The “lily white” has inspired centuries’ worth of rich poetry and art, but when it comes to the science of how and why those delicately curved petals burst from the bud, surprisingly little is known. Mathematics has now revealed that differential growth and ruffling at the edges of each petal — not in the midrib, as commonly suggested — provide the driving force behind the blooming of the lily. The research contradicts earlier theories regarding growth within the flower bud. The findings explain the blooming process both theoretically and experimentally.