Giant hogweed is easily distinguishable from the similar native hogweed and cow parsley due to its sheer height which can reach three to five metres.
Where is it found?
It is most commonly found in areas of damp soils, such as river banks.
How does it spread?
Each flower head can produce up to 50,000 seeds which are easily dispersed by flood water, meaning it can quickly take over an area. Its seeds can live for up to 20 years, so treatment must be continued until the soil seed bank is fully exhausted and no further growth is observed.
Is it harmful?
Giant hogweed contains a sap which irritates skin when it is exposed to sunlight. Symptoms are usually noticeable within 24 hours and include blistering and swelling on the skin, which may be made worse by over-exposure to the sun.
If you come into contact with it, cover the affected area immediately to avoid exposure to the sun. Wash the area with cold water. If blistering occurs or the contact was with the eyes, you should seek medical advice.