Japanese knotweed, fallopia japonica or sachalinensis, has arrived in the UK and established itself over the last few years; huge and costly efforts are being made to eradicate it and there are even proposals to introduce an insect from overseas which might act as a predator and eat the invader.
This seems very risky. Supposing this evil foreign bug takes a fancy to one of our honest British plants, and we woke up one morning to find the country denuded of runner beans, delphiniums or even oak trees?
It might be better to consult the ever-useful Oxford Companion to Food, which notes in its article on Knotweed: "The young shoots make a pleasant vegetable, whose acidity can be tempered by the addition of a little sugar in the cooking. Or, they can be steamed and made into a purée, which can in turn serve as the basis of a sweetened cold soup. The mature stems, peeled, can be treated like rhubarb and it is even possible to make jam or a pie from them".
The trouble is that all this sounds pretty unappetising and it is hard to imagine that people will chomp their way through enough of the stuff to make any substantial inroads into the hundreds of acres of 2-metre shoots already growing. I suppose the TV chefs will have to tempt us with it, demonstrating Knotweed à la Japonaise, Barbecued Knotweed Kebabs or even Knotweed Crumble.