J.R.R. Tolkien tells us that Ents, those slow-moving, tree-like beings in his Lord of the Rings series, are the oldest living things that walk Middle-earth. One of my favorite scenes in The Two Towers, the second movie in Peter Jackson’s trilogy, is when Treebeard, the oldest of the old, finally gets angry enough about the evil Saruman’s ongoing destruction of trees to marshal his fellow Ents and destroy Isengard. With their ire properly roused, the Ents are able to break apart dams and walls; using their great limbs to heave enormous chunks of stone at their enemies, they wreak well-deserved havoc on the bad guys.

Legend has it that Ents were created to be “Shepherds of the Trees,” but it’s hard to know if they’re trees that have become humans or humans that have become trees. Ents come in all shapes and sizes, and they often resemble the specific kinds of trees they are charged with shepherding, or protecting—oaks or firs or rowans or what-have-you. They have bark-like skin, root-resembling fingers and feet, and their hair and beards are described as bushy, twiggy, and mossy, making personal grooming perhaps something of a challenge.

At least they can walk away when the need arises.

Ents’ rooted-to-one-spot counterparts, however, don’t have any options other than to make the best of where they find themselves. The ways they manage to do that are as magical as anything you might encounter in the forest of Fangorn. You’ve seen them yourself—trees embracing rocks, trees eking out a living from cracks and crevasses and nothing but thin air, trees clinging with gnarled roots and tenacity to eroding creeksides and crumbling road banks. How do they do that?

I didn’t know any Ents to pose the question to, so I resorted to Google and typed in “tree roots.” Root growth, it turns out, is opportunistic. Roots go where they can find what they need—water, nutrients, and oxygen—and the tree, unless it is on its way to becoming an Ent, has no choice but to hope they’re successful. There is no such thing as a shallow-rooted species or a deep-rooted species. Trees can grow deep roots, but root architecture is, well, rooted in climate conditions and in soil. Shallow, compacted soil will eliminate deep roots, but the tree still grows. Different species tolerate variations—good and bad—in soil structure, chemistry, and oxygen availability (thank you arnoldia.arboretum.harvard.edu), and the tree still grows.

According to some older studies—the ones that talk about the “square units of leaf surface” and the “grams of root present in a vertical column of soil”—trees such as oak that have large diameter xylem vessels (something akin to our own blood vessels) also have direct connections between a given root and a particular set of branches. Which leads to another interesting factoid: the roots of some forest trees sneak out beyond the canopy of their own limbs and intermingle with roots of neighboring trees. Are they chatting? Planning a move? Makes you wonder, doesn’t it?