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Pinecones!

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.

Pinecone

Seed scale!

A Characteristic of Pinecones

Pinecones
Can Open and Close

Repeatedly

Pinecones open and close depending on the weather
Scientists found that the weather change triggers the reversible transformation of the pinecone. Under cold and wet weather, seed scales of a pinecone are closed up to protect and bear the seed. On the contrary, when the weather is warm and dry, the pinecone opens up the structure and exposes the seed scales.

 

"Why do pinecones keep opening and closing following the weather changes?"

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Pinecones are waiting the perfect weather condition for the seed dispersion

The seed is packaged inside of the scale for effective seed dispersion. These seed scales in a pinecone start their journey when the enough force of the wind detaches them from the pinecone.

At this time, warm and dry weather conditions 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. Pinecones may open and expose the seed scales in the day of warm and dry to take full advantage of this. 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.

Humidity decides not tree

A fun fact is the pine tree does nothing special when it comes to opening and closing pinecones. And because this task is programmed to the pine tree's preferred climatic conditions, it can achieve its goal with little effort at the moment it desires.

"

“The scales of pinecones 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.”

from https://www.futurity.org/pine-cone-shading-system-1844342-2/

"

If you look closely at the cross-section picture below, you can see that the pinecone opens as the scales bend.

It adjusts the degree of opening by varying the degree of deflection. So it can be repeatedly opened and closed.
Interestingly, changes in ambient humidity cause this warpage.

"What does this discovery mean for us?"

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Click and Read
Pinecone's Opening Mechanism

Image:

The cones of conifers are closed when dry (left) and open by themselves when wet.

Image © C. Zollfrank, Technical University of Munich

Learning from Pinecones

Steel Awning on Modern House

@ thermostat system

Pinecone
gave inspiratio
ns

 

Energy efficient shading system for thermostat

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.

Image:

Prototype of coupled bilayered planks. Image ©ETH Zurich

Image:

Adaptive shading system. Image ©ETH Zurich

Buildings consume 40% of energy!

Up to 40%
    Energy Savings!

     Thank you

 pinecones!

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.

Exploration

You can build a hygrometer utilizing the opening and closing principle of pinecones.
Follow the instruction, and try to create a pinecone hygrometer. Check the humidity level of your room.

Discovering the Pinecones

Click and discover pinecones

Introduction

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Let's collect pinecones from around!

Let's find the pinecones from a neighborhood and observe how they mobilize their seed scales. Is it real that pinecones can respond to humidity changes?

Let's collect pinecones from around!

Are there pine trees in your area?

Collect Pinecones                 in Neighborhood!

Screenshot 2023-01-12 at 3.12.53 PM.png

Image:

from GBIF.org (2020), GBIF Home Page. Available from: https://www.gbif.org [13 January 2020].

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 seed scales. Is it real that pinecones can respond to humidity changes?

Meet different pinecones among the coniferous tree family!

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Pine

cedar.jpg

Cedar

spruce.jpg

Spruce

cypress.jpg

Cypress

Click and learn about this plant

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Redcedar

fir.png

Fir

larch.jpg

Larch

hemlock.jpg

Hemlock

Making Pinecone Hygrometer

Click and see how to make it

Introduction

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Difficulty: Easy
Time taken: 10-20min
Components:

  • pinecone

  • water tray with water

  • graph paper

  • aluminum foil

  • thin pin

  • PET bottle or PET cup

  • marker

  • glue

  • thermo-hygrometer (optional)

Step1: Cut a plastic bottle to make a pinecone hygrometer

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Cut a plastic bottle.

It will become the body of the hygrometer.

Step2: Soak a pinecone in water

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Soak a pinecone in water to close the scales.

Step3: Insert a thin pin to the pinecone

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Lightly insert a needle into the tip of the prepared wet pinecone in the direction the scale is facing.

Step4: Fix the pinecone to the bottom of the bottle with glue.

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Fix the pinecone to the bottom of the bottle

Step5: Attach a graph paper to the body of the hygrometer

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Cut and attach a graph paper to the body of the hygrometer.

 

Mark the initial height of the needle with a marker on the graph paper.

Step6: Record and compare the needle height that changes as the pinecone opens

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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

Close the window, pinecones!

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. 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 quite common with coniferous trees.

However, even in the same coniferous tree family, there are distinctive trees have novel strategies. Some 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, or 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.

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?

"

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!

"

Pinweed

In response to humidity, the coils behind the seeds can be uncoiled. This rotational force is used for drilling and planting in the ground.

Create inventions!

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Click and learn about this plant

Reference and Further Readings

  • Dawson, C., Vincent, J. F., & Rocca, A. M. (1997). How pine cones open. Nature , 390(6661), 668-668.

  • Vailati, C., Bachtiar, E., Hass, P., Burgert, I., & Rüggeberg, M. (2018). An autonomous shading system based on coupled wood bilayer elements. Energy and Buildings, 158, 1013-1022.ISO 690.

  • Quan, H., Pirosa, A., Yang, W., Ritchie, R. O., & Meyers, M. A. (2021). Hydration-induced reversible deformation of the pine cone. Acta Biomaterialia, 128, 370-383.ISO 690.

  • Poppinga, S., Zollfrank, C., Prucker, O., Rühe, J., Menges, A., Cheng, T., & Speck, T. (2018). Toward a new generation of smart biomimetic actuators for architecture. Advanced Materials , 30(19), 1703653.

  • Vailati, C., Hass, P., Burgert, I., & Rüggeberg, M. (2017). Upscaling of wood bilayers: design principles for controlling shape change and increasing moisture change rate. Materials and Structures, 50(6), 1-12.

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