Day of the Triffids: Giant rhubarb plants nicknamed ‘dinosaur food’ because of its size will be BANNED after scientists realise it’s an invasive hybrid similar to Japanese knotweed
- Gardeners who already have giant rhubarb need to be careful that it doesn’t escape.
- The plant will be banned from sale in the UK after research found it poses a risk to native plants.
Giant rhubarb, with its spiny leaves stretching up to nine feet, has long been a favorite in stately homes and large gardens.
However, it will now be banned from sale in the UK after research showed it poses a risk to native plants.
Experts say the South American species, nicknamed “dinosaur food” because of its colossal size, is considered a “plant of concern” along with Japanese knotweed.
Gardeners who already have giant rhubarb in their flowerbeds must ensure that it does not escape and cannot be replanted or regrown.
The giant rhubarb commonly grown in Britain was thought to be a species called Gunnera manicata, which has not become widespread. A species called Gunnera tinctoria is already banned.
Giant rhubarb will be banned from sale in the UK after research showed it poses a risk to native plants.
Experts say the South American species, nicknamed “dinosaur food” because of its colossal size, is considered a “plant of concern” along with Japanese knotweed.
Gardeners who already have giant rhubarb in their flowerbeds must ensure that it does not escape.
But researchers from the Royal Horticultural Society have discovered that almost all giant rhubarb in the UK is a hybrid variety, Gunnera x cryptica, created by crossing Manicata and Tinctoria.
The hybrid can be very invasive. In parts of Cornwall, Devon, Scotland and Ireland it smothers other plants on moors, heaths and along waterways.
When it grows on soft coastal rocks, it can cause erosion because its heavy weight causes the rock to crumble, taking soil and rocks with it.
It spreads through seeds and rhizomes, root-like growths that spread just below the soil’s surface in search of new areas to colonize. Their roots grow about three feet deep.
The Department for Environment, Food and Rural Affairs recommends that it be treated as a prohibited species, so the RHS is changing its advice to gardeners. The society’s research was published in the journal Sibbaldia.
John David, head of horticultural taxonomy at the RHS, told the Guardian: “It was surprising to discover that a plant that had been a favorite in our gardens because of its impressive size and exotic appearance was an overlooked hybrid. ‘