THEY BROUGHT THEM IN SUITCASES and in trunks, tucked into the corners of boats and, later, on airplanes. Seeds that became rapini, cardoons, artichokes, cucuzza squash. Cuttings from knobby grape vines that flourished into backyard arbors. And, above all, bits of stick that grew into fig trees.

Starting in the late 1800s, when Italian immigrants poured into U.S. port cities, the Mediterranean trees took root in unexpected places: Astoria, Cleveland, Pittsburgh, Bayonne, cities whose cold-weather climates seemed hostile to the plant. Yet the trees grew, even if their owners had to wrap them in burlap or bury them underground so they’d survive the cold winters.