Little knowledge of deciduous leaves

1. Little knowledge of falling leaves in autumn

Knowledge of autumn leaves 1. Knowledge about fallen leaves

The north of China lies in the north temperate zone. In autumn, due to the low temperature, the rainfall decreases, the absorption of plant roots decreases, and the water and inorganic salts obtained by plants are greatly reduced, so that photosynthesis, respiration and transpiration can not be carried out normally and physiological activities can be obtained. If leaves are left, a lot of water will transpiration, threatening the survival of plants. After cold and drought, new leaves will grow. There are two kinds of fallen leaves: one is that whenever drought or cold season comes,

All the leaves of plants (18) are dead and fall off, leaving only branches, which are deciduous trees, such as peaches. Another: After new leaves appear in spring and summer, the old leaves gradually fall off. As far as the whole tree is concerned, it is evergreen all year round and is an evergreen tree, such as Cinnamomum camphora. Causes of defoliation: Internal cause: After a certain period of physiological activities, a large number of metabolites, such as minerals, accumulate in cells, causing physiological function decline and death (chlorophyll destruction). External factors: the cold weather, lower soil temperature, reduced rainfall, and greatly weakened water absorption capacity of roots. Why do leaves fall off? Why are the leaves so smooth after falling off? ◆ The reason is that some cells (originally calcium pectin, soluble pectin and pectin acid) at or near the base of petiole are produced due to changes in cell or biochemical properties. ◆ The separation zone includes: separation layer and protective layer: cells divide to produce a group of small thin-walled cells. For the separation layer, the cell wall gels and the cells become free. Due to the weak supporting force, combined with the gravity of the leaves and the shaking of the wind, the leaves fall off from the separation layer. Then several layers of cells below the abscission layer are embolized to form a protective layer on the cross section to avoid water loss and invasion of pests and diseases. ◆ Significance of defoliation: It means that plants can reduce transpiration, keep water in their bodies, and survive cold and cold.

Autumn defoliation (8 leaves) is an adaptation to the dry season, which is formed by the long-term evolution of plants. Defoliation mechanism: adapting to bad environment, defoliation can reduce transpiration and make plants spend cold and dry seasons, which is formed by long-term evolution of plants; Short sunshine accelerates delamination formation; The increase of abscisic acid and ethylene can accelerate the shedding of leaves.

2. What are autumn leaves like?

Autumn leaves are like cruise ships, in which frogs swim; Autumn leaves, like animal feathers, fall to the ground and become soft carpets.

1, autumn leaves fall like flying butterflies; Autumn leaves are flying around like a flock of frolicking birds.

2. Autumn leaves fall into the arms of Mother Earth like homesick children; Autumn leaves are like beautiful butterflies, flying all over the sky.

3. Autumn leaves are like fans, covered with golden blankets; Autumn leaves are like postcards sent by autumn girls, sending thoughts of late autumn.

4. The fallen leaves in autumn jump down from the tree like elves in flowered clothes; Autumn leaves are like handfuls of small umbrellas to shelter birds from the wind and rain.

3. Why do leaves fall in autumn

The main purpose of green leaves is to absorb sunlight for photosynthesis, make nutrients and transpiration water. The evaporation of water can prevent trees from being burned by the hot sun. In autumn and winter, the rain is scarce, the air is dry, and the water content in the soil is also reduced, which can not meet the needs of tree growth. At this time, a hormone abscisic acid will be produced in the leaves. When abscisic acid in leaves is transported to the base of petiole, a layer of small parenchyma cells will be formed at the base of petiole, and the cell wall is very thin. The formation of delamination will hinder the normal transport of water to leaves. Under the action of abscisic acid, natural segments will be formed around the abscission layer and the leaves will fall off. Trees falling leaves in autumn can reduce water transpiration, reduce nutrient consumption, and let trees spend the cold and dry winter safely.

-Excerpted from Wang Ying et al. Encyclopedia of Knowledge (2007) 438+0 Why Leaves Fall.

4. Knowledge about fallen leaves

The north of China lies in the north temperate zone. In autumn, due to the low temperature, the rainfall decreases, the absorption of plant roots decreases, and the water and inorganic salts obtained by plants are greatly reduced, so that photosynthesis, respiration and transpiration can not be carried out normally and physiological activities can be obtained.

If leaves are left, a lot of water will transpiration, threatening the survival of plants. After cold and drought, new leaves will grow.

There are two kinds of deciduous trees: one is that when drought or cold season comes, all the leaves (18 leaves) of plants die and fall off, leaving only branches, which are deciduous trees, such as peaches. Another: After new leaves appear in spring and summer, the old leaves gradually fall off. As far as the whole tree is concerned, it is evergreen all year round and is an evergreen tree, such as Cinnamomum camphora.

Causes of defoliation: Internal cause: After a certain period of physiological activities, a large number of metabolites, such as minerals, accumulate in cells, causing physiological function decline and death (chlorophyll destruction). External factors: the cold weather, lower soil temperature, reduced rainfall, and greatly weakened water absorption capacity of roots.

Why do leaves fall off? Why are the leaves so smooth after falling off? ◆ The reason is that some cells (originally calcium pectin, soluble pectin and pectin acid) at or near the base of petiole are produced due to changes in cell or biochemical properties. ◆ The separation zone includes: separation layer and protective layer: cells divide to produce a group of small thin-walled cells. For the separation layer, the cell wall gels and the cells become free. Due to the weak supporting force, combined with the gravity of the leaves and the shaking of the wind, the leaves fall off from the separation layer.

Then several layers of cells below the abscission layer are embolized to form a protective layer on the cross section to avoid water loss and invasion of pests and diseases. The significance of defoliation: it is an adaptation of plants to reduce transpiration, keep water in their bodies, and spend the cold and autumn defoliation (8 leaves) dry season. This habit is formed in the long-term evolution of plants.

Defoliation mechanism: adapting to bad environment, defoliation can reduce transpiration and make plants spend cold and dry seasons, which is formed by long-term evolution of plants; Short sunshine accelerates delamination formation; The increase of abscisic acid and ethylene can accelerate the shedding of leaves.

5. Describe the fallen leaves in autumn

Autumn leaves fall in spring, summer, autumn and winter, and the four seasons alternate.

We have gone through a bright green spring and a colorful summer, and come to this fiery autumn full of * * *. In autumn, fallen leaves are the most striking beauty focus.

The autumn wind swept through the Woods, leaving leaves behind. They dance lightly in the air, like a beautiful butterfly and dancing elves.

Some people say that autumn leaves are withered and worthless. I don't think so.

Autumn leaves are sacred. Although fallen leaves are no longer lovely in spring and vigorous in summer, they are the most valuable dedication of fallen leaves under withering. When the leaves are covered in the spring of March, they begin to absorb sunlight and air, blossom and bear fruit. When the sun is scorching, the leaves join hands to form a huge umbrella, which brings coolness to the birds.

When autumn comes, the withered autumn leaves still decorate the earth with gold and red, showing their final beauty to the world. Autumn wind blows, autumn leaves fall peacefully and openly, blend into the soil, turn into nutrients, and give birth to the hope of spring.

I believe that there will be a faint smile of autumn leaves in the bud next spring. Ah! This is the cycle of life! Ah! Autumn leaves, you are a fairy tale full of affection. You left in a hurry without leaving any dazzling brilliance. You fly gently, regardless of whether you get any praise, but you are so satisfied and serene. This is your character. You absorbed the air and sunshine, and gave birth to flowers all over the sky. The fragrance of melons and fruits is selfless. This is your pursuit. You exhausted your youth and left the last dazzling and golden autumn with your dying body. You openly let the autumn wind take you back to the earth, melt into the soil, turn it into nutrients, and nurture the hope of spring! Autumn leaves, you are the hymn of life. All hearts are baptized because of you. With the autumn sunset, you left in a hurry, leaving no dazzling brilliance. You fly down gently and turn a limited life into eternity. ........................................................................................................................

It was like a golden fairy tale, and I became the only visitor in autumn. In the rustling autumn wind, the dead leaves on the trees have fallen.

It slowly fell to the ground, making a sad "rustling" sound. Falling leaves! Are you mourning the shortness of your life? No, it's not! Leaves will not be so short of breath! Unconsciously, I have reached the end of the road.

I saw a clear stream in front of me, and fallen leaves fell on the stream with the wind, just like a golden boat. The stream kept flowing, and the fallen leaves whirled with the tide, starting their long and arduous journey ... Seeing that there was no way out, I simply lay on the luxurious carpet and looked up. There seems to be some green leaves left on the bare branches.

Maybe in a few days, this green leaf will fall and fall into the arms of Mother Earth. "Fallen leaves are not heartless things, but turn into spring mud to protect flowers.

"yes! It is paying its life for the coming year. Falling leaves! Your glorious life will not end with autumn, because the solid seeds have taken your hope to the next spring.

Falling leaves! You don't have to worry that the bare branches will be frozen by frost, because the tender branches of the past have become ruthless men. Floating leisurely, floating leisurely, and the fallen leaves are still hovering and scattered there.

It doesn't seem to be attached to the branches, and it doesn't worry about fate, just looking for its own home. It believes that since its life has an unusual beginning, it should have an unusual ending.

6. Sentences about autumn leaves

I like the fallen leaves in autumn because they are beautiful. Autumn wind gently blows the leaves, and they fly from one tree to another, as if dancing in flowers. Their colors are yellow, green and semi-yellow. Many leaves fell to the ground. When we step on leaves, it sounds like stepping on a carpet. Our children play games on the leaves, which adds vitality to autumn. Autumn is not only beautiful, but also the season of fruit ripening.

Autumn is coming. In order to make me feel autumn better, my mother found many articles and poems about autumn for me to read. Through reading, I know that autumn in nature is a golden season and also a harvest season.

It should be a cool breeze, flying with all kinds of golden leaves. Falling leaves like butterflies are still flying in the air, just like a golden picture.

But autumn in my hometown is not like this in my eyes. The blue sky in autumn is bluer and higher, and it seems that the sun in autumn is redder and brighter.

After the autumn wind, many trees lost all their leaves, and the ground was covered with golden leaves. After autumn, winter is coming. I picked up a fallen leaf, quietly treasured it and cherished the beauty of autumn! As soon as autumn comes, the fallen leaves begin to fall from the trees. No one will notice this scene, but I can't help but respect the fallen leaves.

In people's eyes, autumn leaves will fall, which is a natural phenomenon. What is there to be afraid of? However, my idea is that fallen leaves are experiencing the most brilliant moment in their lives, because although fallen leaves are their bounden duty, they have been silently dedicating their lives to accompanying trees to shade people, but their thoughts have stopped at a stage. Only at the moment of floating to the root can we truly accept the baptism of life and truly sublimate. No matter people or things, the most brilliant moment in life is this.

I love autumn, not only because it has fallen leaves, drizzle, but also because it has sweet fruits for human beings. I love autumn, because teacher Qiu brushed away the arrogance of the sun with wide sleeves, blocked the cold wind in winter with her body, and gave birth to the hope of spring with sweat.

I love autumn, I love her fallen leaves, her drizzle, her orchard and her fields.

I like autumn. I love autumn flowers because they have amazing power; I love the fields in autumn, because there is the sweat of farmers' uncles; I like the fallen leaves in autumn, because they are a beautiful scenery in autumn.

Autumn wind has started, the harvest season has arrived, autumn is thick, and yellow leaves are falling. In the early morning, the dawn of autumn has come, the sun shines on the earth, and the cool breeze makes us throw all our troubles outside the cloud nine.

Cool breeze, clear water, mountains, blue sky, faint smoke, dense forests, yellow leaves, Levin and white clouds, autumn scenery is so beautiful that it is full of praise. Autumn is a picturesque poem.

Autumn is a chapter in life. When the leaves fall in autumn, my face has lost its former brilliance, and the mid-term exam is over. This autumn, I got nothing.

Last autumn, I gained the satisfaction and joy brought by the exam. Fallen leaves look like butterflies in my eyes. It's so beautiful. When the leaves fall in autumn, they stop dancing, but fall sadly, so desolate.

The hope sown in spring has now turned into disappointment. Autumn wind has hit, cold and diligent, and loss is playing in the ear with the roar of autumn wind. The farmer's simple smile is so dazzling at the moment, and the poet's melancholy is so close at the moment.

The last sunset lingers in the western sky, and the bleak autumn wind urges down the fallen leaves of two rows of buttonwood trees on the road from the art museum to the boys' dormitory in Cangcheng High School. Thick fallen leaves accumulated the chill of the whole autumn.

Mo Huaiyuan shivered and stepped on the fallen leaves. Perhaps, whose thoughts is this fallen leaf accumulation? Mo Huaiyuan thinks so.

He felt hungry, so he walked out of the school gate, found a stall in a streetcar as dim as running water in Ma Rulong, and ate a big bowl of wonton at random. I haven't eaten wonton for a long time, have I? Mo Huaiyuan remembers that it was last autumn. He only knew Liu Sifeng for a month, but because of the same hunger, he went to eat wonton together.

In autumn, fallen leaves support me. I love autumn, because the fallen leaves always block the cold for me with their own bodies. Let me not be cold, autumn is warm, that is dedication and comfort.

In this way, I spent another ninety days in warmth. In autumn, I play with my friends in the street while my parents are away.

Although it was autumn, I still had a good time, sweating profusely, and I sat there to rest. Coincidentally, I met that aunt again. Aunt is wearing short sleeves, a pair of leggings and a pair of cloth shoes, and she is still concentrating on sweeping the floor.

I saw her walking under a big tree, and the fallen leaves fell slowly and leisurely. My aunt swept the fallen leaves carefully. Although this is not her job, she is not careless. After a dustpan has been swept, it seems that the fallen baby doesn't understand the cleaner's mind and still leaves his mother's arms, but the cleaner's aunt is not discouraged or upset and still sweeps.

I saw it, and my heart shook badly. In autumn, the colors of leaves change and fall off one by one. The fallen leaves on the path are red carpets and colorful.

Stepping on the fallen leaves, there is a crisp sound under your feet, like a sweet poem. What beautiful autumn leaves! Autumn is a beautiful season; Autumn is the season when melons and fruits are fragrant and harvest joy; Autumn is a season full of childlike interest; Children can catch crickets and pick fruits, fly kites in golden fields and pick up fallen leaves in the Woods. When the collected leaves are put together into patterns, they will be the most beautiful pictures in the world.

The weather in autumn is getting colder, and pieces of yellow leaves, like beautiful yellow butterflies, leave the warm embrace of mother tree one after another and gently float down from the tree and land on the grass, rivers and crops. This fallen leaf seems to be a messenger, telling everyone that "autumn is coming, autumn is coming".

The grass also took off its green clothes and put on its golden autumn clothes. Miss Qiu returned to the world with the joy of falling leaves.

In this scene that can be seen everywhere in Huang Chengcheng, all kinds of flowers seem to be asleep. They all bow their heads, and their two long-tarnished "hands" silently.

7. What are autumn leaves like?

1, autumn leaves fall like butterflies dancing in white; Autumn leaves fly around like flocks of frolicking birds; Autumn leaves are like a thick blanket, wrapping the earth.

The fallen leaves in autumn are flat, like a mountain with three sharp corners. Some are curly and wrinkled, just like grandma's shriveled hands. The colors of fallen leaves are even more strange, like the green and yellow-green cheese that just fell.

After falling for a long time, the knife is covered with layers of dust, and some leaves even turn light brown. Compared with the leaves on the tree, the gap is really too big. Touch the fallen leaves in autumn, which are uneven and even a little stinging!

4. Some are like maple leaves in the palm of a baby's hand, some are like chestnut leaves returned by a saw, and some are like ginkgo leaves of a fan ... Their colors are colorful, and ginkgo leaves turn into handfuls of small yellow fans, and maple leaves turn into red "Jinpu fans".

8. Autumn leaves

[autumn leaves]

People often say: "A year's plan lies in spring and autumn." I can also say this: "The beauty of a year lies in autumn."

Autumn is beautiful, and autumn leaves are more beautiful. I love autumn, and I love autumn leaves more.

I like walking on the path where autumn leaves fly best, which is the most charming place in autumn. At the end of the path is a quiet grove. Walking into the forest, I saw all kinds of fallen leaves covered with a thick carpet. Maybe Uncle Qiu is preparing for the coming of winter. Autumn leaves written by primary school students. A gust of autumn wind swept away, and a large area of fallen leaves fell one after another, dancing like butterflies, spreading their wings like orioles, and spinning lightly like dancers in the air.

Look, there are some leaves floating over there. The leaves are as golden as the sunset, and the golden color is mixed with faint orange, as if the afterglow of the sunset dyed the whole grove red. Facing the flying leaves, I quickly reached out and caught one. Ah, what beautiful autumn leaves! Gently, thin, wearing colorful floral clothes, in the sunset, still glowing with golden light!

As soon as I turned around, another peach leaf fell beside me. I bent down to pick it up and held it in my hand to study it carefully. What a special autumn leaf! It hasn't come yet, it has completely faded, and it still exudes a strong aroma.

I can't help spinning in the autumn leaves hovering in the wind. I shouted excitedly: "I love you-autumn leaves." There was also a happy echo in the Woods. ...

[Autumn Leaves] Essay: What is failure? Nothing, just a step closer to success; What is success? That is, after all the roads leading to failure, there is only one road left, and that is the road to success.