“More than any other single trait, it is the apple’s genetic variability—its ineluctable wildness—that accounts for its ability to make itself at home in places as different from one another as New England and New Zealand, Kazakhstan and California. Wherever the apple tree goes, its offspring propose so many different variations on what it means to be an apple—at least five per apple, several thousand per tree—that a couple of these novelties are almost bound to have whatever qualities it takes to prosper in the tree’s adopted home.”