Legend has it that the term purple prose arose from the color of the ink employed in printing the earliest pulp fiction, and when Zane Grey wrote his best-selling potboiler Riders of the Purple Sage, he was surely swimming in it. He invokes the color in the first scene of the novel and then deploys it on nearly every other page, frequently as often as three times in the same paragraph.

It’s an odd choice for an evocation of the American West—in this case, that rare gambit of polygamous willfulness that goes by the name of Utah—because the eponymous high-desert shrub of the novel’s title is