Schonwald, a Chicago journalist, focuses on three broad areas of interest: the salad revolution, which has brought new ingredients to the table — think radicchio, and weeds, and greens in sealed bags — and altered mass tastes as well as those of elite foodies; efforts to grow meat in vitro, i.e., in the laboratory rather than in the cow; and the rise of land-based fish farming. Every once in a while his prose turns a little flippant, and he does use the first-person singular to excess, but he has come up with a great deal of interesting information, much of which will surprise people who eat food without giving much thought to where it comes from.

A decade and a half ago, when Schonwald was 26, his mother served him “the most transformative meal of his life” while he was visiting her in Wisconsin. It was a salad called “spring mix” that she had bought in a plastic bag at a nearby grocery store. He thought it was delicious and in time came to understand that it was part of a genuinely significant phenomenon: “Bagged salad was a game-changer: it changed the American salad eating experience, ended a half century of iceberg’s totalitarian-like grip on the salad bowl, and brought arugula, frisee, red oak, green leaf, and mizuna to places like Kenosha, Buffalo, and Lubbock.”

So off he went to Salinas, the California city made famous by the early novels of John Steinbeck, most notable now for being “the primary city of a valley nicknamed the ‘World’s Salad Bowl.’ ” Here’s something I never knew, and you probably didn’t either:

“For most of the past sixty years, the ninety-mile-long Salinas Valley has single-handedly accounted for more than 90 percent of the lettuce eaten in the United States. These days, more than 4 billion pounds of greens are grown in the Valley. Salinas is also the nerve center of the industry; it’s the home base of companies like Fresh Express and Dole and Mann Packing, the Apples and Microsofts of the salad world. In other words, Salinas is not only where our leafy greens are grown; it’s where the decisions about our salads are made.”

It was Fresh Express that “started introducing bagged salads to consumers in 1989,” extending the shelf life of delicate greens and posing real rivals to durable but usually tasteless iceberg lettuce. What, Schonwald wondered, is Salinas Valley looking to do next? A few people there believe that radicchio is the salad of the future. It comes in more varieties than the unappetizing red variety that pops up in salad bars and “spring mix” bags, but efforts to gain popular acceptance of those varieties have met with little success. Schonwald is optimistic about the overall future of salad, though, because the “agrigiants” of Salinas are quick to capitalize on changing tastes and to alter supply to meet altered demand. Disbelievers are referred to the nearest salad bar, where there’s a lot more in the lettuce bins than chopped romaine.