Pinecones close when it rains. Here’s how they do it!

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

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