The pest seaweed Undaria is a threat to Fiordland’s marine environment with its ability to quickly establish and outcompete native marine species.

Freshwater weeds degrade New Zealand's wetlands and waterways. The plants described here pose the most serious threats.

Golden dodder is a parasitic plant which sucks the nutrients out of host plants and weakens them. It's a threat to Waikato wetlands and lakes.

Hornwort is ranked New Zealand’s worst submerged weed, often smothering all other aquatic plant beds, including native and exotic.

Wilding conifers are invasive weeds that threaten to permanently alter the unique landscapes that are only found in New Zealand.