Play with Your Pine Cones

Kathy J. —  January 18, 2013 — 2 Comments

I was walking under some pine trees near the Learning Campus and I took a picture of the cones I found.

PHOTO: The ground under the pine tree is covered in dry, brown pine needles and cones that are open, closed and in between.

I found two different kinds of cones on the ground under the pine tree.

When I was young, I noticed there were two different kinds of cones — some solid cones like the three in the lower left corner of the picture, and others are more like the open, branched cones at the top. I thought the pine tree made two different kinds of cones. Actually, they are different forms of the same kind of cone. I will show you how this happens.

I took three cones that were the same size and shape. Then I soaked one cone in a bowl of water. 

PHOTO: Pictured here are three pine cones of similar size, shape, and color.

I started with three pine cones of the same kind, shape, and size.

 

PHOTO: One pine cone is floating in a white bowl full of water while the other two are resting on the right side of the bowl.

I placed one cone in a bowl of water. It slowly began to change.

 

PHOTO: One pine cone is in the white bowl, now almost fully closed after ten minutes, while the other two are dry and unchanged at the side.

After about ten minutes, the wet pine cone is almost completely closed, while the dry cones are still open.

 

PHOTO: A wet, closed cone is shown next to a dry open cone.

Wet cones are closed, dry cones are open, and that is why cones from the same tree come in different shapes.

Then I let the wet and dry cones sit on my desk overnight. Guess what happened. Try it yourself to get the answer! Go outside and find a pine, spruce, or other conifer tree. Bring pine cones from those trees inside and watch them over time as they adjust to the warm, dry conditions in your home. Put one in bowl of water and see what happens. Let it dry and see if it changes again. 

What is going on here?

Pine, spruce, Douglas-fir and other conifers are so named because they produce cones that bear their seed. When conditions are favorable for the seeds to fall and grow, the cones open and release them. The seeds have the best chance to survive when the air is dry and windy, so they can blow to a nice fertile spot away from the shade of the mother tree. When conditions are wet and not so good for a traveling seed, the cones close to protect them.

Though the cones I found under the tree had released their seeds a long time ago, they still responded to the moisture levels of the ground and air. These cones were in between being damp from the rain over the weekend and drying in the sun.

Pine cone history

By the way, all conifers belong to a group of plants called gymnosperms. This means they produce “naked seeds” — seeds that are not contained within a fruit. Conifers do not grow flowers. Before there were dinosaurs on the planet, all plants reproduced by either spores or naked seeds. The seeds of some conifers can take up to three years to mature. Flowering plants (angiosperms) have a much more rapid reproductive cycle. Some angiosperms flower and produce mature seed in just one week. Understanding how cones and flowers have evolved is what Dr. Pat Herendeen is trying to figure out from plant fossils.


©2013 Chicago Botanic Garden and my.chicagobotanic.org

Kathy J.

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Kathy J. has been learning and teaching kids about nature for more than 20 years. She collects bugs, watches squirrels, does not get a rash from poison ivy, practices “snacker” behavior in winter, and is always on alert for interesting plants and animals. When she’s not watching something in the trees or spending time with her teenage daughters, she’s overseeing programs for teachers and students at the Garden.

2 responses to Play with Your Pine Cones

  1. This demonstrates something I did not know about pine cones. I have a dog that is allergic to pine, spruce according to a recent allergy test. What part of these trees and when would they be giving of pollen that would cause a skin allergy on my golden retriever?

  2. Pine and spruce trees both produce two kinds of cones. The cones in this blog are all “female” cones that produce seeds.

    Male cones, which produce pollen, swell and open in spring, releasing a LOT of pollen, because they rely on the wind to carry it to the female cones. Male cones grow on lower branches while female cones are higher in the tree. This reduces self-pollination, as the pollen is more likely to blow up onto another tree, but it also puts a lot of irritating pollen down near your dog. After the male cones release all of their pollen, they fall off the tree. If your dog is allergic to pollen, then May and June will be bad months to let him play around a pine or spruce tree.

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