Water hyacinth

Eichhornia crassipes


  • The water hyacinth is a free-floating aquatic plant native to the Amazon basin. It was imported into Europe as an ornamental plant with attractive flowers and it became popular in horticulture, from where it easily spread into the environment.
  • The species has since invaded river basins in France, Italy, Portugal and Spain.
  • The plant grows extremely fast and develops into thick floating mats which, if uncontrolled, can cover entire water bodies. These mats block out the light and deplete the water of oxygen, smothering out all other native plants and animals. It also hinders water circulation, clogs up navigation routes, and causes immense damage to agriculture through increased water loss.
  • EU-level action includes a ban on sales and planting or keeping the plant, including in isolated ponds.
  • Early detection and eradication: given the costs of management, a prompt response to newly establishing populations will be important to avoid later management costs.
  • Identification information: - aquatic floating plant - leaves have distinctive swollen bases - leaves are glossy, thick and rounded - flowers, rarely present in UK, are pale purple and clustered in spike reminiscent of a hya-cinth
  • Biodiversity or related ecosystem services: the plant grows in thick floating mats reducing light and leading to oxygen depletion, thus seriously disturbing aquatic ecosystems, causing loss of species and habitats. It is considered as the most damaging aquatic weed in the world.
  • Human health: infestations can intensify mosquito problems.
  • Economy: it has serious impacts on agriculture due to increased water loss due to evapotranspiration. It can also suppress crops and inhibits germination. The plant also disturbs drainage, it damages hydropower plants, hampers recreation and disrupts fisheries.

Images courtesy of Q Bank and GBNNSS

Invasive Species Ireland

Invasive Species Ireland