I live on the north side of Mt. Scott in outer east Portland, at about 650 feet elevation. I walk down the street to harvest Himalayan blackberries, and I have cultivated native Pacific blackberries by weaving those vines through my wire fence out back (my backyard borders maple-tree woods). While hiking through these woods, I've come upon a berry that looks like a blackberry, but it isn't Himalayan or Pacific -- its berries ripen much later than Himalayan, their vines are reddish and not nearly as stout as Himalayan, and the leaves have sawtooth edges. I haven't seen any other plant like this in my hikes through these woods. The plant is confined to an area of ten feet in diameter, and sits on the southern edge of the woods and adjacent open space. My Google search suggests it is a European blackberry. Can you tell me what this plant is, and why it hasn't proliferated like Himalayan or Pacific blackberries? (I've attached photos.) Much appreciated, Gary