Why Pinecones Open and Close in the Rain

Walk in the forest on a sunny day. Look at the pine trees. You see pinecones on the ground. They are open. They look like little wooden stars.

Now walk in the forest on a rainy day. Look at the pinecones again. They are closed. They look like tight brown fingers.

Why do pinecones change shape?

Pinecones have a very important job. They hold pine seeds. Pine seeds make new pine trees. A pine tree wants its seeds to travel far away. Wind carries seeds best when the weather is dry and sunny.

When the sun shines, the pinecones dry out. The scales on the pinecone open up. The wind blows the tiny seeds out of the open pinecone. The seeds fly through the air and land in the dirt.

When it rains, everything gets wet. Water makes the pinecones heavy. If the pinecones opened in the rain, the seeds would fall straight down. They would not travel. They would stay right under the big tree. Big trees block the sun. Little baby trees need sun to grow.

So, water closes the pinecone. The tight closed shape keeps the seeds safe and dry inside.

Pinecones are like tiny weather instruments. They do not have a brain. They do not know it is raining. The secret is science. Pinecones are made of two different layers of cells. The inside layer reacts to water. When water touches it, the inside layer bends. It pulls the scales shut. When the sun comes back, the water evaporates. The pinecone opens again.

Nature is full of clever tricks. Next time you see a pinecone, check the weather. Is it open or closed?

What do you see on the ground under trees in your area?