Dog Strangling Vine

Under the Ontario Invasive Species Act, dog strangling vine is a restricted species, meaning it is illegal to import, deposit, release, breed/grow, buy, sell, lease or trade this DSV in Ontario.

Dog strangling vine (DSV) is a term used to refer to black swallowwort (Cynanchum louiseae) and pale swallowwort (Cynanchum rossicum). Both plants are considered invasive in Ontario. DSV is closely related members of the milkweed family from Europe and was brought over for ornamental purposes during the late 1800’s. DSV is known to invade grasslands, prairies, and forests.

Photo: John M. Randall, The Nature Conservancy, Bugwood.org

Photo: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

How to Identify

Structure

• Dog strangling vine’s rootstalk can grow from 60 cm – 2 m and is woody.
• The stem of this plant will wrap around trees, plants and other structures next to them.
  • This twining can also include other DSV vines forming a dense mat of stems and leaves.

Leaves

• Leaves are arranged oppositely on the stem of the plant.
• Leaves can range in colour from dark green to medium-light green and are hairless.
• The leaf margins can be smooth or slightly wavy.
• The leaves are oval to oblong at the base and pointed at the tip.

At different parts of the stem the morphology of the leaves will differ slightly. They start smaller and rounder at the base, at the mid part of the stem the leaves are largest, and at they become smaller and narrower towards the top.

Flowers

• Flowers are small, 5-9 mm long.
• Can be brownish red, maroon to pink, or dark purple in colour.
• Flowers resemble stars having 5 petals.
• Flowers come in clusters of 5-20.

Fruit/Seeds

• Pod-like fruits begin to grow in late July and August at the leaf axils.
• The seed pods resemble beans or small green peppers.
• Fruit is 4-7 cm long.
• Fruit is 0.5 cm wide.
• In the late summer these pods will open to release feathery white seeds.

Much like Common milkweed (Asclepias syriaca) the seeds are attached to feathery tuffs for long distance travel.

For more specific information regarding identification, please refer to Dog-strangling vine – Profile and Resources | Invasive Species Centre by the Invasive Species Centre.

Why the Concern?

Dog strangling vine creates dense patches that prevent light from reaching to the understory and aggressively smother plants that grow around it. This prevents the growth of native grassland and woodland plants, reducing biodiversity, and reducing the amount of suitable habitat for wildlife. The dense mats can also make recreational activities like walking and biking difficult as well as pets can get tangled in the vines.

The plant itself is very unappetizing for herbivores. This forces grazing animals to overgraze more palatable native species, removing more from the environment. This then allows for even more DSV to move in.

In agriculture, DSV has been observed to have moved into fields of soybeans and corn which can disrupt agricultural operations. Grazing livestock can have issues maneuvering through the dense mats and will avoid eating plants that have DSV.

The forestry industry is also impacted by DSV. Smaller saplings can be suppressed by the growth of the dense mats, impacting reforestation sites and plantations. Operational costs increase as removal efforts of DSV become increasingly necessary.

The Monarch Dilemma

Monarch butterflies often confuse DSV for native milkweeds (their host plants), as they are both in the milkweed family. As such, they lay their eggs on them, but it does not have what monarch caterpillars need to survive, resulting in starvation, posing a great risk to an already endangered species.

For more specific information regarding impacts, please refer to Dog-strangling vine – Profile and Resources | Invasive Species Centre by the Invasive Species Centre.

Control Measures

Management of dog strangling vine is difficult and early detection is essential. Depending on specific site conditions and time of year potential management options can include;

• Digging,
• Clipping,
• Mowing,
• Seed pod removal,
• Pulling and,
• Tarping.

For more specific information regarding best management practices, please refer to  Dog-strangling Vine (Vincetoxicum rossicum) Best Management Practices Technical Document for Land Managers by the Ontario Invasive Plant Council. 

Common buckthorn (Rhamnus cathartica) also known as European buckthorn, is medium to large sized shrub originating from Europe and western Asia. It was brought over in the 1800s for use as an ornamental shrub as well as for creating hedges as well as windbreaks in agricultural fields. It has since spread across Ontario thriving in mature forests, roadsides, riverbanks, hydro corridors and open fields.

Photo: Rob Routledge, Sault College, Bugwood.org

Photos: Chris Evans, University of Illinois, Bugwood.ca

How to Identify

Structure

• Medium to large sized shrub that usually grows 2-3 m tall and can sometimes grow up to 6 m.
• Stems of common buckthorn are around 25 cm in diameter.
• The plant will often grow taller and straighter in the shade, and shrubbier in the open.
• The stems can have straight thorns, but these are not always prominent.

Bark

• The bark is greyish-brown and prominent small lenticels can be observed on the bark.
• Younger bark is shiny and smooth and becomes rough and textured with maturity.
• The underlayer of the bark is yellow-green and the heartwood is orange in colour.

Leaves

• Leaves are smooth, round, and dark green, with a finely toothed edge.
• The leaves have pointed tips, and the leaves can be curved or folded.
• The leaves can grow opposite, sub-opposite and occasionally alternate to each other on the stem.

Flowers

• Flowers appear in early June.
• Flowers have 2-6 small yellow-green petals.
• The width of the flowers is generally 6 mm across.
• Flowers grow in dense clusters on threadlike stalks.

Fruits/Seeds

• Berries are small containing only 3-4 seeds.
• Fruit is black in colour when mature and remain on the plant into the winter.
• Narrow grooves can be observed on the back of the fruits.

For more specific information regarding identification, please refer to Invasive Common (European) Buckthorn (Rhamnus cathartica) Best Management Practices in Ontario by the Ontario Invasive Plant Council. 

Why the Concern?

Common buckthorn is known to spread into open and shaded environments, creating a dense thicket of branches. The species produces its leaves very early in spring before most native species providing them a competitive advantage.

It shades and suppresses grassland species and some woodland species, resulting in reduced native biodiversity in the area. Common buckthorn can also alter nitrogen levels in surrounding soils, leading to better conditions for itself and discouraging the growth of native species. It actively contributes to lower biodiversity in both forest and grassland environments.

Additionally, seeds can spread long distance through animal vectors as birds and other animals will eat the fruits and transport the seeds in their droppings. The fruit also has a laxative property to ensure that wildlife will spread the seeds widely.

In the agricultural industry common buckthorn is a concern as the plant can be a host for oat rust (Puccinia coronata f.sp. avenae), a fungal disease that can cause both leaf and crown rust in oats. The plant can also be an overwintering host for the soyabean aphid (Aphis glycines), an agricultural pest that can damage soybean crops. Both can cause overall yield losses for farmers.

For more specific information regarding impacts, please refer to Invasive Common (European) Buckthorn (Rhamnus cathartica) Best Management Practices in Ontario by the Ontario Invasive Plant Council. 

Control Measures

Management of common Buckthorn can vary depending on time of year and site conditions and therefore specific considerations need to be made when making management decisions. Some potential management options include;

• Pulling,
• Cutting/girdling,
• Flooding,
• Fire,
• Grazing,
• Mowing and,
• Herbicides.

For more specific information regarding best management practices, please refer to Invasive Common (European) Buckthorn (Rhamnus cathartica) Best Management Practices in Ontario by the Ontario Invasive Plant Council. 

Garlic mustard (Alliaria petiolata) is an edible herb native to Europe. The plant was originally introduced to North America in the early 1800s for its use as an edible herb, however it was then able to enter the wild and spread aggressively. The name comes from the fact that when the young leaves are crushed a strong aroma of garlic is released. This plant has been able to spread in both the continental United States and Canada through several states and provinces. Growing in a wide range of habitats, this species spreads quickly along roadsides, trails, and fence lines.

Photo: Richard Gardner, Bugwood.org

Photo: David Cappaert, Bugwood.org

Photo: Chris Evans, University of Illinois, Bugwood.org

How to Identify

Over the first two years of its life garlic mustard has two distinct life stages.

First Year Plants

Structure

• In the first year of growth garlic mustard grows low to the ground in a cluster of leaves.

Leaves

• Leaves are dark green in colour, kidney shaped and have scalloped edges.
• The leaves are clustered in a basal rosette.
• These leaves have a distinct garlic smell when crushed.

Roots

• The roots are slender and the taproot is white and “S” shaped.

Second Year Plants

Structure

• The plant can grow stems 0.3-1 m in height and these stems are hairy.

Leaves

• The leaves are alternate, triangular, and are coarsely toothed.
• Leaves grow from 3-8 cm long.
• Leaf shape can differ depending on their position on the stem.
  • Lower leaves are broader growing up to 10 cm across and are kidney shaped.
  • Upper leaves and are 5-10 cm across as they are triangular and narrow towards the tip.

Flowers

• Flowers are small and white with 4 petals.
• Appear in the spring when the stalk gets tall enough.

Fruit/Seeds

• Seed pods contain 10-20 small black seeds and
• The seed pods are 2.5-6 cm long.
• Seeds become viable after the whole plant dries out and dies for in midsummer.
• Seeds can last for several years in the soil.

For more specific information regarding identification, please refer to Garlic Mustard (Alliaria petiolata) Best Management Practices in Ontario by the Ontario Invasive Plant Council. 

Why the Concern?

Garlic mustard can become the dominant plant in a forest within 5 – 7 years. With no requirement for disturbance to become established it can be a threat to mature forests. With establishment native species like trilliums (Trillium sp.) can be out competed. While growing in the very early spring this plant has a direct negative effect on spring blooming flowers, smothering them in the large dense patches of garlic mustard.

Garlic mustard is an allelopathic species meaning the roots can produce chemicals in the soil that prevent the growth of other plant species. The chemicals can also affect beneficial fungi that assist plants and trees with the absorption of nutrients and water.

Additionally, the high nutrient content of the garlic mustard leaves results in faster decomposition of native leaf litter. This provides a competitive advantage for itself as it can establish in low leaf litter environments while many other native species do not have this ability.

For more specific information regarding impacts, please refer to Garlic Mustard (Alliaria petiolata) Best Management Practices in Ontario by the Ontario Invasive Plant Council. 

Control Measures

For the management of Garlic mustard it is recommended that more than one management strategy be used in an integrated pest management approach. Multiple methods help to ensure the success of the overall removal efforts. Specific management decisions also depend on site and plant conditions, as well as time of year. Potential management options include;

• Hand pulling,
• Clipping flower heads,
• Mowing/cutting,
• Over-planting,
• Herbicide application,
• Biological controls, and
• Controlled Burns.

For more specific information regarding best management practices, please refer to Garlic Mustard (Alliaria petiolata) Best Management Practices in Ontario by the Ontario Invasive Plant Council. 

Under the Ontario Invasive Species Act, invasive phragmites is a restricted species, meaning it is illegal to import, deposit, release, breed/grow, buy, sell, lease or trade invasive phragmites in Ontario.

Phragmites also known as common reed (Phragmites australis subsp. australis) is an invasive wetland grass that is known for significantly altering wetland environments, due to its large size and aggressive growth. Rivers, creeks, ponds, roadside ditches and wetlands are especially susceptible to phragmites. Invasive Phragmites was likely first introduced into North America in the early 1800s. Although the exact method of spread is not known, there are theories that it was introduced intentionally in the horticultural trade and accidentally in ballast water of ships.

There is also a native species of phragmites, that does not grow as tall, dense, or as aggressive, and has noticeable red stems.

Photos: Caleb Slemmons, National Ecological Observatory Network, Bugwood.org

How to Identify

Stems

• Invasive phragmites stems can grow up to 5 m in height
• The stems grow in very dense monoculture stands (up to 200 stems per m²).
• Both living and dead stems are found in the stands leading to increased density.
• The stems can be around 0.5-1.5 cm in diameter
• The stems are usually characterized by their tan or beige colouration however overall stem colour changes depending on season.
  • During the spring the stems are mostly green.
  • In the summer and fall months the stems begin to turn into a pale-yellow colour.
  • In the winter all the stems in the stand turn to a tan or beige colour.

Rhizomes

The rhizomes are belowground structures that allow the plant to spread below the surface and can produce new shoots.

• A rhizome can grow up to 10 ft in a single season under optimal conditions.
• Rhizomes grow 1-3 ft below the surface of the soil.
• These rhizomes account for more than 80% of the plant’s biomass.

Stolons

Stolons are an aboveground growth structure of phragmites that grow horizontally along the surface. The stolons will produce new stems and roots at the nodes, aiding in outward spread.

• The stolons are red and tan in colour.
• Produce several new stands per stolon at nodules.

Leaves

• Leaves are blue green in colour, alternate on the stems, and flat tapering to a point.
• A leaf can be up to 70 cm long.
• Often the leaves are at a 45-degree angle from the plant.
• The ligule is thin (<1 mm wide), slightly translucent and has hairs up to 1.5 mm long.

Seeds

• Seedheads are large and very dense.
• The colour differs depending on the time of year.
  • In the early stages of seed head growth, they are a purple – brown colour.
  • Then as the plant matures the seed heads become white – tan and have a fluffier appearance.

For more specific information regarding identification, please refer to Invasive Phragmites (Phragmites australis) Best Management Practices in Ontario by the Ontario Invasive Plant Council.  

Why the Concern?

Invasive phragmites spreads very easily, through both human caused and natural pathways. The seeds can travel through the wind and water spreading far distances. However, its main method of spread is its horizontal growth structures, rhizomes and stolons. The rhizomes are particularly hard to manage as they are underground and account for a large percentage of the plant’s biomass. These rhizomes can also brake off during storms and travel to create new stands in other places.

The dense stands can prevent light from reaching the surface, preventing the growth of many native wetland plants, and reducing biodiversity. This density can also hinder the movement of wildlife as well as reduce suitable habitat.

Significant plant material can build up on the water’s surface and the bottom beds. This hinders the mobility of some fish species, which lowers species diversity. This can also result in negative effects to both the recreational and industrial fishing industries, as well as other recreational activities like swimming and boating.

The agricultural industry is also impacted as phragmites stands growing near agricultural fields can change the water and nutrient regimes impacting crop yields. Phragmites can clog agricultural drainage systems which causes slower field drying and increased floods leading to yield losses from delayed or repeated planting.

Phragmites also poses risks to humans as phragmites can also impact driving site lines due to its high density on roadsides and which causes hazards while driving especially around corners. Also, there is increased fire risk is associated with stands of phragmites as stands are usually composed of a lot of dead stalks which are highly combustible.

For more information regarding impacts, please refer to Invasive Phragmites (Phragmites australis) Best Management Practices in Ontario by the Ontario Invasive Plant Council.  

Control Measures

Management of invasive phragmites can differ greatly depending on patch size, time of year, and the presence of standing water. Phragmites management also often requires the use of multiple management methods to ensure long-term success. Potential management options for invasive phragmites include;

• Herbicide application,
• Cutting/spading,
• Mulching,
• Flooding and,
• Prescribed burns.

For more specific information regarding best management practices, please refer to Invasive Phragmites (Phragmites australis) Best Management Practices in Ontario by the Ontario Invasive Plant Council. 

Wild parsnip (Pastinaca sativa) is a tall invasive plant apart of the carrot/parsley family. Other common names for this species include hart’s eye, poison parsnip, bird’s nest, and common parsnip. Wild parsnip can often be found in open places such as fields, ditches, and disturbed areas. Caution should be taken when around wild parsnip as the plant’s sap contains toxic compounds, called furanocoumarins. These compounds can cause photodermatitis, which results in painful blisters and rashes when exposed to the sun. If you touch parsnip, keep the area out of direct sun and wash with soap within 10 mins for the best chance of removal. Avoid exposing your skin to sunlight for at least 48 hours if you think you might have got it on you.

Photos: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Photo: Ohio State Weed Lab, The Ohio State University, Bugwood.org

Photo: Theodore Webster, USDA Agricultural Research Service, Bugwood.org

How to Identify

Stems

• The stems can range from 30 cm – 1.5 m in height depending on the site conditions.
• The stems are circular and hollow, and not often with many hairs.

Leaves

• The leaves of wild parsnip grow alternately up the stem.
• The leaves are around 15 cm in length, with large, jagged edges.
• Leaves are made up of leaflets that grow oppositely from each other up the leaf stem (petiole).

Flowers

• Each flower has 5 petals and grows in clusters with other flowers.
• These clusters are very noticeable, with a large flat, yellow, umbrella shaped structure that can be 5-15 cm across.

Seeds

• After the flowers bloom a dry fruit or seed is produced.
• The fruit are initially oval shaped and 6 mm long then with maturity the fruit split into two.
• These two sections are smooth, round, flat, 5 – 7 mm long, and each section contains 1 seed.
• Seeds can remain on the stem for a while often dispersing between August and November.
• Wild parsnip seeds can remain viable for up to 5 years in soil.

For more specific information regarding identification, please refer to Wild Parsnip (Pastinaca sativa) Best Management Practices in Ontario by the Ontario Invasive Plant Council.  

Why the Concern?

It can take over large areas of land and quickly become a dominant species. It can persist easily in fields and disturbed areas. When the density increases, it can have a negative effect on lower growing plants, as they are easily shaded out.

In agriculture it is a concern especially in fields where producers have decided to use reduced tillage or no-till systems, less mixing of the soil, as wild parsnip can take over easier.

These plants are not very pollinator friendly as it displaces species which are more pollinator friendly and species like honeybees do not visit it.

The plant is dangerous to for humans to touch as it contains toxic compounds, furanocoumarins. These compounds are found in the sap and can cause serious rashes, blisters and burns, when the sap is touched and exposed to sunlight.

For more specific information regarding impacts, please refer to Wild Parsnip (Pastinaca sativa) Best Management Practices in Ontario by the Ontario Invasive Plant Council.  

Control Measures

If attempting any management efforts, it is very important to utilize protective clothing and PPE due to the toxic compounds found in the plant. Types of PPE can include eye protection, long-sleeved shirts, pants, and water-proof gloves. Additional and recommended protection would be provided by a disposable spray suit over clothing. After working around the plant, it is important to carefully remove PPE and wash both yourself and your clothes with soap and water immediately. Also clean any equipment used in management efforts.

If exposed to any wild parsnip sap was thoroughly with soap and water, avoid exposing the area to any further sunlight/UV, seek medical attention if symptoms of photodermatitis appear. Additionally, if there is any chance your eyes were exposed to the sap immediately flush the eye with water and seek immediate medical attention.

Wild parsnip management should only be done with an abundance of caution to ensure that the sap is not transferred onto to people. The goal of management efforts should be to reduce and or prevent the development of seed production as that is the only way the plant reproduces. Management options for wild parsnip include;

• Mowing,
• Pulling (with a shovel),
• Tarping,
• Tillage,
• Herbicide application and,
• .   Burning.

For more specific information regarding best management practices, please refer to Wild Parsnip (Pastinaca sativa) Best Management Practices in Ontario by the Ontario Invasive Plant Council

Under the Ontario Invasive Species Act, water soldier is a prohibited species, meaning it is illegal to import, possess, deposit, release, transport, breed/grow, buy, sell, lease or trade water soldier in Ontario.

Water soldier (Stratiotes aloides) is an invasive perennial aquatic plant native to Europe and northwest Asia. It was sold for use as an ornamental plant in Ontario for water gardens, which is the most likely source of its introduction. It often begins as a submergent plant growing along the substrate of the water. As the summer progresses the plants become buoyant and later begin to sink again when the leaves are waterlogged. They can grow in large patches that hinder other native aquatic plants, boaters and swimmers. Once the plant matures it can reproduce through offshoots, turions and clonal fragmentation   that ultimately become new plants. One plant can offshoot several times leading to fast spread.

Photos: Rob Wilson, Lake Simcoe Region Conservation Authority, Bugwood.org

How to Identify

Water soldier can often be found in dense patches in the water either on the bottom or floating on the surface.

Leaves

• Water soldier grows in a rosette or a group of leaves circled around the center of the plant.
• Each leaf can grow to around 40 cm long, are shaped like swords, bright green, and have edges that are highly serrated.
• The serrated edges of the leaves is one of the features that differentiates it from lookalike species as this trait is unique among similar species.

Roots

• Roots may or may not be rooted into the substrate.
• The root systems are not dense.

Seeds/Flower/Fruits

• Water soldier’s flowers appear as white 3 petaled flowers that turn into berry-like fruits.
• These fruits contain 24 seeds each.
• Water soldier flowering is rare in Ontario plants.

For more specific information regarding identification, please refer to Aquatic Invasive Plants – Best Management Practices in Ontario  by the Ontario Invasive Plant Council.    

Why the Concern?

Water soldier can become a monoculture taking over large areas, preventing other aquatic species from establishing. The dense growth leads to heavy competition with native plants for necessities resulting in lower biodiversity and reduced habitat quality for plants and wildlife.

With dense mats of floating vegetation problems arise, such as making it difficult and potentially dangerous to participate in recreational activities such as swimming and boating. The sharp serrated edges of the leaves can cut up people who try and handle it or swim through it. As a result, special care needs to be taken near this plant.

For more specific information regarding impacts, please refer to Aquatic Invasive Plants – Best Management Practices in Ontario  by the Ontario Invasive Plant Council.    

Control Measures

Water soldier management should be tailored specifically to the site conditions and with the use of multiple management approaches into an integrative management approach. Management options can include;

• Hand removal,
• Mechanical harvesting,
• Herbicide applications and,
• Raking.

For more specific information regarding best management practices, please refer to Aquatic Invasive Plants – Best Management Practices in Ontario  by the Ontario Invasive Plant Council.    

Under the Ontario Invasive Species Act, Japanese knotweed is a restricted species, meaning it is illegal to import, deposit, release, breed/grow, buy, sell, lease or trade Japanese knotweed in Ontario.

Japanese knotweed (Fallopia japonica) is an invasive perennial herbaceous plant that is native to eastern Asia. The plant has several common names such as Mexican bamboo, huzhang, Japanese polygonum, and fleeceflower. The scientific names Polygonum cuspidatum and Reynoutria japonica are also used in literature for the species. The species was introduced as a horticultural plant in North America in the late 19^th century. It was intended to be used as a plant for livestock forage, erosion control, and as an ornamental.

Photo: Bradley Kriekhaus, USDA Forest Service, Bugwood.org

Photo: Milan Zubrik, Forest Research Institute – Slovakia, Bugwood.org

How to Identify

Stems

• The stems are hollow, smooth and jointed.
• The stems of wild parsnip are purple to green in colour.
• The nodes on the stem are Reddish-brown and solid.
• The stems can grow between 1-3 m in height when mature and up to 2.5 cm in diameter.

In the fall the stems will begin to die back and then the dead stalks will remain over winter.

Leaves

• The leaves are alternately arranged on the stem.
• The shape of the leaves is oval to triangle in shape with a pointed tip and flat base.
• The stalk of the leaf (petiole) is long.
• Leaves are 7-10 cm wide and can be 10-17cm long.

Rhizomes

• The exterior of the rhizomes is dark brown, while the interior structure of the rhizome is bright orange.
• The rhizome can grow to be around 14-18 m in length.
• The rhizomes can sit in the soil greater than 2 m deep.
• Rhizomes can spread up to 50 cm/year.

A piece of the rhizomes as small as 1 cm can produce a new plant. The rhizomes make up two thirds of the plant’s total biomass.

Flowers

• Flowers are small, white – green and produced in clusters (branching panicles).
• Clusters can be longer than the leaves nearest to them.

Fruit/Seeds

• The fruits and seeds are very small, winged, triangular, and shiny

Winged shape assists with dispersal through the wind or water.

For more specific information regarding identification, please refer to Japanese knotweed (Reynoutria japonica) Best Management Practices in Ontario by the Ontario Invasive Plant Council.

Why the Concern?

Japanese knotweed can grow in thick mats blocking out the sunlight for plants underneath them. In the fall and spring new plant growth can struggle to grow against the thick mats of decaying Japanese knotweed. This thick growth can also damage infrastructure and block access to water, limiting recreational activities.

These stands also do not support as many wildlife species as native alternatives leading to decreased species diversity.

Increased erosion is found in areas with these plants as their root systems are not as dense as those found in native plants.

For more specific information regarding impacts, please refer to Japanese knotweed (Reynoutria japonica) Best Management Practices in Ontario by the Ontario Invasive Plant Council.

Control Measures

The management of Japanese knotweed can take multiple years to ensure the plant will not regenerate in the afflicted area. Depending on specific site conditions and time of year potential management options can include;

• Mowing/Cutting,
• Digging,
• Excavation,
• Grazing,
• Tarping and,
• Herbicide Applications

For more specific information regarding best management practices, please refer to Japanese knotweed (Reynoutria japonica) Best Management Practices in Ontario by the Ontario Invasive Plant Council.