top of page

Eye on Nature

Habitats

Industrial Uses

Inspiring Yourself

Learn from Biomimicry Design Cases

Rain
Check,
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.

Pine Cone

Seed scale!

A Design Idea inside 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?

a83d10b2-f32a-4aa1-a258-f16ac04704c8_edited.jpg

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.

Literally, a seed scale is the carrier of a pine tree seed. That's why the seed scales look like a bird's wing to glide far away. Many tree plants, including maple trees, have also taken this idea for the seed dispersion.

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 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.”

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.

In other words, 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.

What does this discovery mean for us?

Learning from Pinecones

Steel Awning on Modern House

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 seed 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!

"

“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.”

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

"

Exploration

Let's collect pine cones from around!

Are there pine trees in your area?

Screenshot 2023-01-12 at 3.12.53 PM.png

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?

Collect pinecones                 in Neighborhood!

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

Meet different pinecones among the coniferous tree family!

pine.jpg

Pine

cedar.jpg

Cedar

spruce.jpg

Spruce

cypress.jpg

Cypress

Click and learn about this plant

fir.png

Fir

redcedar.jpg

Redcedar

larch.jpg

Larch

hemlock.jpg

Hemlock

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:

  • pinecone

  • water tray with water

  • graph paper

  • aluminum foil

  • thin pin

  • PET bottle or PET cup

  • marker

  • glue

  • 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

Attach a thin pin to the pine cone

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

Rain check, 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.

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.

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?

"

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!

"

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.

7.CalPhotos_0000_0000_0209_0996.jpg
7_edited.jpg
913.103404.jpg
913_edited.jpg
84.CalPhotos_4444_4444_0811_0722.jpg
84_edited.jpg
509.49288728.jpg
509_edited.jpg
537.0f38953f1d25799ac97470541fd5ec61.jpg
537_edited.jpg

Click and learn about this plant

Reference and Further Readings

  • Faber, J. A., Arrieta, A. F., & Studart, A. R. (2018). Bioinspired spring origami. Science, 359(6382), 1386-1391.

  • 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.

  • ETH Zürich and Purdue University image

  • https://archive.iii.kyushu-u.ac.jp/public/KelYAAdJowFA-u0B4G1z0EI2dL9S5lQeFw8FwRkmLxlm (Last Access Nov. 30, 2022)

bottom of page