A fragile-looking plant born from a small, round seed
Who would have thought that it would contain such great natural providence and mystery!

Just as a bird is born from a round egg, it is born from a round seed, takes root in the ground, grows stems and leaves,
92 Amazing, Fun, and Informative Stories About Plants That Bloom and Bear Fruit

One question.
“Plants don’t have bones, so how do they grow straight up?”
This is because animal cells are surrounded by a thin membrane called the 'cell membrane', whereas plant cells are surrounded by a thick, strong partition-like wall called the 'cell wall', and the cell membrane is located inside that wall.

Two questions.
“Why do plants grow their roots downward?”
Plant roots have the property of sensing gravity and growing in that direction, which is called 'positive gravitropism'.
So, if you take the sprout out of the soil and lay it down horizontally in a dark place, the tips of the roots will bend and start growing downwards.


Three questions.
“Why does the morning glory have such a hard shell?”
First, the hard shell helps it withstand heat and cold well, and acts as a protective barrier even in dry environments.
Second, because after the seeds are eaten by animals, they are not digested in the stomach and intestines and must be excreted with the feces.

This book, "The Smart Botany Textbook," contains 92 fascinating, fun, and informative stories that reveal just how fragile-looking plants, born from small, round seeds, hold the great providence and mystery of nature.
By the time you turn the last page of this book, people will be calling you a "lifetime botanist."

As the cell theory reveals, the leaves, stems, roots, and other parts of a plant's body are all made up of cells.
However, plant cells are structurally very different from those of animals, including humans.

Animal cells are surrounded by a thin membrane called the 'cell membrane'.
In comparison, plant cells are surrounded by a thick, strong, partition-like wall called the 'cell wall', and inside that is the cell membrane.
That is, plant cells have a rigid cell wall that animal cells do not have.

The cell wall protects the nucleus and chloroplasts inside the cell, while also supporting the plant body.
The main component of the cell wall is a substance called cellulose.
And as the amount of lignin contained in the cell wall increases, the cell wall becomes stronger.


Plants support their bodies by stacking cells with rigid cell walls.
Thanks to this, plants can stand upright and grow tall even without bones.
---From "1-3 Plants don't have bones, so how do they grow straight up?"

Place the sprouted plants in a box and make a small hole in the side of the box so that only light enters through that hole.
If you look at it a few days later, you will see that the plant stems in the box are growing in a bend toward the light.
So, does that mean that 'the sprouts grow upwards because the sunlight shines down from above'?

The sprout grows upward even in the pitch dark.
Consider bean sprouts grown in boxes that are completely shielded from light.
Bean sprouts grow upward even without light.
The same goes for seeds planted in the soil.
In the soil where light does not penetrate, the sprout pushes the soil and grows upward.

This suggests that the sprout has the ability to distinguish between up and down, regardless of light.
If you take the sprout out of the soil and lay it horizontally while blocking light, you can soon observe the tip of the stem bending upwards and growing.
---From "1-6 Sprouts have the ability to distinguish between up and down?"

When you touch the leaves and stems of a plant, the plant feels a tactile stimulus.
Then, ethylene is produced in the plant body.
As we have already seen, ethylene inhibits the growth of plant stems and makes them plump.
So, when you stroke a plant, ethylene acts to make it grow into a small, hard, and strong plant.
Then the plant will bloom much prettier and more beautiful flowers than usual.
Because plants produce flowers that are as large as they can support.
If you overwhelm the plant with flowers that are too large to handle, the stem will not be able to withstand it and will fall over.

Therefore, plants can produce large, beautiful flowers when their stems are short and plump.
On the other hand, plants that do not feel the touch stimulus grow tall and wiry with thin stems.
These plants produce small flowers that can support themselves.

Plants do not understand kind words and emotions to grow strong and beautiful flowers.
What plants need is physical 'touch', such as proper wind and the gentle touch of humans.
---From "1-9 If you stroke a plant, it will grow strong?"

Plants absorb carbon dioxide through photosynthesis, preventing the concentration of carbon dioxide in the atmosphere from rising.
Can we know specifically how much carbon dioxide plants absorb and contribute to the Earth's environment?

The amount of carbon dioxide absorbed by plants can be seen in the global carbon dioxide concentration curve.
The graph on the right shows the increase in carbon dioxide concentration and is based on data observed in the Northern Hemisphere.
Carbon dioxide concentrations increase or decrease seasonally each year, decreasing in summer and increasing in winter.

Why do carbon dioxide concentrations decrease in summer and increase in winter? In the Northern Hemisphere, plants actively photosynthesize from spring to summer, absorbing large amounts of carbon dioxide, which reduces atmospheric carbon dioxide concentration.
Meanwhile, when cold winters arrive in the Northern Hemisphere, the amount of carbon dioxide absorbed by plants decreases as the rate of photosynthesis decreases, increasing the amount of carbon dioxide in the atmosphere.
By measuring the difference in carbon dioxide concentration, which increases and decreases with the seasons, we can estimate the extent of carbon dioxide absorption by plants.
---From "2-5 Why does carbon dioxide concentration decrease in summer and increase in winter?"

We found that plants measure the length of the night to form buds and bloom.
So, let's move on to the question, 'What part of the plant measures the length of the night?'

To confirm this, an experiment was conducted on morning glory flowers.
As the morning glory sprouted, I kept the lights on to keep it growing.
Morning glory does not form flower buds unless the nights are long.
So, I chose one part each of the leaves, stems, buds, and roots and covered them with something like black paper to partially provide long darkness for flower buds to form.
When the light was blocked in which part of the flower was the flower bud formed?

Flower buds were formed only when the leaves were covered with black paper.
That is, it is the leaves that sense the length of the night required to form flower buds.
For many plants, even the leaves of newly sprouted shoots sense the length of the night.
For example, the cotyledons of morning glory, the first leaves to emerge after the seeds sprout, also sense darkness.
Therefore, if the cotyledons can detect long periods of darkness, it is possible to form flower buds on small shoots.
The leaves of the plant measure the length of darkness required to form flower buds.
That is why leaves that sense darkness are sensitive to light.
---From "3-6 What part of a plant should I block to make flower buds form?"

In 1953, W. of England
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To find out the structure of the opening and closing movement of these flowers, Wood separated the thick petals into two layers, the outer and inner, and floated them on water.
Then, when the water temperature was increased, the inner part of the petals reacted sensitively and grew rapidly.
On the other hand, the outer part of the petals slowly elongated.

The results of this experiment show that 'when the temperature rises, the inner side of the petals grows faster than the outer side, so they spread outward.
It tells us that this is a phenomenon of flowering.

Meanwhile, when the temperature of the water in which the petals were floating was lowered, the inner side of the petals hardly grew, while the outer side grew rapidly.
This means that when the temperature drops, the outer side of the petals grows rapidly, but the inner side hardly grows, so they do not spread outward.
This tells us that 'this is a phenomenon of waste.'
This clearly revealed the opening and closing structure of the flower.

This structure clearly shows that petal elongation is influenced by temperature changes.
This open-close structure, in which the inner side of the petals grows more when the flower opens and the outer side grows more when the flower closes, is a common characteristic of all flowers that open and close.
---From "3-14 How do flower buds open and close?"

Plants with seeds enclosed in hard, thick shells are common around us.
Seeds of morning glory, okra, and spinach are of this type, and are called 'light-bearing seeds'.
To help these seeds germinate quickly, you need to scratch their hard shells or grind them with sandpaper or something similar.
So why do they have such thick shells? What benefits does this provide to the plant?

Seeds have an important role to play in enduring adverse conditions such as heat and cold.
The hard shell helps it withstand heat and cold.
It also acts as a protective barrier in dry environments.

There is another important role of seeds.
It is the act of changing or expanding the plant's growing area.
For this to happen, the seeds must be eaten by the animal and then passed out with the feces without being digested in the stomach and intestines.
Thick shells are also effective in this regard.

Even after taking over a new habitat, the seed still has work to do.
The seed coat also plays an important role in choosing the right time and place for germination.
For seeds to germinate, they need plenty of water to soften their hard shells.
If there is enough water at that time and place, the water needed for sprouting and rooting is guaranteed.
Therefore, the seeds can sprout without worrying about lack of water.

---From "5-9 Why do morning glory seeds have hard shells?"