Retailers who sell pond plants are being advised to stop selling plants named as Gunnera manicata because of the likelihood that many plants under that name are the result of crossing with G.tinctoria, which is banned from sale.

Under the Invasive Alien Species (Enforcement and Permitting) Order 2019 G. tinctoria cannot be sold. A recent research paper published by the Royal Horticultural Society asserts that all G.manicata in trade is either the cross between G.manicata and G.tinctoria, or misidentified G. tinctoria. Defra has confirmed that these hybrid plants should therefore not be sold. OATA’s advice also therefore covers Gunnera × cryptica which is the name of the hybrid plant.

“Our advice to retailers is to not stock or sell any giant Gunnera species because, unless their suppliers can prove provenance, it may be a hybrid species,” said OATA Chief Executive Dominic Whitmee.

“Defra has informed us that the cross of G. manicata and G. tinctoria is banned from sale because hybrids of a parent that is banned, in this case G. tinctoria, are also banned under the Invasive Alien Species (Enforcement and Permitting) Order 2019. Although legally, G. manicata can still be sold, we advise it is removed from sale because it is highly unlikely to be pure and it is very difficult to accurately identify young plants.

“We are currently working with DEFRA to understand the invasive potential of the cross and whether trade restrictions are justified.”

OATA recommends the following Gunnera species are not sold:

  • G. tinctoria (old name G. chilensis)
  • G. × cryptica
  • G. manicata (old name G. brasiliensis)

It is important to check the plants you are selling are correctly labelled and match the species sold.

OATA is also aware that there continue to be sales of Gunnera tinctoria – which is illegal to sell. If these are spotted they should be reported using OATA’s online reporting tool here.

The latest paper on the topic can be found here An investigation of large-leaved Gunnera L. (Gunneraceae) grown outside in Britain and Ireland | Sibbaldia: the International Journal of Botanic Garden Horticulture (rbge.org.uk)

Read the previous RHS paper here and another published on Plos One here.