Some of the UK’s most invasive weeds are often mistaken for harmless garden plants.

A study saw 600 Brits given pictures of 10 plants and asked to say whether they were weeds or flowers.

The most correctly identified weed was dandelion (92 per cent) with 57 per cent saying that troublesome ground elder was an unwanted invader.

Only half of people quizzed correctly said that invasive Japanese knotweed and bindweed were unwelcome. Just over a third (36 per cent) thought a buttercup was a weed.

The weeds in the study included dandelion, buttercup, daisy, white clover, cow parsley, stinging nettle, bindweed and ground elder.

One respondent said: “Despite being classed as weeds, I actively grow some in my garden. They are great for attracting wildlife. The main thing is to control them. So as soon as they start to spread I dig the new plants out.”

Spokesman Chris Bonnett, of www.GardeningExpress.co.uk which carried out the research, said: “There are some weeds that if you don’t identify and try and get rid of quickly, can cause a wealth of problems.”

WHAT IS JAPANESE KNOTWEED?

  • Japanese knotweed is a highly-invasive perennial which can regenerate from small fragments of deep underground rhizomes.
  • In summer, shoots can reach 7ft (2m) tall.
  • A number of home-owners have been featured on TV, saying that Japanese knotweed invaded their homes, making properties a nightmare to sell.
  • House-sellers are required by law to declare any presence of Japanese knotweed. This can put potential buyers off.
  • The weed can be dug out, but re-grows. Chemical weedkillers (such as those containing glyphosate) can kill top-growth, but it can take a lot of re-treatment to fully eradicate the weed.