So the Counting Pines avoided all this by letting other vegetables do their evolving for them. A pine seed, coming to rest anywhere on the Disc, immediately picks up the most effective local genetic code via morphic resonance and grows into whatever best suits the soil and climate, usually doing much better at it than the native trees themselves, which it usually usurps.

What makes the Counting Pines particularly noteworthy, however, is the way they count.

Being dimly aware that human beings had learned to tell the age of a tree by counting the rings, the original Counting Pines decided that this was why humans cut trees down.

Overnight every Counting Pine readjusted its genetic code to produce, at about eye-level on its trunk, in pale letters, its precise age. Within a year they were felled almost into extinction by the ornamental house number plate industry, and only a very few survive in hard-to-reach areas.

The six Counting Pines in this clump were listening to the oldest, whose gnarled trunk declared it to be thirty-one thousand, seven hundred and thirty-four years old. The conversation took seventeen years, but has been speeded up.

"I remember when all this wasn't fields."

The pines stared out over a thousand miles of landscape. The sky flickered like a bad special effect from a time travel movie. Snow appeared, stayed for an instant, and melted.

"What was it, then?" said the nearest pine.

"Ice. If you can call it ice. We had proper glaciers in those days. Not like the ice you get now, here one season and gone the next. It hung around for ages."

"What happened to it, then?"

"It went."

"Went where?"

"Where things go. Everything's always rushing off."

"Wow. That was a sharp one."

"What was?"

"That winter just then."