Unlocking the Secrets of the Pinecone
Depending on where you live, this time of year the ground might be covered in snow, ice, and most importantly – pinecones! We see pinecones everywhere during the winter, in wreaths, on trees, and in our yards, but did you know that pinecones have a vital job – they keep pine tree seeds safe, and protect them from the freezing temperatures during the winter!
To protect their precious seeds, pinecones can close their ‘scales’ tightly, keeping out cold temperatures, winds, ice, and even animals that might eat the seeds.
In this activity we will observe how pinecones respond to different temperatures, by mimicking changes in weather, all from the safety of our own kitchens! As an added bonus, after this activity your pinecones will be ready to be added to your house as a holiday decoration, or as a beautiful reminder of the plants of the season!
Did you know that pinecones can stay on pine trees for over ten years before falling to the ground?! During that time, seeds for new pine trees grow under the scales of the pinecones. The scales protect the seeds from bad weather, and from animals that might eat them. However, eventually the seeds need to be released so that they can grow into new pine trees. To make sure that the seeds have the best chance of finding fertile soil and growing into trees, the pinecone scales stay tightly closed when the weather is inhospitable to new seed growth, i.e. when it’s very cold and damp outside. In contrast, when the weather is hot and dry, the seeds will have an easier time finding good soil and growing into trees. In these conditions, the pinecone scales will open, allowing seeds to escape and drift away, to find new ground to grow into new trees!
As you will observe today, after pinecones fall from the tree, they can still open and close. In this activity, we will test the conditions that cause pinecones to open and close, all from the warmth of our own home!
- Pinecones (at least 3)
- An oven
- A large clear glass jar or bowl, large enough to hold ~2 cups of water
- A measuring tape
- Cold water (adding ice to the water will make the effect more dramatic)
- A timer
- Tin foil
- A piece of paper and pencil/pen
- A baking tray
- A spoon or fork
- Permanent marker
- An adult helper
- With the help of an adult, preheat the oven to 250 degrees
- Cover your baking tray with tinfoil
- Fill up the glass jar with cold water (including a few pieces of ice if available)
- Use your permanent marker to label your pinecones. On the first one write the letter “A”. On the second pinecone write “B” and on the third, write “C”.
- On your paper, make 3 rows. Label the rows “A”, “B” and “C”. Draw 6 columns. Label the columns “Initial Length”, “Initial Circumference”, “Cold Water Length”, “Cold Water Circumference”, “Final Length”, “Final Circumference”.
*For all measurements in this activity, use centimeters (cm)
- Use your measuring tape to measure the length of each each pinecone. For each pinecone, write down the length in the column “Initial Length”.
- Use your measuring tape to measure the circumference of each pinecone at the widest point. For each pinecone, write down the circumference in the column “Initial Circumference”.
- Place pinecone A in the cold water. Use your spoon to hold the pinecone under the water. Keep it there for 2 minutes. What do you notice about the pinecone in the water? Does it sink or float? Why do you think this is true? Do you notice any changes as the pinecone sits in the cold water?
- Remove the pinecone from the cold water.
- Use your measuring tape to measure the length of pinecone A. Write down the length in the column “Cold Water Length”.
- Use your measuring tape to measure the circumference of pinecone A at the widest point. For each pinecone, write down the circumference in the column “Cold Water Circumference”. Compare the length and circumference of pinecone A in each column. Did the length or circumference of the pinecone change after you put it in cold water? If so, what kind of changes did you notice? Did it get larger or smaller? Do you notice any other changes about the pinecone? Does it look different? In what way?
- Place pinecone A and pinecone B on the baking tray. With the help of an adult, put the tray in the 250 degree oven.
- With the help of an adult, check the pinecones every 10 minutes to make sure they don’t burn. Are the pinecones changing in any way as they get warmer? What do you notice about them as they get hot?
- After 45 minutes and with the help of an adult, remove the pinecones from the oven. Allow them to cool until you can handle them comfortably.
- Use your measuring tape to measure the length of pinecone A, B, and C at the widest point. For each pinecone, write down the circumference in the column “Final Length”.
- Use your measuring tape to measure the circumference of pinecone A, B, and C at the widest point. For each pinecone, write down the circumference in the column “Final Circumference”.
- Compare the length and circumference of the pinecones for each column. If you like, you can use math to measure the changes using a few simple equations: (use the same equations to look for changes in length, by substituting length for circumference)
Initial Circumference Pinecone A
– Coldwater Circumference Pinecone A
Change caused by cold water for Pinecone A
Final Circumference Pinecone A
– Coldwater Circumference Pinecone A
Change caused by hot oven for Pinecone A
Final Circumference Pinecone B
– Initial Circumference Pinecone B
Change caused by hot oven for Pinecone B
Final Circumference Pinecone C
– Initial Circumference Pinecone C
Change caused by control conditions (air) for Pinecone C
- Using the data collected, determine which pinecone had the biggest change from the initial length and circumference. Notice which pinecone had the smallest change. Why do you think some pinecones changed more/less than other pinecones? Do you notice any other changes about the pinecones? Do they look different? In what way?
Extra: After taking them out of the oven, try putting the pinecones back into the cold water. Remove them after several minutes and measure their length and circumference again. How does cold water affect the size and shape of the pinecones?
Extra: Try lowering the temperature of the oven to 150 degrees, and testing the effect on the size and shape of the pinecone. Do the pinecones get larger than they did in the 250 degree oven, or smaller? Why do you think this happens?
Extra: After taking the pinecones out of the oven and measuring, put them in the freezer overnight. When you take them out in the morning, measure the length and circumference again, and compare them to the final measurements. Did the pinecones get larger or smaller? What other changes do you observe?
Observations and Results
In the activity you observed and recorded the affect of different temperature and conditions on the size and appearance of pinecones. In the first part of the activity, you may have noticed that placing pinecone A in the cold water caused the circumference of the pinecone to decrease. This is the expected result. In response to cold and damp conditions, pinecone scales close tightly, making a natural shell to protect the precious seeds inside.
After taking pinecone A and B out of the oven, you measured all of the pinecones to get their final measurements. When you compared the final measurement of pinecone A to the cold water measurements, you should have observed that the circumference of pinecone A increased after being in the hot oven. In addition, when you compared the final measurements to the initial measurements for all the pinecones, you may have noticed that the circumference of pinecones A and B both increased. In each case, the increase in the circumference of the pinecones results from the scales of the pinecones opening up in response to the warmth of the oven. The pinecones think it’s a warm summer day, and are ready to release their seeds!