He points first to "laziness, both individual or institutionalized." Like most Americans, book designers tend not to know all that much about the rest of the world, and since they don't always have the time to respond to a book on its own terms, they resort to visual cliches. Meanwhile, editors sometimes forget what made a manuscript unique to begin with. In the case of non-Western novels, they often fall back on framing it with "a vague, Orientalist sense of place," Mendelsund says, and they're enabled by risk-averse marketing departments.

"By the time the manuscript is ready to be produced, there's a really strong temptation to follow a path that's already been trod,” he says. “If someone goes out on a limb and tries something different, and the book doesn't sell, you know who to blame: the guy who didn't put the acacia tree on the cover."

He adds that the underlying issue can be more pernicious: "Of course, there are the deeply ingrained problems of post-colonialist and Orientalist attitudes. We're comfortable with this visual image of Africa because it's safe. It presents 'otherness' in a way that's easy to understand. That's ironic, because what is fiction if not a way for you to stretch your empathetic muscles?"

That's a reasonable diagnosis. But how to solve the underlying problem? Certain books are allowed to stand on their own; others—too often those by African, Muslim, or female authors—are assigned genre stereotypes. Mendelsund suggests that designers should start by initiating conversations with editors about what makes a book unique, so that they have something to respond to visually. And if that fails, and designers are pressured to use an offensive stereotype, Mendelsund says, "We can tell them that it's racist, xenophobic, whatever."

But change comes slowly. One day, Mendelsund predicts, there will be a best-selling novel by an African writer that happens to use a different visual aesthetic, and its success will introduce a new set of arbitrary images to represent Africa in Western eyes. "But right now, we're in the age of the tree," he says. "For that vast continent, in all its diversity, you get that one fucking tree."

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.