Its big, itís bad, and itís banned. Chilean rhubarb, also known as giant rhubarb, is one Latin American youíre not going to want to tango with.
Chilean rhubarb (Gunnera tinctoria) is a giant, clump-forming herb with spiny stems. It has enormous umbrella-like leaves that grow up to 2m high, and although these die back in winter, their exotic appearance has appealed to landscapers and gardeners alike.
And so, the Chilean rhubarb wooed its way into many of our lives, and then began to wheedle its way into our natural environment. Its massive seed heads (spikes) that add to its tropical-meets-Jurassic Park looks, are actually a big part of the problem. These spikes produce oodles of fruit (up to 250 000 per plant) which are transported by birds and water to establish around coastal cliffs, wetlands, and along the banks of streams and rivers. Chilean rhubarb was first spotted growing wild in New Zealand in 1968, but its true nature has only been revealed over the last decade, and most spectacularly around Taranaki.
Imagine this; one year you have three clumps of Chilean rhubarb lending a tropical tone to your gardenÖand then the next year youíre suddenly battling through a spiky jungle and wondering when youíre going to come face to face with a tarantula. Well, itís been just about that bad around Mount Taranaki, and along parts of the Taranaki coastline Ė but rather than worrying about fantastical hairy spiders, Department of Conservation (DOC) staff and land-owners have been concerned with the fate of rare coastal herb species, a daytime flying moth unique to South Taranaki and North-West Nelson, and the geckos, skinks and seabirds that inhabit coastal areas. Chilean rhubarb is also a potential threat to culturally important plants such as harakeke (flax) and pingao; it can block drains and streams; and it can obstruct access to natural and recreational areas.
So for this Latino of the plant world, the best hope it has of getting our pulse rate up and our temperature rising is through indignation on behalf of our native flora and fauna. Chilean rhubarb is now nationally banned from sale, distribution and propagation, but in the past it has been grown throughout New Zealand. There are other species of giant Gunnera that look very similar to Chilean rhubarb and share the same characteristics, so plant with caution and watch out for any sudden appearances of giant Gunnera in the wild. If you see any suspicious looking plants, get in touch with your Regional Council or local DOC office.
For more information about invasive weeds, visit www.doc.govt.nz