By Barbara Bray Oakland (MI) Chapter
Last April, as I was weeding in my new prairie planting, I heard a curious popping noise behind me. I rose to my feet, turned around, and followed the sound over to the pine trees. I stood there for a moment, puzzled by the noise, and then it hit me the sound was from the pinecones on the trees snapping open! Pine trees are the green in our winter landscapes and they provide wood for our houses and pulp for our paper, but sometimes, if you listen closely, you will hear their secrets.
Have you ever seen pine tree flowers? If your answer is no, then you are very observant. You will not find any, because pine trees dont have the sort of flowers that we would usually recognize. They do, however, have special male and female reproductive structures. The male cones look like dust-coated fingers in late spring. The female cones are tiny, pinkish structures at the ends of new growth. The male structures elongate, and yellow pollen floats away on the wind to cover sidewalks, decks, and cars. Luckily, some of that pollen also lands on the female nubs, which will develop into mature pinecones full of little winged seeds.
The scales on a pinecone can be used to measure humidity (or moisture) in the air. The scales on pinecones are of an uneven thickness. If there is a lot of moisture in the air, the cones soak it up and the dampness causes the scales to curl inward. In dry weather, the scales will curl outward, thus opening the cones. This important attribute protects the seeds in the cones from dispersing into a wet environment where they could rot. You can explore this surprising adaptation with your child in the following experiment.
You will need one pinecone and a container of water. Look closely at your pinecone. Does it have any seeds inside? Place the pinecone in the water and wait for an hour. After one hour, how has your pinecone changed? Now, take the pinecone out of the water and place it in a sunny, warm spot. Ask your child to make a prediction on how long it will take the pinecone to open again. Then observe the pinecone periodically. Does it take one hour for the pinecone to open? Two hours? Four hours? Or longer? When you have finished with this experiment, try it again with different pinecones. If the cones are old, will they react in the same way? What if the cones have been painted (such as in old crafts or decorations)? Does this work with any other cones?
Have fun, and remember to listen to your pine trees!
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Updated: Jun 12, 2005.