I have to admit that I didn't read the whole article, but did skim through... and it is 7Song and we know he does a great job:
Our Herbal CSW will pay particular attention to invasive medicinals like Japanese Knotweed
In order to supply herbs on a regular basis and in sufficient quantity, and in order to work in harmony with nature, I am particularly interested in harvesting "invasive weeds" as herbal medicines. Invasive plants are those that grow aggressively in areas where they were first introduced by man, either intentionally or inadvertently.
Colorado Flora - Eastern Slope - Third Edition by William A. Weber and Ronald C. Wittmann have Japanese Knotweed as Reynoutria japonica. They call it Japanese Buckwheat, and give Polygonum cuspidatum in parentheses. Polygonum is represented in the key, as is Fallopia. Fallopia is keyed out immediately as herbaceous vines (Black Bindweed). Polygonum is separated later from Reynoutria.
Garlic Mustard is a hated invasive, but primarily of cultivated areas and is also an important edible and medicinal.