Japanese Knotweed (Polygonum cuspidatum) 
is invasive. It originates from Japan. It was brought over here by gardeners who thought the flowers to be lovely and used the plants to occupy any area needing quick growth for hedging and such. This plants reeks havoc in all of Europe as well. These plants have been known to push through concrete and up into foundations of houses and industrial buildings rendering these properties to devaluate and hard to resell. Knotweed can grow 3 feet deep and sends suckers 7 feet away from its base to start new plants. Hard to eradicate by hand and spraying is found useless, only glyphosate injections per stem (!) seems to work. This is done in some municipalities by licensed landscapers. In Delta there is such a plan in place, here in Surrey we are told by the municipality to try just keep it out of our own yards! There are clusters of plants everywhere on the ridge, for instance; the bridge entrance to Joe Brown Park , the corner of 56th and 128, the empty lots on 56th and 125 street are riddled with it, on both sides north and south.
YET, these plants are edible! This plant can be eaten like rhubarb, mixed with apples in pies. I fact you can find lots of recipes on the web !
A compound derived in the root of this plant, ( and in red grapes as well) namely Resveratrol, has been synthesized as a nutritional supplement and used to treat Alzheimer’s!