Giant hogweed gone to seed

A beast of a plant. If the sap gets on your skin it can make it intensely photosensitive. This can lead to vicious burns and blisters when the skin is exposed to sunlight and the effects can recur for months or sometimes years. 
A giant hogweed seedhead can produce up to 50,000 seeds which can still germinate after 15 years. 
Stay well clear, and don't balance on a slope above it trying to get a close up photo of it like some idiots do.