Giant Hogweed, a poisonous plant which can be found in parks, footpaths and riverbanks, is spreading across the UK due to the recent warm weather.
The Royal Horticultural Society (RHS) said the the plans can reach over 10ft in heigh and poses a "serious risk" to people who are unaware of its potential for harm.
According to the PlantTracker app, the plant has been seen all over in Britain in recent weeks with a number of sightings in Sheffield and across South Yorkshire.
The RHS warned that people should not touch the plant as chemicals in the sap can cause blistering, pigmentation and long-lasting scars.
With the school holidays fast approaching, parents have now been warned not to let their children touch the plant.
Speaking to the Metro, River Trust expert Mike Duddy said: “If you don’t know what the plant is, it’s exceedingly dangerous.
"‘It is, without a shadow of a doubt, the most dangerous plant in Britain."
The plant has already injured several children across the country in recent weeks.
In 2015, ten-year-old Lauren Fuller from Thornbury was left with horrific third degree burns after picking up a piece of giant hogweek while fishing on Loch Lomond.
Within 24 hours of picking up the invasive plant she developed bright red burns on her hands and cheeks.
The RHS urged parents to wear gloves and cover their arms and legs when removing the giant hogweend and ideally wear a face mask.
They also said to wash any skin that comes in contact with the plant immediately.