Does resemble Himalayan blackberry (Rubus armeniacus). If you are in Coastal BC it may be a common weed, as it definitely is down here. Whitestem raspberry (R. leucodermis) is quite different, a raspberry type with chalky biennel canes.
By the way, that plant belongs to the family Rosaceae. Rubus is the genus to which it belongs. Cheers Harri Harmaja http://www.fmnh.helsinki.fi/users/harmaja/about_myself.htm
And by the way, Rubus discolor, R. armeniacus, R. procerus are all probably names for the same plant, its correct nomenclature having been disputed among Rubus experts for about the last half-century. In Australia we are now told that what we have been calling R. discolor or R. procerus is in fact R. anglocandicans. I wonder if that is the same as what you in other countries are now calling R. armeniacus?. The name R. fruticosus is different again. It is used as a "catch-all" name for a whole group of apomictic blackberry species from western Europe, including some that have become widely naturalized in other parts of the world. I believe it can also be used in a restricetd sense for just one of these species, but if so, that is not the same as R. "discolor". vbort44's middle picture is consistent with our local R. "discolor" in its fairly rounded leaflets and straight slender prickles, though it would need also to have a close mat of white hairs on the leaf undersides too. In New South Wales this is our commonest blackberry and worst weed, even in quite subtropical coastal areas, but it also has the most delicious fruit.
The last thing I heard about this was a UK expert came over here and said the common one here (being called R. discolor etc.) was properly R. armeniacus. Various authors have adopted the name, perhaps even starting before this individual appeared on the scene. The existing large population is thought to stem from a seedling selected by Luther Burbank in California and introduced as 'Himalayan Giant', it and others having been grown from seed of cultivated (naturalized?) specimens in the Himalayan region. Cultivar name 'Himalayan Giant' is still in use in UK, here the sexually reproducing, highly weedy descendents are called Himalayan blackberry.
