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Curly Waterweed

Lagarosiphon major

Please keep in mind that it is illegal to uproot a plant without the landowner's consent and care should be taken at all times not to damage wild plants. Wild plants should never be picked for pleasure and some plants are protected by law.
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Plant Profile

Flowering Months:
Hydrocharitaceae (Naiad)
Life Cycle:
Maximum Size:
6 metres long
Ponds, water, wetland.

Pink, 3 petals
Pink flowers with thread-like stalks, held just above the surface of the water. 3 to 4mm in diameter.
A beaked seed capsule, about 3mm across. The average fruit contains approximately 9 seeds.
Linear, alternate, curly leaves which are very finely toothed. This is a freshwater, aquatic plant similar in appearance to other Waterweeds but this species has larger, curly-toothed leaves which spiral up the stems. Other British Waterweeds species have leaves which appear in whorls.
Other Names:
African Elodea, Curly Water Thyme, Giant Water Thyme, Giant Waterweed, Oxygen Weed, South African Oxygen Weed.
Frequency (UK):
Occasionally seen  

Similar Species

Other Information


Lagarosiphon major is a monocotic aquatic plant native to Southern Africa. Common names include African elodea, curly waterweed, oxygen weed and South African oxygen weed. It is a rhizomatous, perennial, submerged aquatic plant that inhabits freshwater water bodies with low to moderate nutrient concentrations. It is fast-growing and can totally fill the volume of a large shallow lake up to 3 meters deep, and can fill water control channels in New Zealand. It is dioecious, with adventitious roots and rhizomes that attach the plant to the substrate. Lagarosiphon major can reduce food and habitat for fish and other aquatic species, and can cause oxygen depletion in the water. It is considered an invasive species in many parts of the world, including New Zealand.


Curly Waterweed (Lagarosiphon major) is a fast-growing aquatic plant that is native to southern Africa and was introduced to other countries as an aquarium plant. It is a popular species for its ornamental leaves that resemble curly locks of hair and the beautiful underwater foliage.

This plant is a highly invasive species and is considered a threat to the local ecosystems in some regions. It has the ability to grow rapidly and outcompete other native aquatic plants, reducing the biodiversity of the area and disrupting the food chain. In some cases, it can even clog waterways and disrupt water flow, which can have an impact on the water quality, fishing and recreational activities.

Curly Waterweed can be spread through the release of plant fragments or through the movement of water-craft, which makes it a very effective invader. Once established, it is very difficult to remove, and the management of the plant can be expensive and time-consuming.

To prevent the spread of Curly Waterweed, it is important to take measures to prevent its release into the wild. This can be done by not releasing aquarium plants into the environment, and by not moving water-craft from one body of water to another without properly cleaning and drying it.

Curly Waterweed is a beautiful aquatic plant that has become a threat to the local ecosystems in some regions. It is important to be aware of its invasive nature and take measures to prevent its spread, to ensure the preservation of the biodiversity of our waterways and the health of our aquatic ecosystems.

In addition to its invasive nature, Curly Waterweed also has some other notable characteristics that make it an interesting plant.

One of the most notable features of this species is its growth rate. Curly Waterweed can grow up to 30cm per day, making it one of the fastest-growing aquatic plants. This rapid growth rate allows it to outcompete other species and dominate the underwater environment.

Another interesting characteristic of this plant is its photosynthetic activity. Curly Waterweed is capable of photosynthesizing both in light and dark conditions, making it a very adaptable species. This allows it to thrive in environments where other aquatic plants may struggle, such as in deep water where light penetration is limited.

Despite its invasive nature, Curly Waterweed has some beneficial properties as well. It is a valuable source of food and shelter for aquatic animals, and its growth can provide a habitat for fish and other aquatic life. In some regions, it is also used as a biological control for other aquatic weeds, such as the water hyacinth.

Curly Waterweed is a fascinating plant that has both positive and negative impacts on the environment. While it is important to prevent its spread and manage its invasive nature, it is also important to consider the benefits it can bring to the ecosystem and find ways to incorporate it in a sustainable manner.

Curly Waterweed is a multi-faceted species that can be both a blessing and a curse, depending on the context. It is important to understand its impacts on the environment and the measures that can be taken to manage it effectively.

One of the primary ways to manage the spread of Curly Waterweed is through physical removal methods. This can include hand-pulling, harvesting, and cutting, although these methods can be labor-intensive and are often only effective in small-scale situations.

Another method of management is the use of chemical control, such as herbicides. This approach can be effective in reducing the growth and spread of the plant, but it can also have negative impacts on other aquatic species and the surrounding environment.

There are also biological control methods that can be used to manage Curly Waterweed, such as the introduction of specific herbivores or pathogens that feed on the plant. This approach is often more sustainable and has fewer negative impacts, but it requires careful research and monitoring to ensure that the introduced species do not have unintended consequences.

In conclusion, the management of Curly Waterweed requires a multi-faceted approach that takes into consideration the specific context and the goals of the management plan. Physical removal, chemical control, and biological control are all methods that can be used, but it is important to carefully consider the pros and cons of each approach and choose the one that is most appropriate for the situation.

Distribution Map

Reproduced by kind permission of the BSBI.

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