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Pinecones!
Scales of a pinecone
The pinecone reminds the holiday season with its spiral and scrubby outfits, a perfect ornament for a Christmas tree decoration. The beauty of this nature-based ornament comes from the kaleidoscopic 3D geometry. The spiral arrangement of woody seed scales constructs multi-layers, delivering different experiences from various viewpoints. But just a few know that the pinecone can close and open its multi-layered structure in response to environmental humidity changes.
Design inside Pinecones
Pinecones
Bend Seed Scales
to Open the Structure
Pinecones
Bend Seed Scales
to Open the Structure
The change of weather triggers the shape transition
When the pinecone folds the scales, it turns into an armored egg. It conceals all individual scales and becomes hard to break. However, when the pinecone raises a blockade, the hidden scales are exposed again and show its flaky structure.
Notably, this morphological transition is reversible so that the pinecone can redo the blockage repeatedly.
Scientists found that the weather change triggers this reversible transformation of the pinecone. Under cold and wet weather, pinecone scales are closed up to protect and bear the scales. On the contrary, when the weather is warm and dry, the pinecone opens up the structure and exposes the scales.
Then why do the pinecones make this transformation following the weather changes?
The weather condition is critical for the seed dispersion
The secret of the pinecone is hidden in the scale. Actually, the scale is the carrier of the pine tree seed.
The seed is packaged inside of the scale for both protection and effective seed dispersion. If you observe the individual scales closely, you'll know directly that the scales look like a bird's wing. Definitely, it is an excellent strategy to disperse the seed for a long distance. The wing-shaped scale increases the flight distance when enough force from the wind launches it. And many tree plants, including maple trees, have also taken this idea for seeding.
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So the answer on the previous question "Why are the weather changes important for the pinecone?" The answer is seeding.
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D-day is a warm and dry day
The good strategy to increase the survival rates of the pinecones are spreading them as wide as possible. Warm and dry weather conditions may give advantages in spreading the seeds far distances. Because there is more chance to avoid rain and experience streamlined wind flow which can carry the seed to far distances. This might be an excellent strategy to avoid unnecessary competition among the seedlings in a restricted small area and find more favorable places to grow.
So it can be understood that pine trees have evolved to avoid wet and rainy days for successful seed dispersal. At rainy days, the pinecone is closed to keep the seeds from being dispersed. And when the weather is dry and windy, the cones open and release the seeds carried away by the wind.
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Bending makes opening
Take a good look at the picture below. Can you imagine how a pinecone will open and close?
Meet the Pinecone
Are there pine trees in your area?
Pinecones are small, cone-shaped fruits containing conifers' seeds, such as pine trees. It is fertilized via pollen to produce seeds during the spring season. After that, trees form pinecones to safely grow seeds until those are mature and no longer need protection. In particular, heavy rain, wind, or hot sunlight over the summer season can damage the seeds, so this must be avoided. For the reason that securely passes the harmful season, pinecones stay closed to protect the seeds inside and ensure that the seeds grow safely.
Let's find the pinecones from a neighborhood and observe how they mobilize their scales. Is it real that pinecones can respond to humidity changes?
Collect pinecones in Neighborhood!
from GBIF.org (2020), GBIF Home Page. Available from: https://www.gbif.org [13 January 2020].
Meet different shapes of cones among the coniferous tree families!
Pine
Cedar
Spruce
Cypress
Click and learn about this plant
Fir
Redcedar
Larch
Hemlock
Learning from Pinecones
Meet the Pine Trees
Pinecone
gave inspirations @
Energy efficient shading system
Why shading system?
A building exposed to direct sunlight in midsummer is sweltering. On days like this, we use blinds to block direct sunlight and turn on the air conditioner to lower the room temperature.
According to the International Energy Agency, buildings are the world's largest energy consumer, accounting for more than 40% of energy consumption. Unfortunately, people rely on electricity-powered thermostat systems to help control the room temperature. That's why buildings use most of their energy for heating and cooling.
To save our planet, some engineers have focused on the problem and started to design a shading control thermostat system that consumes much less electrical energy.
Pinecone inspired shading control system
This pinecone-inspired shading system reacts on its own according to weather changes. Unlike conventional blinds, these do not require sensors, motors, or electrical energy.
As we know, a pinecone moves in response to changes in humidity. For example, when humidity decreases, it causes the bending of the scales, and the pinecone is simultaneously closed and, in dry weather vice versa. Engineers got an idea from this phenomenon and brought this opening and closing system to the blind.
The panels of the blinds are layered with different types of wood, and the fibers are also oriented vertically. Like a pinecone, the blinds move according to the humidity changes. And it adjusts the amount of light entering the room. These blinds can be placed on the roof of a building or a window on a building facade.
Opening and Closing Mechanism of Pinecones
How do pinecones open?
The scales of a pinecone are actually made up of two layers. One of the layers has more holes (porous structure) in the surface than the other layer. Therefore, these two layers have a difference in expansion rate according to humidity. When the day is wet, in high moisture, the outer layer of the pinecone scales expands longer than the inner layer. So the scales bend inward and the pinecone closes. Conversely, when dry, the outer layer shrinks shorter than the inner layer. This causes the scales to bend outward and open the pinecone. What's even more interesting is that the pine tree does not use any external electrical energy to open and close the pine cones. It's very eco-friendly!
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“The scales of pine cones react to changes in humidity. For example, if the humidity decreases, the scales bend and move from a straight to a curved shape—so the cone opens in dry weather. It is the cone’s structure that makes this possible because the scales consist of two connected layers that contract to different degrees as the humidity decreases.”
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from https://www.futurity.org/pine-cone-shading-system-1844342-2/
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Exploration
You can build a hygrometer utilizing the opening and closing principle of pinecones. Follow the instruction, and try to create a pinecone hygrometer. And check the humidity level of your room.
Making Pinecone Hygrometer
Click and see how to make it
Introduction
Difficulty: Easy
Time taken: 10-20min
Components:
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pinecone
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water tray with water
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graph paper
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aluminum foil
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thin pin
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PET bottle or PET cup
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marker
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glue
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thermo-hygrometer (optional)
Step1: Soak a Pinecone in Water
Soak a pinecone in water to close the scales
Step2: Cut a plastic bottle to make a pinecone hygrometer
Cut a plastic bottle. It will become the body of the hygrometer
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Attach a thin pin to the pine cone
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Attach graph paper to the body of the hygrometer
Step3: Cut a plastic bottle to make a pinecone hygrometer
Observe the change of the pinecone while drying
Check the height of the thin pin that changes while opening the pinecone. Record the height on the graph paper
Expand Your Vision
Various logics to gain the upper hand in reproduction
As we have seen above, the reason the pinecone opens at the right moment is to achieve successful reproduction of the species.
Many plants aim for good seed dispersion time to gain the upper hand in reproduction. If you ask what the 'good time' for the seed dispersion is, the answer would be a little tricky because the decision-making logic may differ from the plant species.
The pine tree launches seed dispersion when the day is warm and dry. They prefer warm and windy day to disperse the seeds scales with enough force from the wind. It might help the pine trees to reproduce. This characteristic is known as in common with all coniferous trees.
But, some other pinecones do not open in usually warm and dry weather, unlike what we've seen above. These pinecones open and release seeds in extreme conditions such as wildfires, extreme heat, and drought. These unique traits can expect an explosive spread in extreme conditions like wildfires, where competitors are eliminated, and seedlings can grow in empty, fertile ground.
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These cases are breaking down our stereotypes about plants.
It is interesting to note that even plants that seem to live passively can actively perceive and respond to changes in their surroundings.
Let's investigate active plants that can act in response to specific conditions, such as pinecones.
What plants can act in response to environmental changes like pinecones?
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Plants can move?
Surprisingly, many plants can move in response to certain conditions or energies. It's just that we don't feel it because the movement is too slow or not much dynamic for our timeline. Listed here are the series of plants that can move in response to certain conditions. Check out how these plants can move!
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Codariocalyx
Move in the direction of the sun. Because of the growth-stimulating hormone called auxin, the auxin accumulates on the opposite side of the light, and makes that part grows faster.
Click and learn about this plant
Let's Make it Real
Rain check, pinecones!
We raised this design problem before we start the journey to the secret of the folding-pattern of earwig wings.
Finally, it's the time to design and invent a model satellite!
Did you get any mind brushing ideas from the earwig? There would be millions of solutions.
Before we start to do design and invention, let's make quick answers for the following questions!
Question 1: How wide were the wings when they are folded and unfolded?
Question 2: How can we apply the folding of earwigs’ wings to artificial satellites?
What are the advantages?
Question 3: What fields and products can we apply the method of folding the wings of earwigs?
Expand your imagination like an earwig!!~
Reference and Further Readings
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Faber, J. A., Arrieta, A. F., & Studart, A. R. (2018). Bioinspired spring origami. Science, 359(6382), 1386-1391.
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Saito, K., Pérez-De La Fuente, R., Arimoto, K., Seong, Y. A., Aonuma, H., Niiyama, R., & You, Z. (2020). Earwig fan designing: Biomimetic and evolutionary biology applications. Proceedings of the National Academy of Sciences, 117(30), 17622-17626.
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ETH Zürich and Purdue University image
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https://archive.iii.kyushu-u.ac.jp/public/KelYAAdJowFA-u0B4G1z0EI2dL9S5lQeFw8FwRkmLxlm (Last Access Nov. 30, 2022)