Blackberries are a scourge in western Oregon, really hard to get rid of. They spread over the top of other plants and crush or smother them. They spread (and spread and spread) from their roots and re-root where their branch tips touch the ground. Birds can spread the berries over long distances. (Do you notice the repeated word “spread?”) Their barbed thorns are absolutely vicious.
But oh, come late summer, those berries! Juicy sweet and warm with sun, eaten right from the vine—no other fruit tastes so purple!