Japanese knotweed (polygonum cuspidatum) is an extremely invasive non-indigenous plant and gardeners who know it are generally distressed to find it on their patch. However, today I spotted this deliberately positioned specimen, growing happily in the Hortus Botanicus, Amsterdam. It’s even got an identification plate!

I once saw Japanese knotweed growing into a house which was being auctioned, yes into it, through the walls and under the floor! Needless to say, I didn’t make an offer to buy the place.

Seeing the plant reminded me that it is edible and apparently rather tasty too. According to the late Maida Silverman in her book, A City Herbal, it can be harvested and eaten in the same way as bamboo shoots, at this time of year. New York forager Steve Brill seems to like it, likening it’s taste to rhubarb. He also mentions it’s suitability as a companion plant, due to pesticide qualities. Personally, I don’t find the plant calls me to try it and I worry that by harvesting young shoots, the plant would further proliferate, in an attempt to survive. I hope I’m wrong because there is plenty of this plant growing in Amsterdam and I do love rhubarb crumble! What a great foraging plant this could be.

I’d love to hear from anyone who has tasted this plant. It is said to be quite tender, when cooked and to act as a gentle laxative. I’m also keen to know if harvesting, without pulling up the roots, would increase the plant’s chances of survival.

I wrote to Steve Brill about the harvesting issue. Here’s his reply…

On Apr 18, 2012 1:16 AM, “Steve Brill” wrote:
>
> Hi Lynn,
>
> Thanks for writing. As far as I can tell, it spreads wherever it can whether or not it’s harvested.
>
> Happy Foraging!
>

So knotweed crumble, here I come!