I think that sometimes a grove of trees is actually one organism. We see them as separate trees because we only see the part that's above ground.
Yes, you know Redwood tree roots are actually quite shallow? But their roots intertwine so much that they rarely fall over in storms. And Aspen seems to need other Aspen trees around it, or it just won't grow. You have to plant at least three Aspen together. Mushrooms actually have an underground system that can span for miles! The subterranean world is interesting.