It may be far in the future, but there's some kind of logical way to get from where we are to where the science fiction is.
A tree is alive, and thus it is always more than you can see. Roots to leaves, yes-those you can, in part, see. But it is more-it is the lichens and moss and ferns that grow on its bark, the life too small to see that lives among its roots, a community we know of, but do not think on. It is every fly and bee and beetle that uses it for shelter or food, every bird that nests in its branches. Every one an individual, and yet every one part of the tree, and the tree part of every one.