Last month I wrote a post on Irish species that were invasive in the United States, Irish Americans: invasive wildlife abroad. While writing that post I learnt that giant rhubarb, which is a native of Chile and Argentina, is one of Ireland’s most invasive plant species. Achill Island is heavily occupied by this invader. On a rainy day last week I decided to take a trip to my favourite childhood holiday destination to see how this alien species has changed Achill’s landscape.

Giant rhubarb or Gunnera tinctoria was introduced to Ireland as an ornamental garden plant and records show it was here as far back as 1939. It looks very similar to the rhubarb found in shops and in our vegetable gardens but it is not related to this plant. Giant rhubarb is an invasive species as it competes aggressively with native plants which can result in their decline. Ireland is not the only country affected by this South American species. It is also invasive in mainland Europe, North America, Australia and New Zealand.

One of the main success factors of giant rhubarb is that it can reproduce in two ways. Sexually by producing vast amount of seed and asexually by sending shoots through the ground. As a result, digging up plants or cutting them down will not kill them. Mayo County Council have produced a leaflet for landowners on how to deal with giant rhubarb. It recommends spraying herbicide on the leaves of fully grown plants.

Armed with this information, I had to take a look at Mayo’s most unwanted species. Mountain sheep were plentiful on my trip to Achill from North Mayo but I didn’t spot the alien invader. Once I crossed the bridge to the island, it was a very different picture. On the Atlantic Drive from Achill Sound to Keel, giant green leaves lined the ditches instead of the fuchsia I remembered. Abandoned cottages were even being invaded by this aggressive plant. I stopped the car to have a look over the ditches and instead of rushes, there were fields of giant rhubarb. It was as if the landowners had set up rhubarb farms.

Sadly, this invasive species is affecting Achill’s beauty. During my childhood holidays I loved Achill for the rugged landscape of its remote areas. The photo at the top of this post is from an isolated area on the south of the island. As you can see, giant rhubarb is everywhere. Having seen the devastation of this invasive species first hand and the extent it has spread across the island, I fear eradication measures may have started too late in the game. I hope that efforts of groups like Mayo County Council and the Botanical Gardens will prove me wrong. The beauty of the West (such as below) is dependent upon it!