Fallopia sachalinensis - is it the real plant?


In 2006 I was at the Botanical Gardens of Leiden University (Leiden Hortus) taking some photographs.

One of the plants I took photos of was the Fallopia sachalinensis, or Giant Knotweed. A few months later - while checking the statistics of my photos - I noticed quite a few visits from one particular website, Invasive Species. Curious to find out what the blogpost was all about, I checked it out.

It seems that people-in-the-know are not quite certain whether the botanists at the Leiden Hortus have tagged this plant correctly. The owner/author of the blogpost has tried to contact the Leiden Hortus, but never received a reply.

I have not really paid close attention to this photo, until today when I received a message via flickr. Someone has asked to use my photo for research. They want to use my photo (pictured) to help them identify similar species. Of course they are more than welcome to use it, but I have referred them to the discussion on the validity of the name of this particular plant.

The message I received was as follows:

[…] I’m working with the New England Wild Flower Society to put together a comprehensive online identification key to the plants of New England, USA. We have a grant from the National Science Foundation for the project. I am in the process of building the image library for the website, and we are still in need of many photos of the various species found in this part of the world. I am writing you because your picture of the stems of Fallopia sachalinensis would be perfect for our identification key. […]

I am very curious now to find out whether this plant is indeed the Fallopia sachalinensis. Frankly I find it hard to believe that the Leiden Hortus is incorrect.

Any biologists/botanists who can help me?