Pollen grains are beautifull structures that show an amazing range of variations between different species of plants. |They have an outer wall, which is stiff, with one or more openings for the exit of the germinating pollen tube. This tube carries the reproductive cells from the pollen grain to the ovules inside the pistil. The openings are covered by a thin membrane designed to break under the pressure of the growing tube.

The most exiting physical phenomena behind pollen grains is their ability to close the openings by deforming the outer wall. Pollen grains detect changes of humidity and close the gates under dry conditions to keep water inside. The opposite happensÊ when humidity conditions are fair enough; the gates are opened and the tube grows.The physical mechanism is a mistery, but it seems that the deformation of the wall is inextensional and can be described by using Elasticity and Geometry. This current project intends to explain the different types of pollen grains by using these simple assumptions.

People involved:
Jacques Dumais (Harvard University)
Silas Alben (Harvard University)
David Nelson (Harvard University)
Enrique Cerda (Universidad de Santiago)

References

"Pollen: The Hidden Sexuality of Flowers", Rob Kesseler and Madeline Harley, Papadakis Publisher (2004). Palynological Database: http://paldat.botanik.univie.ac.at