“The hills bear all manner of fantastic shapes,” Charles Bessey observed, noting that they sometimes featured open pockets of bare sand in blowouts and were “provokingly steep and high.” Bessey was describing the Sandhills, the area of post-glacial dunes wrought by mighty winds in north-central and northwestern Nebraska. Aided by his botany students from the University of Nebraska (today’s University of Nebraska–Lincoln), he cataloged a treasure of plant species in 1892. Yet besides spurges and gooseberries, herbaceous plants such as smooth beardtongue, and grasses such as Eatonia obtusata, he found the potential for forestation. “He was convinced that the moist soil of the Sandhills would support forest growth,” the historian Thomas R. Walsh wrote. Nebraska had gained statehood in 1867 but still had enough untouched areas to be “a virgin natural laboratory,” as Walsh described it. And there were so few trees for wood, shelter, or shade. Bessey had been …