In the early-20th century, Luther Burbank was a botanical superstar. Tourists, foreign envoys, and celebrities flocked to his home in Santa Rosa, California, clamoring to see the marvels the “plant wizard” developed in his garden. For years, they watched in awe as Burbank rubbed his face on large, fleshy cacti pads that were seemingly smooth as silk. It was a demonstration of one of his proudest achievements: breeding cacti to have no spines.