I have never heard of this weed until now, but apparently it is taking over New York:
This noxious weed has spread across the state, threatening humans with sap that causes severe burns, blistering, permanent scarring and even blindness.
No, it’s not Mayor Bloomberg, but Giant Hogweed. The Wikipedia description matches the article. I think we need to close the Giant Hogweed loophole and make sure that people on the terror watch list cannot buy this plant.