While we knew plants responded to changes in weather, we must have missed the day our teacher showed the class that we could use a pinecone to gauge humidity.
Now, technically, we feel like walking out into a humid day is enough to make us say, “wow, it’s humid out here.” End of story. But let’s say you’re having a disagreement with a friend about whether it’s humid or just simply hot. THAT’S when it might come in handy to ask a pine cone.
Pine cones open up their scales when the weather is dry (presumably, the evolutionary logic is so their seeds won’t get bogged down too close by and compete with one another when they grow). When the weather is humid, they close back up.
When pine cones are wet in general, their scales swell shut. The outer parts shrink when they’re dry, causing them to pull away from the cone. (This is also why crafters will heat pine cones in the oven before using them. And if you rinse an open pine cone, it will close again.)
Of course, nature is finicky and can take a minute to get the hint, so don’t ask too early in the morning since it may take them some time to get the hint and respond appropriately. But next time you need a science fair project, that seems like a cheap way to do it!
If this is confusing, or you’d simply like to see how it works, check out this oddly mesmerizing video:
Source: “Pinecones close when it rains. Here’s how they do it!” — Discover
