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Grows up to 17 feet high. Do not touch! Blisters skin, long-lasting scars, and—if it comes in contact with eyes—blindness. Numerous white flowers clustered in an umbrella-shaped head that is up to 80 centimetres (31 in) in diameter across its flat top. Dark reddish-purple stem and spotted leaf stalks that are hollow and produce sturdy bristles. Giant Hogweed is a photo-toxic plant. Its sap can cause phytophotodermatitis (severe skin inflammations) when the skin is exposed to sunlight or to UV-rays. Initially the skin turns red and starts itching. Then blisters form as it burns within 48 hours. They form black or purplish scars that can last several years. Protective clothing, including eye protection, should be worn when handling or digging it. If skin is exposed, the affected area should be washed thoroughly with soap and water and the exposed skin protected from the sun for several days. Also called Giant Cow Parsley, but not the same as common, much smaller cow parsley, which is edible.