Brazilian elodea, also known as Brazilian waterweed, is a submerged aquatic plant in the waterweed (Elodea) family. It can be found in a wide range of freshwater habitat types, including wetlands, lakes, ponds, and even slow-flowing streams. While it is usually rooted at depths of 1-2 m, it can be found in up to 6 m of water, and can also drift freely. Optimal temperatures for growth are 16-20°C, but it also has the ability to overwinter under the ice. In its introduced range, this species displays vegetative reproduction only, meaning that small fragments break off to form new plants. Because of this, it can spread quickly. This species has become a popular aquarium and water garden plant, often sold under the alias “Anacharis”.How to Identify- Often confused with Hydrilla, another invasive species in the US and prohibited under the ISA, 2015.- Is more likely to be confused with the native aquatic plant, Canada Waterweed (Elodea canadensis).- Plant grows submerged in depths ranging from 1-2 m (3.3-6.6 ft), but can grow in depths up to 6 m (19.7 ft).- Stems are thin (1 – 3 mm (0.04 – 0.12 in) in diameter) upright, cylindrical, simple or branched, and grow to the surface of the water forming dense mats.Leaves are 1 – 3 cm (0.4 – 1.2 in) long, up to 5 mm (0.2 in) broad, and found in whorls of 4 to 8.- Leaves and stems are generally bright green and the short internodes give it a very leafy appearance.- Brazilian elodea has small flowers with three white petals that stick out approximately 2 cm (0.8 in) above the surface of the water, once they open.
Eurasian water-milfoil is an invasive aquatic plant native to Europe, Asia, and northern Africa. Introduced to North America in the 19th century, it is now one of the most widely distributed invasive aquatic plants on the continent. It is suspected to have been introduced via ballast water, but was then moved around within the province through recreational watercrafts and natural expansion.Eurasian water-milfoil prefers shallow water 1-3 m (3.3 – 9.8 ft) deep, but can root in up to 10 m (32.8 ft) of water. Being a fast-growing perennial, it forms dense underwater mats that shade out other aquatic plants. When large stands begin to die off in the fall, the decaying plants can reduce oxygen levels in the water, potentially affecting the fish communities.The plant can hybridize with our native milfoil, northern water milfoil (Myriophyllum sibericum), creating a more aggressive form of the invasive species. Because tiny plant pieces can develop into new plants, Eurasian water-milfoil is easily spread when water currents, boat propellers, trailers, or fishing gear carry plant fragments to new areas.How to Identify- The plant is a perennial that grows under the water surface.- Feather-like green leaves circle the stem in groups of four or five.- Leaves have 12 or more thread-like segments.- Tiny, reddish flowers grow on spikes 5 – 20 cm (2 – 7.9 in) long that rise above the water towards late summer (August-September).- Eurasian water-milfoil looks similar to two other aquatic plants: the native northern water-milfoil (Myriophyllum sibiricum) has leaves with 11 or fewer leaf segments.- Whereas, the invasive parrot feather (Myriophyllum aquaticum) has not been found in the wild in Ontario.
European frog-bit is an invasive aquatic plant native to Europe and parts of Asia and Africa. In 1932, the plant was brought from Europe to the Central Experimental Farm in Ottawa for possible commercial use as an ornamental plant. In 1939, it was found in the Rideau Canal. Since then, it has spread to several rivers, Lake Ontario, Lake Erie, and other inland waters. European frog-bit grows rapidly and forms dense, floating mats. It can be found in slow-moving waters, such as sheltered inlets, ponds, slow-running rivers, and ditches. Large areas of frog-bit that die in the fall and decompose may lead to reduced oxygen levels in the water that can affect aquatic life. New plants can grow from stem fragments, seeds, and winter buds known as turions that can be spread to new waters by boats and wildlife.How to Identify- The plant can float free or put down roots up to 50 cm (1.6 ft) long in shallow water.- It produces a single white flower up to 2 cm (0.8 in) wide with three rounded petals and a yellow centre.- Leaves are 2.5 – 5 cm (1 – 2 in) wide – about the size of a Canadian one-dollar coin – and round to heart-shaped. They form a rosette up to 6 cm (2.4 in) wide.- The leaf bottom is purple-red with a spongy coating along the middle vein of the leaf that allows it to float on the water.European frog-bit looks similar to other native aquatic plants, including North American frog-bit (Limnobium spongia), watershield (Brasenia schreberi), and white water lily (Nymphaea odorata). North American frog-bit leaves have a spongy coating covering the entire bottom of the leaf. Watershield leaves do not form a rosette and the leaves and stems under water have a slimy coating. Mature white water lily leaves are round and much larger – 15 to 30 cm across.
European water chestnut (or water chestnut) is an invasive aquatic plant that has been introduced to the Ottawa River in eastern Ontario within Voyageur Provincial Park. It has also been found at Wolfe Island in Lake Ontario, in the Rideau River in Ottawa, and in the St. Lawrence River in Kingston. The plant is native to Europe, Asia, and Africa, and is used in North America as an ornamental water garden plant. Although it’s not certain how the plants arrived in Ontario, it was most likely introduced through the improper release of water garden plants.How to IdentifyWater chestnut populations in the Ottawa River, as well as neighbouring provinces and states, have become a serious nuisance causing a number of impacts, including:- Forms extremely dense floating mats of vegetation that shade out native vegetation, decreasing plant biodiversity and making recreational activities like swimming, angling, and boating almost impossible in the infested areas.- The hard nuts with sharp, barbed spines can accumulate on shore and cause injury when stepped on.- Reduced light penetration and plant growth beneath the water chestnut canopy, combined with a large amount of decomposing vegetation below, can lead to decreased dissolved oxygen levels, which can impact native species and cause fish deaths.Since water chestnut populations occur only in a few locations in Ontario, it is important that we put every effort towards removing this plant before it spreads to other locations. The Ministry of Natural Resources and Forestry, with support from partnering agencies, are working to eradicate water chestnut from the Ottawa River by pulling the plants by hand, with rakes, and mechanical harvesters. Efforts to control this new invader are ongoing.
Fanwort is an invasive aquatic plant native to the southeastern United States and parts of South America. Today, it has invaded parts of the Crowe River watershed in central Ontario, as well as waters in the northern United States, Asia, and Australia. Since fanwort is a popular aquarium plant, it may have been introduced to Ontario by someone emptying the contents of an aquarium into a waterway, or boats may have carried plant fragments from an infested area outside the province. Fanwort grows and spreads aggressively, forming dense mats under or at the surface of the water. It is most often found in slow moving or stagnant water less than 3 m (9.8 ft) deep. The plant can tolerate cold temperatures and stay green throughout the year. It prefers acidic water with a pH of about 4.8 to 7.8.How to Identify- Fanwort is a submerged plant that roots on the bottom of lakes and rivers.- Under the water, pairs of finely divided fan-shaped leaves grow on opposite sides of the main stem, creating a feathery effect.- The plants also have small, floating oblong leaves up to 3 cm (1.2 in) long.- Fanwort flowers from late spring to early fall. The flowers usually rise above the surface of the water. They are 0.6 – 1.5 cm (0.2 – 0.6 in) wide and white to pale yellow, sometimes with a purple or pink tinge.Fanwort looks similar to other aquatic plants, including bladderwort (Utricularia vulgaris), white-water crowfoot (Ranunculus aquatilis), northern water-milfoil (Myriophyllum sibiricum), water marigold (Megalodonta beckii), and coontail (Ceratophyllum demersum). Only fanwort has opposite, finely divided, fan-shaped leaves on distinct stems.
Floating primrose-willow is an herbaceous perennial aquatic plant native to South America, Central America, and the southeastern United States. It is a popular ornamental and water garden plant that can outcompete native plants and take over aquatic ecosystems when released into the wild or spread to a new areas. How to Identify- Leaves are smooth, green, and arranged in an alternate pattern. Leaves can be in one of two shapes: early growth leaves are rounder, while mature leaves are oval. - Flowers are a strong yellow colour with five petals. - Stems are reddish to brown and can be up to 3 metres (9 ft 10.11 in) long. - Roots form at the nodes of the stem and can reach downward into the substrate.
Flowering rush is a perennial aquatic plant native to Eurasia and Africa that grows in lakes, riparian zones, wetlands, and marshes. It was first brought to North America from Europe in the 1800’s as an ornamental plant for ponds and water gardens.Once it becomes established, it can out-compete native vegetation and create dense colonies that hinder recreational activities, such as boating, fishing, and swimming. It can spread between waterbodies via dispersal of seeds, rhizome fragments, and bulbils transported with boats, boat trailers, and other equipment. One risk is that any piece of the plant is capable of growing into a new plant.How to Identify- Numerous flowers on an erect, leafless flowering stalk over 1.5 m (4.9 ft) tall.- Flowers are stalked, emergent, and pink in colour with 3 sepals and 3 petals. 2 – 2.5 cm (0.8 – 1 in)wide.- Leaves are erect, floating, or submersed. 5 – 10 mm (0.2 – 0.4 in) wide, up to 2.7 m (8.9 ft) long.
Hydrilla is an aquatic plant that has spread rapidly through much of the United States. Hydrilla’s native range is unknown, however, some scientists say the plant is native to Asia; others say Africa or Australia. Hydrilla was introduced to North America in the early 1950s when it was brought to the southern United States for use as an aquarium plant. It spread into waterways when people emptied their aquariums into lakes or rivers. Hydrilla is highly adaptable and it thrives in still and flowing waters, including rivers, lakes, ponds, wetlands, streams, and wet ditches, as well as in a range of nutrient and light conditions. The plant grows up to 2.5 cm (1 in) a day. It has a competitive advantage over many native plants because it begins converting sunlight to energy that helps it grow (the process known as photosynthesis) earlier in the day than most plants. Because tiny plant pieces can develop into new plants, hydrilla is easily spread when water currents, boat propellers, trailers, fishing gear, or people carry plants or plant fragments to new areas.How to Identify- The plant is a perennial that grows underwater.- Stems are rooted, erect, either branched or unbranched, and grow up to 7.5 m (24.6 ft) long.- Leaves are green, attached to the stem and arranged in whorls of 3 to 8. They have visibly saw-toothed edges, and sometimes have prickles on the underside.- Flowers are small, with petals 2 – 4 mm (0.1 – 0.2 in) wide, and are white to reddish or white to light green with red stripes. When open they float on the surface of the water.
Invasive Phragmites (European Common Reed) is an invasive plant causing damage to Ontario’s biodiversity, wetlands and beaches. Invasive Phragmites is a perennial grass that has been damaging ecosystems in Ontario for decades. It is not clear how it was transported to North America from its native home in Eurasia.Invasive Phragmites is an aggressive plant that spreads quickly and out-competes native species for water and nutrients. It releases toxins from its roots into the soil to hinder the growth of and kill surrounding plants. While it prefers areas of standing water, its roots can grow to extreme lengths, allowing it to survive in relatively dry areas.How to IdentifyOne factor making the identification of invasive Phragmites difficult is the existence of a closely related native subspecies. Generally, native Phragmites does not grow as tall as the invasive plant and does not out-compete other native species. A number of characteristics of the plant can be useful in distinguishing between the native variety and invasive Phragmites. The following information can help in identifying invasive Phragmites.Invasive Phragmites: - Grows in stands that can be extremely dense with as many as 200 stems per square metre.- Can grow so densely that it crowds out other species.- Can reach heights of up to 5 metres (15 feet).- Has stems that are tan or beige in colour with blue-green leaves and large, dense seedheads.Native Phragmites: - Grows in stands that are usually not as dense as the invasive plant;- Well-established stands are frequently mixed with other plants; and- Usually has more reddish-brown stems, yellow-green leaves and smaller, sparser seedheads.
Oxygen weed is a perennial, submerged aquatic plant native to South Africa that is popular in the aquarium and pond scaping industries. It can grow in dense floating mats that can outcompete native aquatic plants and remove fish and invertebrate habitat.How to Identify- Submerged perennial that appears dark green with spiraling leaves that have minute serrations along the edges, leaves curl strongly downward and back up. - Stems can grow 6.5 m (20 ft) long and create mats 1 m (3 ft) thick. - Similar in appearance to hydrilla and Elodea species
Parrot feather is an invasive perennial aquatic plant native to South America. It was introduced to North America around 1890 as an aquarium and aquatic garden plant. Due to intentional and accidental releases, it was able to escape into waterways and spread by plant fragments. Parrot feather is limited to non-tidal waters, including lakes, ponds, and slow-moving streams. The populations found in North America are female plants, and as a result, can only reproduce vegetatively.How to Identify- Herbaceous, submerged aquatic plant reaching 2 to 5 m.- Leaves are whorled and feather-like with 20 to 30 segments per leaf.- Submerged leaves are 1.5 – 3.5 cm (0.6 – 1.4 in) long and emergent leaves are 2 – 5 cm (0.8 – 2 in) long and much greener.- Flowers in axils of emergent leaves, forming a terminal spike above water.- Only female white flowers are known to occur in North America.
Starry stonewort is an invasive macroalgae native to northern Eurasia. It was introduced in North America through the St.Lawrence River in 1974 and was first identified in Ontario in 2009 in Presqu’ile Bay as well as Lake Simcoe. Ballast water is the suspected method of entry and subsequent spread through the Great Lakes basin.Starry stonewort forms dense mats in waters two to 10 meters in depth. Its white bulbils (seed-like structures) are deposited in the mud, allowing the species to be easily spread and to survive Ontario’s cold winters.In North America, only male individuals of starry stonewort have been recorded. They have no roots, making them easy to spread to new areas. The species is spread primarily by boating, but it is suspected that species like waterfowl can transport fragments to other unconnected water bodies as well.How to Identify- It is a macroalgae that resembles true plants with thin stems and branchlets similar to thick fishing line.- Whorls of 4-6 branchlets coming off the main shoots, with blunt tips.- White, star-shaped bulbils, which give the species its name, are produced at the nodes, generally 3-6 mm (0.1 – 0.2 in) wide.- Can form dense mats up to 3 m (9.8 ft) thick.
The genus Azolla includes seven species of aquatic floating ferns such as large mosquitofern (A. filiculoides) Carolinian mosquitofern (A. caroliana), and feathered mosquitofern (A. pinnata). Azolla spp. reproduce vegetatively when fragments from the main axis break off. Azolla spp. can fix nitrogen through a symbiotic relationship with cyanobacteria, which is why it is often used to aid in fertilizing rice paddies in southeast Asia.How to Identify- Individual plants are small and consist of a short, branched, floating stem with alternatively arranged leaves. - Reduced in form, do not represent typical “ferns” but rather resemble duckweed or mosses. - Some species have a reddish colour to their leaves, giving a striking red colour to the surface of waterbodies they have infested.
Water hyacinth is a free-floating, aquatic plant in the pickerel-weed family (Pontederiaceae spp.) imported into North America in 1884 for an exposition in New Orleans. New introductions are probably the result of improper disposal of pond plants or when ponds adjacent to local waterbodies become flooded. Water hyacinth is readily available ornamental plant for purchase that is typically put in ponds and outdoor water gardens in Ontario, where it is not a regulated species.How to Identify- Leaves are floating or emergent and form a rosette.- Leaf blades are bright green, thick and glossy, egg-shaped to round, and on an inflated leafstalk that is filled with spongy tissue.- Roots are fibrous, dark purple/black, and hang beneath the rosette.- Flowers are loosely clustered with 4 to 15 flowers on a spike above the rosette. Flowers have six blue-violet petals with one petal being deeper violet with a yellow spot.- Fruit is a capsule with many seeds.Stolons extend outward from the parent plant to produce new plants.
Water lettuce is a free-floating aquatic plant whose origins are uncertain. An explorer in Florida, during the 18th century was the first person to record its presence in North America. Some experts believe it is native to the southeastern United States, while others believe it came from Africa, southern Asia, or South America. It was likely moved beyond its native range by those wishing to plant it in their water gardens, aquariums, and ponds. Water lettuce is a prohibited plant in Florida, Louisiana, Mississippi, and Texas, and is considered a noxious weed in South Carolina and Delaware.Water lettuce forms large, dense floating mats. The plant can adapt to life in ponds, lakes, and quiet areas of rivers and streams, but cannot withstand saline environments (salt water). While not usually able to tolerate cold temperatures, several populations of water lettuce have been observed in Ontario, and they may be successfully reproducing. Scientists are currently studying where water lettuce is growing in Ontario, whether it is able to survive Ontario’s winters, and whether it is likely to spread.How to Identify- The free-floating plant forms a rosette or group of leaves arranged in a circle that resembles an open head of lettuce.- Thick, ridged leaves are 2 – 20 cm (0.8 – 7.9 in) long and light green, with short, white hairs, rounded ends and no stems.- Flowers are small and white to pale green.The plant produces a green berry that turns brown at maturity.- Many feathery roots 50 – 80 cm (1.6 – 2.6 ft) long hang under the rosette of leaves.- Large numbers of plants may be connected by underwater runners, called stolons.
Water soldier is an invasive aquatic perennial plant that is native to Europe and Northwest Asia. The populations that occur in Ontario are within the Trent-Severn Waterway, the Black River (near Sutton, ON) and in Red Horse Lake north of Gananoque. Prior to being regulated as a prohibited invasive species under Ontario’s Invasive Species Act, water soldier was sold for use as an ornamental plant in water gardens, which is the most likely source of its introduction to the wild.How to Identify- It is a submerged aquatic plant, which becomes buoyant during the summer months. As the leaves mature, they become waterlogged and the plant sinks below the water’s surface.- Leaves can reach up to 40 cm (1.3 ft) long, are sword-shaped, bright green, with sharp spines, and form a large ‘rosette’ or group of leaves arranged in a circle.- Flowers, if present, are white with three petals. Flowering of water soldier is exceptionally rare in Ontario, so this should not be used as a main identification characteristic.- Roots can be lightly rooted, but are not always attached to the mud at the bottom.- Plants can be found growing in depths of up to 5 m (16 ft).- Mature water soldier plants produce offsets or clones, which are similar to those produced by the household spider plant.Water soldier is similar in appearance to an aloe plant, household spider plant, or the top of a pineapple. Water soldier may be confused with other aquatic plants in Ontario, such as native bur-reeds, arrowheads, or eel-grass. However, none of these plants have serrated leaf edges, which can be used to easily distinguish water soldier from these other aquatic plants.
The genus Salvinia includes twelve species such as S. molesta, S. auriculata, S. minima, and S. natans, which are small, floating, aquatic ferns native to warm tropical regions of the world, including Central and South America. S. natans, or floating watermoss, is native to Africa, Asia, and Europe. They are most used in North America in the water garden and aquarium trade. Salvinia species grow in open and still waters, flood canals, and other waterbodies and prefer full sunlight, warm, and nutrient rich waterbodies. When giant salvinia (S. molesta) was first introduced as an ornamental aquatic plant to California, it spread quickly to new waterbodies on boats and fishing gear. Salvinia species pose a significant threat to freshwater ecosystems as they can grow rapidly across water surfaces, forming dense floating mats that cut off light to other aquatic plants, reduce oxygen content and degrade water quality for fishes and other aquatic organisms. Because of its impact, giant salvinia is regulated in the US on the Federal Noxious Weed List. How to Identify-Free floating aquatic ferns with horizontal stems that float just below the surface. - Leaves have hairs on the surface, and young leaves lie flat on the water while mature leaves are forced upright forming a long chain as the plant develops to create mats. - Underwater root structure conceals stalks that can have infertile egg-shaped spore cases.
Yellow floating-heart is a perennial aquatic plant native to Asia and Europe. Introduced to North America in the late 19th century, it has been used as an ornamental plant in outdoor gardens. Since its introduction, accidental and intentional releases as well as flooding have led to its dispersal into other waterways.Yellow floating-heart is most commonly found in slow moving waters, about 0.5 to 4 m (1.6 – 13 ft) deep, such as rivers, lakes, or ponds. Its ability to reproduce by broken stems and seeds as well as its availability to be purchased online makes it a species that can be easily introduced.How to Identify- Aquatic, bottom-rooted perennial plant.- Stems are long and branched, reaching up to 1 m (3.3 ft) or more, located below the surface of the water.- Leaves are circular or heart shaped and about 3 – 10 cm (1.2 – 3.9 in).- Flowers consist of five bright yellow petals.- Seed capsules contain numerous flat, oval seeds.
Yellow iris, or yellow flag iris, is a perennial aquatic plant native to Europe, Western Asia, and North Africa. It was first introduced to North America in the 19th century as an ornamental plant for ponds and water gardens. The plant has since spread to many waterways, including those in parts of Southern Ontario. In addition to its use in gardens, it has been planted in wastewater ponds because of its ability to absorb heavy metals.Yellow iris can grow in wetlands, along river and lake edges, and on floodplains. The plant spreads by seeds and by underground stems known as rhizomes that send out new shoots above the ground and roots below. Stands of yellow iris develop thick mats of rhizomes that can connect several hundred plants. Fragments of rhizomes that break off can also form new plants.How to Identify- Flowers have three drooping, deep-yellow sepals with purple-brown markings that look like large petals, surrounding three smaller upright petals.- Yellow iris is the only iris in North America with entirely yellow flowers.- Flowers bloom between April and July at the top of stems 30 cm to 1 m (1 – 3 ft) tall that grow in groups of 2 to 10.- Leaves are flattened, 2 – 3 cm (0.8 – 1.2 in) wide and up to 1 m (3 ft) long, fanning out from the base.- Seeds are closely packed in rows within capsules 4 – 8 cm (1.6 – 3 in) long.When not flowering, yellow iris looks similar to the native blue flag iris (Iris versicolor). Blue flag iris is usually smaller, with leaves 10 to 80 cm long, stems 20 to 60 cm long, and purple-to-blue flowers. Yellow iris leaves may also be confused with other wetland plants, such as cattails (Typha spp.) and sweet flags (Acoraceae spp.).
