Crassula helmsii (also know as New Zealand pigmyweed) is a non-native invasive plant oringinally found in Australia and New Zealand. It's an aquatic species of succulent which, in 2014 along with 4 other plants was banned from sale in the UK!
Crassula helmsii is a highly adaptable plant which can tolerate many different growing conditions. It can grow below the water's surface or at the edges or margins of water. It's even semiterrestrial meaning it can also grow on land if the ground is damp enough.
The species is one of the biggest threats to Wetlands in the UK and if left untreated it can completely cover the surface of the pond. Once established, it can outcompete native plants forming a dense mat covering which shades out other plants.
It can also cause issues for our wildlife. If left to it's own devices, it can even cover exposed mud, which is a vital habitat for wading birds.
We have this on our reserve at Washington Wetland Centre
We have an ongoing management plan that targets this species, as well as a variety of others.
We monitor all of our reserve areas for crassula throughout the year, making sure it does not get the chance to spread and take over our wetlands. This is done in a variety of ways:
Crassula can grow from a tiny fragment that has been left untreated. It can be transferred to boots and wellies so if people have been walking around infected areas it can move it from place to place. Biosecurity of footwear is really important and we are very careful to thouroughly wash our footwear when working with this invasive species.
There are things you can do at home to reduce the impacts of non-native plant species - read more