Members of the public should take extra care not to come into contact with harmful weeds growing in parts of central Scotland, experts have warned.
Contact with the giant hogweed can cause skin to blister
Environmentalists say Japanese knotweed and giant hogweed can create problems to health and the environment.
Contact with the sap of giant hogweed, which can grow as tall as five metres, can cause skin to blister, especially in sunlight.
Stirling Landfill Trust wants residents in the area to look out for the plants.
The plants often take over riverbanks, causing problems for fishermen and walkers.
The giant hogweed's large flower stems clog rivers and weirs and in winter the weeds die back, leaving the bare riverbanks at risk of erosion.
The plants were originally brought to the UK by the Victorians - avid plant collectors who sought out exotic species from around the world.
Audrey Morrison, project manager with Stirling Landfill Trust, said: "Contact with the sap of giant hogweed can cause skin to blister, especially in sunlight therefore people are warned - especially children - to keep away from the plants.
"They can be a serious irritant if contact is made with the skin, causing recurring photo-dermatitis."
Stirling Council and Scottish Natural Heritage are supporting the trust to control and eradicate both of the fast-growing weeds across the Stirling Council area.
Giant hogweed is best treated now, at the start of the growing season, while Japanese knotweed should be sprayed when all the leaves are out. Plants should then be left to die off before being burned or buried.
Anyone who needs more information on how to deal with the weeds, or wants to report a sighting, should contact Stirling Council on 0845 277 7000.