John & Maria's Garden Pages

The invasiveness of Gunnera

Every exotic or larger scale water gardener loves the massive leaves and structure of the Brazilian perennial sold as Gunnera manicata.  Hardly surprising, as a clump by the waterside, or in a wet area of a garden, adds a true tropical touch to any planting.

Now it appears we've all been getting it wrong.  According to recent research by the Royal Horticultural Society what's been widely sold as G.manicata is in fact a hybrid between G.manicata and the invasive G.tinctoria, banned fom sale or cultivation in the UK since 2017.  This hybrid, G. x cryptica, has now been found to be equally invasive and will now also be banned from sale and new cultivation.

The research that led to the desicion can be found here, in the journal Sibbaldia.

What this means for gardeners is yet to be seen.  After all, clumps of Gunnera are everywhere.  Will we now be forever denied the sight of sunlight spearing through the massive leaves?

Will some of the great Cornish gardens lose their jungle plantings of the aptly named giant rhubarb? Or will gardeners be allowed to control any invasion risk by removing the massive flower heads before they set and then shed seed to float downstream?

Time will tell, but, if we lose this plant our gardens will be the poorer for it.

It doesn't affect me personally - I simply don't have the room for another plant this size.  But it does affect The Garden House, with a large clump by the arboretum lake, a lake that is fed by and returns into a local Dartmoor stream that eventually feeds the Tamar.  Will we have to remove it?  I don't know - but I'll find out.  I'd miss this view: