The unusual mathematics that gives rose petals their shape

As rose petals grow, they curl outwards and form pointed corners. The pattern is related to extrinsic, rather than intrinsic, geometry.Credit: bibi57/Getty The growth of rose petals exploits a geometric trick previously unobserved in nature, physicists have found. Using theoretical analysis, computer simulations and experiments with rubbery plastic sheets, they established that as the petals curl outwards, mechanical feedback regulates their growth, leading to the formation of rolled edges and pointed corners at their tips. The findings, described in Science on 1 May1, could one day have applications in engineering and architecture. “You might learn new principles and then implement them in manmade structures,” says Eran Sharon, an experimental physicist at the Hebrew University of Jerusalem. Nature’s patterns Geometric patterns are known to affect developing organisms. But in all previously observed cases, the principles had to do with the ‘intrinsic’ geometry of surfaces. Intrins ... Read full article.