How does a pine cone open?

Question

When a pine cone is wet, it remains closed. However, when it's dry it opens again. From the perspective of physics or biomechanics, what is the mechanism that allows a pine cone to open and close as I've described?

Answer 1

Seed bearing pine cones have scales on them. These cones close and open in response to the degree of humidity in their surrounding environment. Under warm and dry conditions, these scales on the cones open up and the seeds inside them are released. In damp and cold environmental conditions, these scales on the cones close up. So these scales on cones move in response to the degree of humidity.