Japanese knotweed could be more effective than antibiotics at tackling problem of Lyme disease | Daily Mail Online
Interesting. I had thought it would be good if existing plants were used, rather than people planting the stuff to be used for the antibiotics. But there is a comment from an urban forestry technician below this more informative blog: The Essence of Herbs: Japanese Knotweed in the Treatment of Lyme Disease saying that "[f]or every plant you dig up more are created and I have seen people wash the roots off in river systems which really add to the problem." I couldn't find anything in the original article sayinghow it's administered; from the blog article, it seems it's orally, as a decoction or tincture, though the forestry person suggested buying the powdered form in capsules.
Since the "Japanese" knotweed of the Pacific Northwest, Great Britain and wherever else this may be the case is usually Bohemian knotweed I wonder if that has any bearing on this topic. That is if the stock grown for the drug has to be the true Japanese knotweed or if the hybrid can be used in its place.
See Hu Zhang/虎杖/Japanese Knotweed Identification This article isn't as specific as I'd want in answering that, but the person who wrote it is interested in it from a medicinal standpoint and mentions that it is important to distinguish those two and Polygonum sachalinense. He does include "lyme disease" among his tags and considers the non-cuspidatum ones to be adulterations. He gives a good description of P. cuspidatum, and a detailed comparison of the two species and the hybrid, though much of the hybrid description seems to be stuff like "intermediate between the two". There are very detailed photos.
The three are treated in key format under Fallopia in the 2018 edition of Flora of the Pacific Northwest, where P. cuspidatum is listed as a synonym of F. japonica. With both the Japanese and hybrid knotweeds being described by the Flora as "aggressive" within the region. However 10 years prior A. L. Jacobson had reported in Wild Plants of Greater Seattle - Second Edition that the hybrid was "more common than either parent" there.