The water hyacinth, a floating aquatic plant originally from South America, has become a major ecological problem in France's waterways. Introduced in the 19th century, it was initially admired for its attractive blue flowers and was planted in gardens and ponds. Over time, it escaped cultivation and spread rapidly across the country, from the south near Montpellier to regions like Brittany and even into the north and east. The plant's ability to reproduce from just a small fragment makes it extremely hard to control—each piece can grow into a full plant, and under ideal conditions, its mass can double every two weeks. Today, the water hyacinth forms thick mats on the surface of water bodies, sometimes up to three meters deep. These dense carpets block sunlight from reaching underwater plants and reduce oxygen levels in the water, which can suffocate fish and other aquatic life. The plant's spread has been made worse by climate change, which has led to milder winters. This has allowed the water hyacinth to thrive in areas where it previously could not survive, especially in the south since the 1970s and in northern regions from the 1990s onward. In an effort to combat the problem, the French government banned the sale, purchase, and possession of the water hyacinth in 2018. This was done to prevent further spread and to encourage the removal of existing plants. However, eliminating the plant entirely remains a challenge. Mechanical methods, such as using barges with cranes to pull the plants from the water, are employed, but the amount of plant material removed is enormous and often waterlogged, making it difficult to transport and process. Despite these efforts, the water hyacinth continues to disrupt the natural balance of French rivers and wetlands. Its persistence highlights the difficulty of managing invasive species, especially when environmental changes like climate change create conditions that favor their spread. Scientists and environmental agencies are still working to find more effective and sustainable ways to manage this ecological threat.