The gardener has 18 million legs
In the Amazon you can walk into a patch of forest that looks empty. One kind of tree, Duroia hirsuta, repeating like a planted field in the middle of the most crowded ecosystem on Earth. Local legend had a name for these places: devil's gardens, grown by an evil forest spirit.
The gardener is an ant. A 2005 study in Nature showed Myrmelachista schumanni lives inside Duroia's hollow stems and kills every other plant by injecting formic acid into its leaves. Leaves die within a day. It is the first herbicide ever found in an ant, and the poison is named for them: formica is Latin for ant.
The gardens are not clearings. They are nations. A typical one is a single colony, up to 3 million workers and 15,000 queens, farming the trees that house them. Gardens grow about 0.7% a year. The oldest one they dated holds 351 trees and is roughly 807 years old, begun around the year 1200. Still guarded. Still growing.
The emptiest-looking place in the loudest forest turned out to be the most tended. A spirit did plant it. The spirit has 18 million legs and a syringe of acid.