How the lily blooms

This week scientists from Harvard and The University of Science and Technology of China have worked out how the lily pops open when it blooms.

They looked at the Asiatic lily, otherwise known asLilium casablanca. Researchers Liang and Mahadevan marked the bud with dots along the inner petals and outer sepals; those are usually the green leaf-like parts underneath the petals. They then set up camera to track the dots as it grew.

Publishing in PNAS, they found that the petal and sepal edges lengthened 40 per cent more than the midribs (these are the central veins in a petal or leaf). This disparity in growth created that characteristic wrinkling at the edge of the petal.

The authors say that this difference in growth causes stress to build up inside the bud and the forces eventually exceed those keeping the bud closed, causing the flower to burst open. Previous studies have argued that it is actually the midrib which causes the popping-open of the lily so, to test this, the researchers actually shaved it off the petal. Lo and behold, it still popped open as normal.

Why is this important? The authors argue that it can be mimicked in technology for designing thin film motors which would need blooming explosions on a small scale.