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how do I tell whether my triffid is russian vine or japanese knotweed?
By Thelil
United Kingdom 
Just moved house and have a shed load of triffid up and through a small tree. Can't get to the base to see the stems. Leaves are max 7cm long, trailing shoots red, clusters of flowers white. I can't distinguish from the web descriptions of each plant. Any tips? Will one or the other fruit, for example?
16 Aug, 2009
Answers
A pix. would definitely be a help in the i.d. Thelil
16 Aug, 2009
Its Russian Vine, I'm pretty sure - the trailing red shoots are a giveaway. Japanese Knotweed makes a "stand", rather like bamboo, which advances year on year and certainly doesn't twine or climb in any way.
16 Aug, 2009
It sounds like Russian Vine if it is in the canopy of a tree. As Bamboo says, the knotweed has more of a self supporting shrubby nature. The leaves of the vine are a yellowy green colour whilst those of knotweed are more of a reddish green.
Sorry, but no nice fruits to look forward to from either!
16 Aug, 2009
If your plant is truly climbing and twisting its way up and up through the tree...then the chances are high that it is a "Mile a Minute" Russian Vine. JK doesn't really twine itself round things. Also the Russian Vine does have clusters of flowers and the JK has long racemes.
Can you give us a picture so that we can help you more?
16 Aug, 2009