I regularly drink coffee with some Brittania Beach locals, who have been frustrated trying to identify this seemingly non-native plant so they've asked me to try to get some help from the botany community at UBC. They tell me the plant also smells slightly minty. If you need further pictures i can get them. but i thought i'd start with a leaf! it is quite large- larger than my hand.
Any more pics? 3 pics as follows should do the trick: The whole plant where it's growing. Then a close up of the leaves, flowers, fruit w.h.y. Last a pic of the stem and how the leaves join it.
As a guess - the picture is really not very informative sjolly! - this might be Himalayan Knotweed (Persicaria wallichii). I am probably wildly wrong, but I am used to that :) Get some more pics and all will become clear. Edit: Or, maybe American Pokeweed (Phytolacca americana)