BuRO advice on the risks of Crassula helmsii in the Netherlands

Considering the risks of Crassula helmsii for biodiversity, ecosystem services and other social values in the Netherlands, BuRO advises the Ministry of Agriculture, Nature and Food Quality to take measures.

Advice BuRO

BuRO advises the Ministry of Agriculture, Nature and Food Quality to take or encourage measures to prevent new settlement and further spread of Australian swamp stonecrop. Examples of measures are:

  • Prevent of trade and release in nature.
  • Request the European Commission to include Crassula helmsii on the European Union list of invasive alien species of Union concern.
  • Promote awareness about the risks of the species.
  • Promote opportunities to prevent introduction into nature and further spread.
  • Promote early identification and rapid response to new isolated growth sites.
  • Promote the development of knowledge about effective methods of elimination, control (including ecosystem management) and prevention of further spread.
  • Promote a code of conduct for hygienic working among all parties that can help prevent further spread.


Australian swamp stonecrop (Crassula helmsii) is a perennial, evergreen swamp and aquatic plant that is not native to the Netherlands, but is originally from Australia and New Zealand. The plant is sold as an aquarium and pond plant.

Australian swamp stonecrop was first observed in the wild in the Netherlands in 1995 and the number of growing spots has been increasing since then, also in nature reserves. The plant competes with other plants. The effectiveness of elimination measures is low and so far elimination has only been successful for small contamination in isolated waters. The plant is considered invasive in several European countries.

These developments prompted the Office for Risk Assessment & Research (BuRO) of the Netherlands Food and Consumer Product Safety Authority (NVWA) to start an investigation into the risks of watercrassula.