Why Are Some Pinecones Open And Others Closed?

If you’ve ever been in an area with any amount of evergreen trees, you’ve probably noticed that some pines cones look more open than others: the “teeth” of the some cones are separated so that each is starkly defined, with gaps in between, while others are closed up tight. It is one of those nagging outdoor science mysteries, often explained away through passed-down, half-remembered information. (Personally, I used to think open pinecones meant that someone– or something— had eaten all the pine nuts out of it, and I never really questioned that assumption– or the mechanics of how that would even work– until recently.)

There’s a simple explanation for why some pinecones look open and others do not: humidity. When it’s dry out, the scales open to release the seeds (as dryness portends more favorable conditions and increased chance of survival). When the air is damp, the scales close again. Interestingly, this is a passive movement on the part of the pinecones, as mature pinecones are, on a cellular level, dead. (Very much in the spirit of the season!) For those who prefer open or closed pinecones for crafts, you can simply dip pinecones in water to close the scales, and place them in the oven (or out in a dry, sunny spot) to open them up.

(And for the record, pine nuts are harvested by drying pinecones– just in case you were wondering.)