Chinese and American scholars uncover the mystery of lily blooming

Lily is pure and solemn The history of human love can be traced back to ancient Egypt in 3000 BC In the Southern Dynasty of China, Emperor Xuandi of Liang praised lilies for their "multiple leaves, no different colors of flowers, low dew and low willow" However, how lilies bloom gracefully is not well known On March 21, the Journal of the National Academy of Sciences published the results of the cooperative research between Professor Liang Haiyi of University of science and technology of China and Professor Ma hudwen of Harvard University of the United States, which showed the truth of Lily opening According to the whole process of lily blooming recorded by the camera, they found that the edge of the white composite petal was longer than the middle part, and this uneven growth characteristic produced a great force on the petal, and finally made the flower bloom According to the traditional view, the central vein of lily petals is curved outwards, or the inner side of petals grows faster than the outer bimetallic sheet, which is the root of Lily opening "It seems that we can understand the curvature of petals, but it can be found that the edge of lily petals gradually presents wavy folds in the process of opening, which cannot be explained by the traditional view point," said Dr Liang Haiyi, a newly introduced professor of "Hundred Talents Program" in the Department of modern mechanics, University of science and technology of China For this reason, scientists mark the top points along the edges and midvein of the flower bud petals of perfume lily to measure the subtle changes in the size and shape of flowers from the bud to the bloom They immerse the undeveloped perfume lily bulbs in water for 4 and a half days, until the flowers are completely open It was found that the growth rate of petal edge was more than 40% faster than that of midvein Therefore, scientists believe that the difference in petal growth speed makes the edge subject to great expansion force and the middle area subject to tension Under the effect of internal force caused by this uneven growth, petals gradually bend outwards, gradually fold on the edge of petals, and finally fully bloom Further theoretical and numerical simulation revealed the change of petal internal force during flowering Scientists are surprised to find that the edge expansion force can not effectively bend the petals at the early stage of bud opening, but it can effectively bend the petals outward after reaching a certain critical point, which is exactly what the lily needs for rapid opening In 1790, German naturalist John Goethe once declared that leaves and flowers are homologous in the article "the change of plants" Indeed, our previous work showed that edge overgrowth resulted in a variety of leaf morphology The same marginal overgrowth mechanism of leaves and lilies is the first time in 200 years that John Goethe's prediction has been confirmed at the plant organ level " "Nature once again shows us a highly evolved masterpiece, which provides a new design principle for bionics," Liang said