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CNR: Alamanacco della Scienza

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N. 6 - 30 mar 2011
ISSN 2037-4801

International info   a cura di Cecilia Migali

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How the lily blooms  

Mathematics has 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, conducted at Harvard's School of Engineering and Applied Sciences (Seas) contradicts earlier theories regarding growth within the flower bud. Published online this week in the Journal Proceedings of the National Academy of Sciences, the findings explain the blooming process both theoretically and experimentally.

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.

Now, however, mathematics has 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 lily's bloom.

The research, conducted at Harvard's School of Engineering and Applied Sciences (Seas), contradicts earlier theories regarding growth within the flower bud. The petals, in fact, behave like leaves. Published in the journal Proceedings of the National Academy of Sciences, the findings characterize the blooming process using mathematical theory, observation, and experiment.

"That differences in planar growth strains can lead to shape changes has been known for some time," says principal investigator L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics at Seas. "But showing that it is at work and dominant in lily blooming is new, as our measurements and simple theory show."

"What is most surprising is that a subject that is so rich in metaphor-the blooming of a flower-had been studied so little from a quantitative perspective."

The researchers used observation and experimentation to measure growth in various parts of the petals and to determine which types of growth are necessary for blooming. They then characterized the process mathematically in order to quantify, synthesize, and generalize their observations beyond the specific instance.  

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