As shown in the movie below, pinecones close when wet, and open again when they dry. But pinecone scales are made up of dead cells, which means their movements must be a mechanical response to getting wet. These scientists used a variety of imaging techniques, including X-ray tomography, to figure out how pinecones open and close in response to water. They found that pinecones direct water that lands on the outside "bract" scales towards the inner scales which respond and cause the cone to close before the whole pinecone gets soaked. This ensures the pinecones release seeds on dry days, giving the next generation the best shot at a wide dispersal. Treegonometree in action!
Journey of water in pine cones
"Pine cones fold their scales when it rains to prevent seeds from short-distance dispersal. Given that the scales of pine cones consist of nothing but dead cells, this folding motion ...
