New Zealand Pigmyweed

Small green weed with leaves (4mm – 2cm long) arranged opposite each other on rigid, round, fleshy stems.

New Zealand pigmyweed (Crassula helmsii), AKA Australian Swamp Stonecrop, can grow in three forms: on land, emergent (coming out of the water) and submerged (permanently under water).

The leaves have a sharp tip. Flowers with 4 white petals appear between Jul – Sep.

New Zealand pigmyweed is a hardy plant that causes major problems in nature reserves and recreation areas by forming 100% cover and smothering and out-competing native flora for nutrients.

It spreads mainly by tiny plant fragments being transferred into new locations, which can then grow into a new plant. These fragments can be easily moved from place to place by boats, uncleaned equipment, or water-birds.

All aquatic weeds present the following threats:

They form thick, dense mats that prevent light from reaching native plants and can be mistaken for solid ground by children and animals.

The thick mats also prevent oxygen from entering the water, drastically reducing oxygen levels, which may kill fish and other aquatic life.

A large infestation greatly reduces access for recreational water activities.

Mats of aquatic weeds often result in a bad smell and reduced visibility in the water.

Dense mats can reduce the flow of water and increase the risk of flooding.

Check, clean and disinfect all equipment, boots, wheels and anything that made contact with the water. This will ensure you don’t carry fragments to other possible habitats.

The control of large infestations of aquatic weeds will require the services of an appropriately certified invasive species control company.

If you encounter New Zealand pigmyweed please enter the details into our log.