From the Field Notes of Colonel Aubrey Fitch-Harrington, FRS

Observations Upon the Fauna of Southern Africa — Volume III (In Preparation)

“The Shepherd’s Tree (Boscia albitrunca) has the deepest roots of any tree. The deepest confirmed root system: sixty-eight metres below the surface in the Kalahari. This is not the length of a long root but the depth — sixty-eight metres down into the earth, past the surface geology entirely, into the ancient water that sits below the Kalahari sand. The tree is a modest tree of unremarkable dimensions. It does not announce what it is doing below the surface. The author is standing above sixty-eight metres of root and looking at an apparently ordinary grey-green tree and Cetshwayo is pointing at the ground.”

“What is down there,” Cetshwayo said.

He had pointed at the ground in the way that indicated something specific rather than the general ground. The Colonel looked at the shepherd’s tree, which was a modest tree, a grey-green tree, a tree of appropriate dimensions for its visible world, not the kind of tree that prompted pointing at the ground beneath it.

“The water,” Cetshwayo said. “Sixty metres down. Perhaps more. The tree has found it.”

The Colonel looked at the tree again. Then at his field notes, where he had been writing about the Kalahari’s apparent absence of surface water. He had been writing about the absence of water.

Below him, sixty-eight metres down, the tree had water.

It had found it decades ago — centuries ago, probably, for a tree of this size — and had put its roots down through the Kalahari sand and the rock formations beneath it and the deeper geology beneath that until it found the ancient water that no rain replenishes in the short term. The water the tree was drawing on had been accumulating in the deep Kalahari for longer than any surface record.

He wrote: The shepherd's tree has roots sixty-eight metres deep. The author has been writing about the Kalahari's water scarcity for the duration of the Kalahari section of this volume. The tree has been drawing on water sixty-eight metres down while the author wrote about the scarcity above. The scarcity is a surface condition. Below the surface is not scarce. The tree knows this. The author is learning.

He sat with the notebook for a moment and tried to make the number real in terms he understood. Sixty-eight metres. He knew buildings of that height. He knew geological cross-sections in field reference books. He knew, in the abstract, what sixty-eight metres meant. The abstract was not the same as standing above it.

He knocked on the trunk. He acknowledged immediately that this was not a scientific procedure. He knocked anyway. The trunk was solid. It gave nothing and told nothing. Below it the roots went where they went, into the water that had been there since before the Kalahari was the Kalahari, drawing on a supply the surface did not know was there.

Cetshwayo watched the knocking with the quality of attention he applied to the Colonel's more unusual investigative methods.

"It knows where the water is," the Colonel said, as much to himself as to Cetshwayo.

"Yes."

"Has always known."

"It found it," Cetshwayo said. "Then it stayed."

The Colonel looked at the leaves, which were small and dense and a grey-green that matched the Kalahari's colour almost exactly — the colour of something that has adapted to its landscape over a very long time and stopped distinguishing itself from it. He wrote: The shepherd's tree is grey-green because the Kalahari is grey-green. The roots go sixty-eight metres because the water is sixty-eight metres down. The tree is, in every visible dimension, an expression of the exact landscape it occupies. The author has been walking past an expression of the Kalahari without seeing the Kalahari. He has been seeing a tree of unremarkable dimensions. He is revising what he was seeing.