Usually when I feature a Weed of the Week it's something that grows in my own garden or allotment. But I haven't seen any giant hogweed anywhere in my area, and a good thing too.
Giant hogweed looks similar to cow parsley (which does grow in this area and almost everywhere else). But unlike its harmless lookalike, hogweed is huge - it can grow as high as 7m tall - and it has some nasty defences. If hogweed sap gets on your skin and is then exposed to sunlight it causes redness, itching and blisters. Just brushing past the plant can be enough to hospitalise you with severe burns. If the smallest amount of sap gets in your eyes you may go permanently blind. I can't find a reference right now but I am sure I have heard of people injured by swimming in lakes with hogweed growing nearby. The water of the lake became dangerous because of the sap in it.
I was reminded of giant hogweed by a news story about attempts to eradicate it in West Sussex. And I knew about it in the first place because of a Genesis song called The Return of the Giant Hogweed.