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Purple Loosestrife

Lythrum salicaria

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Plant Profile

Flowering Months:
Lythraceae (Purple Loosestrife)
Life Cycle:
Maximum Size:
150 centimetres tall
Bogs, ditches, fens, fields, marshes, meadows, ponds, riverbanks, riversides, swamps, waterside, wetland, woodland.

Purple, 6 petals
Bright purple flower spikes in whorls up the stem, 6 petals.
The fruit capsules are enclosed within the sepals and consist of many reddish tiny seeds.
The leaves can be either opposite or in whorls of 3, and are sometimes slightly hairy. They are stalkless, long and slender, and are either heart-shaped or rounded at the base of their leaves.
Other Names:
Purple Lythrum, Rainbow Weed, Salicaria, Spiked Loosestrife, Swamp Loosestrife.
Frequency (UK):

Other Information


Lythrum salicaria, also known as purple loosestrife, is a herbaceous perennial plant that is native to Europe and Asia. It is known for its spikes of bright purple flowers that bloom in the summer, and its leaves which are opposite and lance-shaped. It prefers wet soil and is often found in wetland areas such as marshes, swamps, and along the edges of streams and ponds. It is also considered an invasive species in many areas of North America and Europe, as it can outcompete native plants and reduce biodiversity in wetlands. It was brought to North America as a ornamental plant and was intentionally or accidentally released into the wild.


Purple Loosestrife, scientifically known as Lythrum salicaria, is a tall, herbaceous plant that is native to Europe and Asia. It is a striking plant with its spiky purple flowers that bloom during the summer months. Despite its beauty, Purple Loosestrife is considered an invasive species in many parts of the world, including North America.

Purple Loosestrife was introduced to North America in the early 19th century as an ornamental plant. It was often planted in gardens and along roadsides for its beauty. However, over time, it has escaped cultivation and has become a widespread problem. Purple Loosestrife grows quickly and can outcompete native plants for resources such as sunlight, water, and nutrients. This can lead to a decrease in biodiversity and can even alter the structure and function of ecosystems.

One of the reasons why Purple Loosestrife is such a successful invader is because it can reproduce both sexually and asexually. It produces large numbers of seeds that are dispersed by wind and water. It can also spread vegetatively through its root system. This means that a single plant can quickly give rise to a large patch, making it difficult to control.

The impact of Purple Loosestrife on ecosystems can be significant. It can form dense stands that can alter the hydrology of wetlands, making them less suitable for certain species. It can also reduce the abundance of native plants that provide food and habitat for wildlife. In addition, Purple Loosestrife is not a good food source for many native insects, which can have ripple effects throughout the food web.

Efforts to control the spread of Purple Loosestrife include a combination of mechanical, chemical, and biological methods. Mechanical methods involve physically removing the plants, while chemical methods involve using herbicides to kill them. Biological control involves introducing natural enemies of the plant, such as insects or pathogens, to help control its spread. However, care must be taken to ensure that these methods do not harm native species.

Despite its invasive nature, Purple Loosestrife does have some uses. It has been used in traditional medicine for centuries and has been studied for its potential medicinal properties. It is also used in some parts of the world as a source of dye for textiles.

Purple Loosestrife is a hardy plant that can tolerate a wide range of environmental conditions. It can grow in both wet and dry soils and can even survive in areas with high levels of salt. This adaptability has made it a successful invader in many parts of the world.

The plant has also been the subject of controversy, particularly in North America. Some people argue that it is not as harmful as it is often portrayed and that it can even provide important ecological benefits, such as reducing soil erosion and providing food and habitat for certain wildlife species. However, these claims have been disputed by many scientists who have studied the plant's impacts on ecosystems.

There have been some successful efforts to control the spread of Purple Loosestrife in certain areas. For example, in the United States, the plant has been listed as a noxious weed in several states, and efforts to eradicate it have been ongoing for many years. In Canada, the plant is considered a nuisance and efforts to control its spread are also underway.

Despite the challenges posed by Purple Loosestrife, there is hope for restoring ecosystems affected by its invasion. In some areas, efforts are underway to restore wetlands and other habitats by removing the plant and replanting with native species. These restoration projects can help improve biodiversity and provide important habitat for wildlife.

In addition to its impacts on ecosystems, Purple Loosestrife can also have economic impacts. It can clog irrigation systems, reduce the quality of grazing land for livestock, and reduce the aesthetic value of natural areas. This can have significant economic costs for farmers, ranchers, and tourism industries.

There are also cultural and historical connections to Purple Loosestrife. In some parts of Europe, the plant has been used in traditional medicine for centuries to treat a variety of ailments. In North America, it has become a popular subject for artists and photographers who are drawn to its striking purple blooms.

However, the ecological impacts of Purple Loosestrife cannot be ignored. Its ability to outcompete native species and alter ecosystem structure and function make it a serious threat to biodiversity. As such, it is important for individuals and communities to be aware of the risks posed by invasive species and to take steps to prevent their introduction and spread.

Preventing the spread of invasive species like Purple Loosestrife requires a concerted effort from all sectors of society. This includes individuals, businesses, and government agencies working together to prevent the introduction of new invasive species and to control the spread of existing ones. It also requires public education and outreach to raise awareness about the risks posed by invasive species and the steps that can be taken to prevent their spread.

It is important to note that not all non-native plants are invasive. Many non-native plants have been introduced to new areas intentionally and have been successfully integrated into their new ecosystems without causing harm. However, some non-native species, like Purple Loosestrife, can become invasive if they are introduced to a new area where they have no natural predators or competitors.

Preventing the introduction and spread of invasive species can be challenging, but there are several steps that individuals and communities can take to reduce the risk. One important step is to avoid planting non-native species that are known to be invasive. It is also important to properly dispose of yard waste and to avoid transporting soil or plant materials from one area to another.

When hiking or camping in natural areas, it is important to be aware of the risks posed by invasive species and to take steps to prevent their spread. This includes cleaning hiking boots, camping gear, and other equipment to remove any seeds or plant materials that may be attached.

One challenge in controlling the spread of Purple Loosestrife and other invasive species is the fact that they often spread rapidly and can be difficult to control once established. In some cases, herbicides or other chemical treatments may be necessary to control their growth. However, these methods can have negative impacts on other plant and animal species in the affected area, and there is a risk of unintended consequences.

As a result, there is growing interest in developing non-chemical methods for controlling invasive species. One promising approach is biological control, which involves introducing natural enemies of the invasive species, such as insects or pathogens, to control their growth. Biological control has been used successfully in some cases, but it is important to carefully evaluate the potential risks and benefits of any proposed control method before implementation.

Another important approach to controlling invasive species is to focus on preventing their introduction in the first place. This can be accomplished through measures such as screening and testing of imported plant materials, increased public education and outreach, and stricter regulations on the import and transport of potentially invasive species.

In addition to these efforts, it is also important to continue monitoring and researching the impacts of invasive species on ecosystems. This can help us better understand their behavior and develop more effective strategies for controlling their growth and restoring affected ecosystems.

In conclusion, Purple Loosestrife is a beautiful but invasive plant that poses significant threats to ecosystems and human activities. Preventing the spread of invasive species like Purple Loosestrife requires a collective effort from all of us, including individuals, businesses, and government agencies. By working together and using a variety of approaches, we can protect our natural world and ensure that future generations can enjoy the beauty and diversity of our planet's ecosystems.


Video 1: Purple Loosestrife filmed at Worthington Lakes, Lancashire on the 12th July 2022.


Video 2: Purple Loosestrife filmed at Lower Moor Farm Nature Reserve in Wiltshire on the 28th June 2023.


Music credits
Isolated by Kevin MacLeod is licensed under a Creative Commons Attribution 4.0 license.

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