By Fiona Roberts
A monster plant that can cause blindness just by touching its sap is spreading across New York.
State officials are warning residents to watch out for infestations of the dangerous plant, which can grown up to 12ft and has flowers the size of umbrellas.
Teams are working across New York to destroy the monster weed, as its sap can cause severe blisters and permanent scarring.
Dangerous: Giant hogweed plants can grow up to 12ft high. The weed's sap can cause painful blisters, permanent scarring and even blindness
So far the Department of Environmental Conservation has identified 944 known sites from Nassau County in the east to Chautauqua in the west.
The department is urging New Yorkers to be on the look out for giant hogweed, but warning them not to touch it.
The plant's sap is so corrosive that just brushing against its bristles can cause painful, burning blisters.
It produces the reaction when combined with perspiration and sunlight.
Invasion: This map shows the spread of giant hogweed across New York State. So far 944 sites have been identified
WHAT TO DO IF YOU TOUCH GIANT HOGWEED
Wash the affected area thoroughly with soap and cold water as soon as possible.
Keep exposed area away from sunlight for 48 hours.
If a reaction does occur, applying topical steroids early on can reduce the severity of the reaction.
If sap goes in eyes, rinse them with water and wear sunglasses.
If a reaction has occurred, the area of skin may be sensitive to sunlight for a few years, and you may want to apply sun block or keep the affected area covered from the sun when possible.
See a physician if you have a reaction or any questions.
Source: Department of Environmental Conservation
It can also create red blotches, which are painless, but later develop into purple or brown scars that can last for years.
The huge plants have hollow, ridged stems with dark red patches, and large leaves which can grow up to five-feet wide.
Its flowers can reach up to two-and-a-half feet in diameter - the size of umbrellas.
It's the fourth year in a row the dangerous plant has invaded the state, and the department is desperately trying to control it.
Officials have set up a hotline for residents to call if they spot anything they think could be giant hogweed.
Callers are asked to send in photographs of the plants for identification, then one of the department's six 14-strong control crews will then be dispatched to destroy it.
Sites with fewer than 400 plants will be controlled by hand cutting the roots and removing the seed heads. Those with more than 400 will be controlled with herbicide.
The plant comes from the Caucasus Mountain region between the Black and Caspian Seas.
It was introduced to Europe and the UK in the 19th century as an ornamental garden plant, and was brought to the U.S. in the 20th century.
Since then, it has become established in states including New York, Pennsylvania, Ohio, Maryland and Maine.