly and can often be found in combination with duckweed and watermeal. Like duckweed and watermeal, this plant provides habitat for vertebrates and invertebrates but when left unchecked and allowed to grow uncontrollably, can carpet the water’s surface and lead to oxygen depletion.
This plant has a symbiotic relationship with a cyanobacteria species; the cyanobacteria species resides safely on the fern and supplies the plant with excess nitrogen to boost plant growth. Mosquito fern primarily reproduces through budding. Control methods for this plant include prevention of introduction, chemical treatments, and physical removal via hand pulling, harvesting, or surface skimming.
Waterlettuce is a floating invasive plant in the northeast that is considered to be native to the southeast US, South America, and Africa. It is not as productive and fast growing as water hyacinth but still has the ability to grow rapidly and double its population in a few weeks; making it a common nuisance species that covers the surface of occupied waters. The leaves of waterlettuce look similar to a scallop shell with their heavy waves. The leaves are thick, covered in tiny hairs, and are water repellent. Similar to water hyacinth, leaves are attached to one another at the plant’s base to form a free-floating cluster.
An easy distinguishing feature of waterlettuce is its white to tan colored roots compared to the black or brown roots of water hyacinth. Cold temperatures will kill the leaves of waterlettuce in colder climates. It spreads through vegetative reproduction and seed dispersal. Northern populations of this plant depend on seed banks as the cold winter can kill the vegetative part of the plant. The rapid growth in the warmer months is mainly due to vegetative reproduction. Control methods for this plant include prevention from introduction, physical removal via hand pulling or harvesting, and chemical treatments.
Water chestnut is a plant native to Eurasia and Africa and brought to the northeast U.S. in the late 1880’s. This plant is one of the most distinct in appearance in most of North America. It prefers slow moving shallow water, nutrient rich sediment, and can survive in brackish water. Water chestnut grows very aggressively and can over take a system; to the point where it can be difficult to ascertain where water begins from land.
This plant has dimorphic (two types) leaves; the submersed leaves are feather like and resemble milfoil leaves in appearance. They can grow up to 4 inches long and are attached to the stem in a whorl. The floating leaves are much more distinct. The floating leaves form a rosette that can be up 1 foot in diameter. The individual leaves are shaped like a triangle, have wide serrations, and are a light green color.
One of these plants most distinguishable characters are its pronged nutlets that are known to be a huge impediment on recreation (they hurt a lot!!!). Small white flowers are produced on the rosette sometime in June and later mature into the nutlets. Each rosette of water chestnut can produce around 10-15 nutlets which can be viable for 8 to 15 years in the sediment and the daughter nutlet itself can produce multiple rosettes. Therefore, it is of the utmost importance to begin removing this plant as soon as it is discovered in a waterbody. Otherwise, the persistent viable nutlets will remain for the 8 to 15 years. This plant hinders many recreational activities like swimming, boating, and fishing and can have ecological impacts like increasing the rate of eutrophication, reducing habitat and light availability for desirable plants, and reducing concentrations of dissolved oxygen. Control methods for this plant include prevention of introduction, immediate removal following detection, chemical treatments, or physical removal via harvesting or hand pulling (best to be done before August so that rosettes cannot drop their nutlets).
Cattails are wetland plants with a unique flowering spike and flat blade like leaves that reach heights from 3 to 10 feet. They are one of the most common plants in marshes and on the edge of lakes and ponds. In our area there are two species of cattails, one northeast native and one invasive. The two different species can hybridize together and under certain conditions cattails can grow and spread in a vigorous manner. The pollinated flowers of this plant develop into fluffy seed heads that appear like a cat’s tail. The seeds blow across ponds rapidly. Just as common, cattails spread through their strong root system. The thick white roots also known as rhizomes, grow underground near the edge of the water. The dense foliage and debris from old growth cattails makes it very difficult for competing plant species to grow. They prefer shallow flooded conditions and can easily establish themselves along a shoreline. When unimpeded, cattail stands will expand and can extend their rhizomes well out into a pond surface, actually floating above much deeper waters.
They are often viewed as a nuisance because they grow in such think stands and block the view of open water. They are best controlled through herbicides and cutting. The herbicides work best when applied in the fall as this is when cattails are sending nutrients down to their roots to prepare for the winter. This effectively sends the herbicide down to the roots as well providing a higher probability of plant death. Cutting is more of a maintenance technique because it does not remove the root system.
Common reed, more commonly referred to its Latin name Phragmites, is an emergent aquatic plant. In our area there are two species of Phragmites, one northeast native and one invasive both of which exhibit nuisance properties. The two different species can hybridize together. Phragmites forms incredibly dense stands and can grow to a height of 15 feet. With how dense it can grow and its unbelievable height, this plant is often a nuisance around lakes and ponds. Like cattails and pickerelweed, this plant has a rhizome system. A defining characteristic are the cluster of spikelets, which possess reproductive structures, at the top of the plant that look like “feather dusters”. The leaf of Phragmites are blue-green in color and can be up to 20 inches in length. It most often grows along wet shores of disturbed sites and can live in water 6 feet deep. It overwinters by making buds on its rhizomes during the summer that remain dormant until the spring. Once it warms up, the plant will shoot up. It also reproduces through seeds on the spikelet but most commonly through its rhizomes.
The rhizomes of this plant allow it to grow at such a high density and is a core reason why it can reach nuisance levels. They are best controlled through herbicides and cutting. The herbicides work best when applied in the fall as this is when Phragmites (like cattails) are sending nutrients down to their roots to prepare for the winter. This effectively sends the herbicide down to the roots as well providing a higher probability of plant death. Cutting is more of a maintenance technique because it does not remove the root system.
Grass carp: A fish to be stocked that is a natural herbivore and assists in long term control of nuisance plants
Insects: Depending on the species of the plant, there are certain insects that can be introduced to assist in long term control of plants
Aquatic plantings: Establishing plant communities of desirable species
Aquatic dyes: Dye that blocks out sunlight from plants and limits their ability to photosynthesize
Herbicides and algaecides: Chemical formulations made to target specific plants. Some herbicides are selective and some are not; a state certified pesticide operator makes the decision on what herbicides to use based on goals, target plants, and any additional details of the lake or pond
Benthic barriers: Large mat made of a number of materials that is laid on the lake bottom on top of plants and inhibiting their growth
Dredging: Physical removal of sediment from a lake. Dredging can also remove plants themselves as well as reproductive structures like seeds, tubers, and turions
Drawdown: Lowering of water level during the winter months allowing plants to freeze and die. Only works if a proper dam is on site and depends on the biology of the target plants
Harvesting/cutting: Removal of plants through the use of heavy machinery. Harvesting collects the plants to be taken off site and cutting only cuts the plants leaving fragments in the pond or lake
