What does it look like?
Chilean rhubarb is a giant, rhubarb-like herb with huge prickly leaves that can reach up to 2.5m tall. In winter, it dies back to large creeping stems and large, sausage-like flower spikes that are up to 1m tall. The spikes are covered in little flowers that are followed by tiny orange fruits.
In New Zealand, Chilean rhubarb mainly occupies damp sites on wetland and riparian margins, coastal cliffs, moist banks and disturbed sites. It often grows in light shade. It is scattered throughout New Zealand but is most common in high rainfall areas, such as South Taranaki and Westland.
Chilean rhubarb is present in Northland, both in gardens and in the wild. In the east there is the occasional plant that has "escaped" into the wild but in the west, in the high rainfall area around Waimamaku, it is present in small amounts in pastures, wetlands, riverbanks and even forests.
Why is it a problem?
Chilean rhubarb is extremely tolerant of salt, a wide variety of soil conditions, and very wet swampy sites and seasonally wet ground. It produces abundant fruit, which are dispersed by birds, and forms dense patches that exclude virtually all other plants.
Chilean rhubarb produces large amounts of viable seed. There is no information about seed longevity. Once established, infestations can increase in size from the massive, spreading roots and it also grows readily from any stem fragments which break off the plants.
The seeds of Chilean rhubarb are spread by birds and water. Seeds and rhizomes (roots) are also spread deliberately by humans (for ornamental purposes and inadvertently in garden waste and soil. Stem fragments can break off plants and tumble down steep slopes or be transported by water.