How leaves appear on trees in spring for schoolchildren. Spring: First leaves on the trees

Autumn leaf fall

Autumn leaf fall is an unusually bright and amazing natural phenomenon that amazes with beauty. Looking at the golden leaves flying around, which are spreading with soft carpets, the question certainly arises: how does this process work and why, in fact, do the leaves fall in autumn?

Many tree species are shedding their leaves to survive adverse weather conditions. In the tropics and subtropics, the leaves fall off at the beginning of the dry season; in temperate regions, trees shed their leaves in the fall when cold weather approaches. Trees that shed their leaves at certain times of the year are known as deciduous trees. Trees whose leaves do not fall are called evergreen trees.

Most species of deciduous trees have broad leaves that fall off in cold or dry weather. Evergreen trees, unlike deciduous trees, grow in humid, warm climates or have weather-resistant needles.

Interesting fact: Evergreen trees retain their leaves throughout the year because their foliage is waxed to keep out the cold, and their cells contain anti-freeze chemicals that keep the tree from freezing in low ambient temperatures. Deciduous trees, on the other hand, are very susceptible to cold.

Evergreen trees retain their foliage throughout the year

Reasons for leaf fall:

• daylight hours;
• leaf damage;
• arid climate;
• cold climate;
• tree pollination.

day length

Destruction of chlorophyll in the leaf with a reduction in daylight hours

In autumn, daylight hours gradually decrease. As exposure to daylight decreases, the production of chlorophyll, the green pigment that the plant uses to absorb sunlight and then convert it into nutrients, decreases; and the process of photosynthesis (which is carried out with the participation of chlorophyll) slows down until it stops.

Interesting:

Why is there so much water when roasting chicken?

As a result, the production of sucrose, which plants use as food, stops, and, consequently, the supply of nutrients to the tree is limited. To reduce the need for nutrients and withstand cold or drought, trees shed their leaves.

Interesting fact: It is noticed that forest trees shed their leaves faster than urban ones. This is due to the fact that the city has more lighting, including artificial (lanterns, light from windows, cars, etc.).

Leaf damage

By the end of summer, the leaves are damaged by insects, disease, or general wear and tear and are ready to be renewed. With the arrival of autumn, the trees are faced with low ambient temperatures, cold winds and other conditions that also damage the leaves. For these reasons, the leaves fall off. In addition, in addition to nutrients, harmful substances (metabolites, excess mineral salts) are collected in the leaves. Therefore, getting rid of the leaves, the plant is cleansed.

arid climate

Deciduous trees shed their foliage during dry spells to avoid desiccation

In hot weather, the leaves evaporate a lot of moisture. The roots of the tree, supplying the leaves, lose a large amount of water. Coniferous foliage, so-called. evergreen trees do not fall off, since their needles, occupying a small surface area, require less moisture compared to deciduous trees. Thus, deciduous trees shed their leaves during the dry season to reduce their need for moisture and avoid desiccation.

cold climate

In autumn, trees, feeling the reduction of daylight and the decrease in air temperature, begin to prepare for the cold. To conserve sufficient water and energy resources for winter period, plants accumulate nutrients and get rid of leaves. This process occurs cyclically and does not harm the plant. This is how autumn leaves fall.

Interesting:

Why are there red buses and telephone booths in London?

Accumulation of nutrients

Trees collect valuable nutrients (nutrients) from the leaves and store them in the roots for further use. Chlorophyll (the pigment that turns leaves green) is the first to break down into nutrients. By the way, in connection with this, the leaves change color in autumn from green to orange, crimson, gold.

Separating the leaves from the tree

A separating layer of cells separates the leaf from the branch, resulting in the process of leaf fall.

Leaves are sheared from the tree with a sheath that forms at the point where the stem of the leaf joins the branch, and is a collection of cells. As autumn days are reduced, this layer clogs the vessels on the stem of the leaf, which move water into the leaf, and nutrients into the tree. After the stem is clogged, the layer becomes dry and scaly and, as a result of decomposition, separates the leaf from the tree. In the spring, new stems appear in place of fallen leaves and leaves grow.

Trees, getting rid of the leaves, enter into a state of suspended animation, which is compared to deep sleep. At this time, the plant uses the nutrient reserves deposited in the summer.

Benefits of fallen leaves

Fallen leaves continue to benefit trees

Fallen leaves do not lose ecological significance. When decomposing them useful material flock to the soil and feed future generations of plant and animal life. Thanks to this, the tree receives the necessary nutrients to grow new leaves. In addition, a layer of discarded leaves covering the soil warms the tree and protects it from freezing in the cold season.

Despite the apparent chaos and disorder, in most plants the leaves are arranged on the stems and branches so correctly that it is possible to establish their location. general rules.

On superficial observation, it seems that most often the leaves are arranged without any order, that they are scattered, as is said and still is in most of the descriptive writings (folia sparsa). Only in those plants in which each stem node bears more than one leaf, the correct leaf arrangement is striking and has long been noticed. If the leaves sit in pairs and one against the other, then it is rightly expressed about them that they are opposite, or opposite (folia opposita).

At the same time, it almost always happens that leaf pairs alternate with each other - then the leaves of the nearest pairs fall on each other crosswise, the leaves of the third pair, counting from below, fall directly above the leaves of the first pair, the leaves of the 4th pair are above the leaves of the 2nd, etc. To indicate this circumstance, the expression cross-seated (ff decussata) is used. This happens, for example, with our maples, lilacs, and all labiales (mint, sage, etc.). Instead of two leaves, there are 3 leaves on one node, for example. in the oleander, and then the nearest leaves of such triple rings or circles also alternate with each other; such plants are also known that have 4, 6, 10, and even more leaves on each node (many madder, Hippuris, etc.).

But even in these cases, the leaves of the nearest circles alternate. Such leaves can be called ringed, or ringed (f. f. verticillata). Paired and opposite, obviously, belong here, only the number of leaves in their circles is brought to the smallest. If on stems with ringed leaves we mentally connect all the leaves sitting on top of each other, we get several vertical and parallel lines, which are called orthostiches. The number of such orthostychus will obviously be twice the number of leaves in a given circle. The correctness resulting from this is so clear that, for example, in plants with opposite leaves, especially if there are many leaves, their four orthostiches are visible at first glance. Scattered leaves represent another kind of correctness. Stems and branches with such leaves produce one leaf at each node.

If we start from any leaf, eg. from the lowest, we mentally draw a line to the nearest sheet, and from the second again to the nearest, etc. to the end, then this line will turn out to be helical, and on a horizontal projection it will be spiral. Therefore, the L. itself is called spiral, the leaves - spirally arranged (f. f. spiraliter posita).

This turns out to be the following. Going in a spiral, for example. up from this sheet, we reach the one that is above the first (from which we started). In some plants, like the linden, this leaf is always the 3rd, the 4th is above the 2nd, the 5th above the 3rd, etc.; in others, like the alder, the 4th is above the 1st, the 5th is above the 2nd, etc.; the third, for example. in aspen, above the 1st there is the 6th, above the 2nd - the 7th, etc. If you draw vertical lines through all mutually covering leaves, then their number will be equal to the number of leaves located between two mutually covering leaves: 2nd for linden, 3rd for alder, 5 for aspen.

If we measure the horizontal distance between the orthostiches, then it will be constant for each plant and will be equal to the segment of the spiral connecting 2 mutually covering leaves. This segment is called the full cycle of leaf arrangement. In some plants (linden, alder) it makes one revolution around the stem, in others (aspen, poplar, apple tree) it makes 2 revolutions, in others (Carduus) - 3 revolutions, etc. This distance is measured by an arc and the corresponding angle , between the two nearest leaves is called the divergence (divergentia) of the leaves, and the angle measuring the magnitude of the divergence is called the divergence angle (angulus divergentiae).

It is clear that this angle depends on the number of revolutions in a complete cycle and on the number of leaves located along the line of a complete cycle. If there is one turn, i.e. one circle, and there are 2 leaves in the cycle, then to find the angle of divergence, you need to divide the circle in two, you get the angle of divergence in 1/2, where 1 means the number of revolutions in the cycle, and 2 is the number of leaves; if the number of leaves is 3, then the circle is divided by 3, a discrepancy of 1/3 is obtained, if the number of revolutions is 2 (i.e., 2 circles), and there are 5 leaves, then these 2 circles should obviously be divided by 5, a discrepancy will be obtained 2/5, where 2 again means the number of revolutions, and 5 is the number of leaves of the cycle.

Examining many plants, it was found that in nature there are very different discrepancies, but most often the following come across in nature: 1/2, 1/3, 2/5, 3/8, 5/13, 8/21, etc. , but of these, the first three are the most common. Each of these fractions, meaning a discrepancy, at the same time, obviously, also means the L. itself, indicating in the denominator the number of leaves in the cycle and the number of vertical rows (orthostich) formed by them, and in the numerator - the number of revolutions of the spiral in a full cycle .

Therefore, each leaf arrangement can be denoted by the number of leaf rows, or orthosts: they are called two-row (1/2), three-row (1/3), etc. In nature, however, except for those divergences that are indicated in the above series of fractions, called the main thing, since it comes across much more often than others, there are other rows, for example. 1/3, 1/4, 2/7, etc. or 1/4, 1/5, 2/9, etc. In all these series of discrepancies, it is noticed that each subsequent fraction is obtained by adding the numerators and denominators of the previous two, which, however, does not indicate any legitimacy in the very nature of plants.

For a visual representation of L., it is convenient to represent them on a horizontal projection obtained by mentally drawing vertical lines from the points of attachment of leaves with the leafy stem itself in a vertical position. The intersection points of the verticals (perpendiculars) with the horizontal plane will obviously be located in the same way as the leaves are located on the stem. Instead of dots, arcs are usually drawn, meaning leaves (their cross section), thickening the arcs in those places where dots were obtained on the projection, i.e., in the middle of each arc. Such a drawing is a plan of a leafy shoot, since a circle is drawn in the middle of it, meaning a cross section of the stem itself. This plan is a diagram of a leaf-bearing shoot. The diagrams clearly show the number of leaves of the cycle, their mutual arrangement and the angle of divergence.

They are used most of all in the study of inflorescences and flowers. The correct arrangement of the leaves, although observed in most plants, but exceptions are known, that is, such plants in which the discrepancy is not constant. In addition, the divergence often changes during the transition from the main stem to the branches, which, however, always takes place in the same way. It should also be noted that in many plants the rows of mutually overlapping leaves, although they remain parallel, do not appear to be vertical, but curved. In every polynomial L., one can always open, in addition to that main helix, or spiral, which passes through all the leaves of the shoot, secondary, steeper spirals heading in 2 opposite directions.

These minor spirals are called parastiches. Parastychs of one direction, taken together, apparently also capture all the leaves of the shoot, but each of them only a known part of them, namely 1/2 of all leaves, if there are 2 parastiches of the same name, one third - if there are three of them, etc., which already follows from the fact that they are parallel and capture all the leaves of the shoot. If the main spiral is very shallow and unnoticeable, as is the case on shoots with very numerous L., then parastihi are used to open the main spiral. To do this, you need to renumber all the leaves on the parastihi of both directions, starting from any, observing that there is a difference between the numbers equal to the number of parastikha.

After renumbering all the parastiches, the main spiral turns out to be by itself. The correctness in the arrangement of leaves, discovered and depicted using the above method, is in the closest connection with the development and internal structure of plants, it also corresponds to the need for adaptation of plants to environmental conditions, but a physiological explanation has not yet been found here.

The studies of Negeli, Hofmeister, and Schwendener showed that in many cases, L. at the beginning of shoot development, when the leaves look like small tubercles, is different than at the end of development. The last of these scientists also showed that, due to the slower growth of the shoot bearing leaves compared to the growth of the leaves themselves, the leaves undergo mutual pressure, shift in certain directions and change their position, finally settling down according to a well-known formula only at the end of their development.

These investigations, while still explaining the previously noticed difference between the arrangement of leaves at the beginning and at the end, do not, however, give a complete mechanical explanation, since in many cases, for example, on shoots with opposite leaves, these leaves are located from the very beginning in the same way as they are located at the end. Science owes most of all to Alexander Brown, Schimper, and the Bravais brothers for the fundamental study and very formulation of L..

Literature. A. Braun, "Vergleichende Untersuchung ueber die Ordnung der Schuppen an der Tannenzapfen" ("Abhandlungen der Leopoldinisch-Karolinischen Akademie", vol. 14); L. F. et A. Bravais, "Essai sur la disposition des feuilles curvis érie es" ("An. d. sc. nat.", 1837, vol. 7); they, "Essai sur la disposition des feuilles rectis érié es" ("An. des sc. nat.", 1838); C. Schimper, "Ueber die M öeglichkeit eines Wissenschaftlichen Verstä ndnisses der Blatt-Stellung, mitgetheilt von A. Braun" ("Flora", 1835, nos. 10, 11 and 12); Simon Schwendener, "Mechanische Theorie der Blattstellungen" (Lpts., 1878).

In this article, we have collected material on the topic "tree leaves" and "tree structure". Acquaintance with the tree begins for the child in his earliest childhood.

Each yard has its own good-natured giant, who will gladly shelter from the scorching sun, rain, share fallen leaves and dry twigs for all kinds. However, many children perceive trees as nameless satellites, not thinking about the fact that each of them has its own name, has a complex structure and performs important tasks. Therefore, with a deeper study of trees, kids make many discoveries for themselves.

For example, children will be interested to know what parts a tree consists of. To do this, we use a schematic image of a tree and talk about each part of it:

1. The roots of a tree are its foundation. They feed the tree by absorbing the nutrients dissolved in the water, and also keep it upright. The larger the tree, the richer its root system.
2. The trunk of a tree is, as it were, its body. All the substances extracted by the roots pass up the trunk, while branches begin to depart from the trunk. It is important to note that a real tree has one trunk, but shrubs have several, even large, trunks.
3. Tree branches - support for leaves; it is on the branches that buds are formed, from which leaves and flowers then appear. Nutrients also pass through them. Over time, the branches become wider and harder (woody), and new branches appear from them.
4. The foliage of a tree is an organ that allows the tree to exchange substances with the environment. Thanks to the leaves, the tree absorbs carbon dioxide harmful to humans from the air, here, under the action of sunlight, carbon dioxide is formed from it. organic matter, and through the leaves, the tree releases the oxygen we breathe out.
5. All the leaves and branches of the tree form its crown - a lush hat that gives shade and shelters us from the rain.

Having studied the structure of a tree, you can proceed to the next stage - to find out how it comes into being. Where and how do trees grow? The answer to this question can be represented in the form of a circular diagram.

So, we analyze the whole life cycle fruit tree:

A seed is the source of life for every plant, including a tree. It contains a small germ and the initial supply of nutrients that the germ needs in order to germinate through the seed coat. Once in the soil, the embryo begins to actively develop, pecks through the shell, grows and puts out roots, with which it absorbs the substances necessary for its growth from the ground.

After many years, the embryo turns into a tree, which, having reached a certain age, acquires the ability to reproduce its own kind.

In spring, buds form on the branches of a tree, in which an organ of amazing beauty and smell develops - a flower.

The flower of a fruit tree is arranged in such a way that when pollinated (by wind or insects), a small rudiment of the fruit is formed in it.

The beginning of its development and rapid growth occurs in the spring, when buds are actively formed on the branches, from which leaves and flowers subsequently appear. No wonder it is said that in spring the trees come to life after a winter sleep.

In summer, the trees appear before us in all their glory. They constantly interact with the outside world, feed, replenish the reserves of substances necessary for their life. The leaves of the trees are constantly working in the summer, turning into a real factory for processing carbon dioxide, and producing oxygen and nutrients from it.

All vital processes in the tree are on the decline: daylight hours become shorter, and the amount of sunlight is not enough to form new chlorophyll molecules in the leaves, so the foliage gradually changes its color and falls off. Leaf fall not only saves the tree's strength, which it will need to survive the harsh winter, but also saves tree branches from breaking off, which can occur under the weight of the fallen snow.

The tree seems to freeze. It economically spends the reserves accumulated over the summer and is looking forward to the arrival of the first spring warmth.

But not all trees go through such a cycle of transformations, but only those that have leaves, that is, deciduous ones. But the trees, whose branches are covered with needles - needles (coniferous) all winter look the same as in summer.

The most famous coniferous tree is. Of course, it became famous thanks to the Russian tradition of decorating spruce branches on New Year's Eve. Spruce reproduces with the help of cones that form during the summer.

But of the deciduous trees, the most common are:

• - a tree with bright berries and beautiful jagged foliage, which looks especially impressive in autumn. There is a version that it was called mountain ash because its leaves are quite small and, when the wind blows, they tremble, causing ripples in the eyes of the one who looks at it.

• Birch is a symbol of Russia, a unique tree with white bark. Its very name comes from a Slavic word meaning "shine, turn white." The birch is also interesting for its flowers, which look like earrings, and the fact that its branches are very long and thin, they seem to hang down.

• Poplar is a frequent companion of human habitation. Poplars are planted near houses because they grow quickly - which means they start to purify the air early and absorb well excess moisture. In the wild, poplar is often found in wetlands, for which it got its name, which in translation from Slavic means "marshy place, swamp." Poplar fruits are boxes from which seeds are spilled, covered with many silky hairs - poplar fluff. This fluff gives people a lot of inconvenience, so poplars are often cut off, leaving only non-fruitful branches at the top.

• Oak - a tree - a giant, especially revered by our ancestors. Its fruits - acorns - were used to make a drink that replaces coffee, but oak bark and wood, which is distinguished by its strength and beautiful color, have found even greater use among people.

• Maple - the owner beautiful leaves with sharp edges. A sweet aromatic maple syrup is obtained from its juice.

• Elm is a tree, wood, branches and bark of which people have used for the manufacture of furniture, tools and even weapons since ancient times. Elm bark (bast) is strong and flexible, various objects were tied to it, for which the tree got its name. Shoes were woven from bast.

• Chestnut is a tree with unusual fruits, the core of which resembles a nut. It is believed that the word "chestnut" has the same root with the word "porridge", since chestnut fruits were often eaten.

• Willow is a tree with unusual long branches and narrow leaves. Its name comes from the word "twist", which is explained by the main use of willow branches - baskets were woven from them, furniture was woven.

In order to better remember the names of the trees, you can play a simple game: shuffle the cards with the image of the leaves and the trees themselves, and then match them and name them.

From the leaves you can make a very interesting visual aid for children. To do this, you need to collect leaves different types and laminate them.

Cut out the leaves slightly stepping back from the edge.

We get a living manual for the study of leaf types.

Print on a separate piece of paper the names of the trees from where you collected the leaves. The name of the tree is compared with the leaf itself, studying and memorizing its shape and structural features.

Images of leaves are more visible in coloring pages, where you can see their contour and give color depending on the expected season and shades characteristic of a particular tree.

birch coloring page

Hello, friends!
Today we are waiting for a new issue of the biological finger theater with a question from why Arina and Katerina Lazarev, who was sent by their mother Tatyana, author of the blog "Together with Mom". The girls have already come to the rubric, and today we will deal with the botanical issue: Why do flowers appear on trees first and then leaves?

The elephant is already ringing the bell.

Chapter 1

Elephant: I declare a new representation of BioTOP open.
kaffir raven: BioTOP! Biotope! Hearing the case of pollination.
meerkat: We will fight the dust? I have just the right tail. If you rub it with a plastic comb and fluff it, dust easily collects on it. Like iron to a magnet.
Elephant: We will deal with the matter of dust another time. And now we will talk about pollen and its transfer from flower to flower.
meerkat (grumbled): Then the name "pollination" is inaccurate, it should have been called "pollination".

Dragonfly(rolls her eyes dreamily): How opportune that we will deal with pollination today! After all, my candidate, a great specialist in this problem, is flying to us. And what a glamorous pink color he has!
Galapagos Albatross: Not the tiny hummingbirds you're talking about, Dragonfly?
Dragonfly: Sometimes they are called "northern hummingbirds". But these are not birds.

A pink bullet flashed through the air. Something whistled past Owl's ear.
Owl(goggling eyes): Fathers! Shoot! Get down!
Everyone lay down in the grass, peering ahead. Nothing happened. But then an unfamiliar voice came from behind.
Voice: And what's in there? Are you looking for something interesting?
The mudskipper jumped in surprise. And the Elephant slowly turned back, her eyes converged to the bridge of her nose. There was a small bright pink spot in front of the trunk.

Dragonfly: Meet! This is my deputy! Hawk hawk.
Hawk hawk: Wine hawk. At your service!
Owl: Well, you have chosen a candidate for yourself, Dragonfly! Moth hawk - that's what the people call a drunkard. Not only is a drunkard, but also wine!
Kaffir Raven: Where was your head, Dragonfly, when we invited a candidate with bad habits to our team?
Elephant: What do you say in your defense, Wine hawk?

wine hawk(sang piercingly):

THE SONG OF THE WINE HAWK
(

I'm called the wine hawk,
But I only swear to you
What about deep drunkards,
As a class I do not belong!

I'm indifferent to braga
There is no truth in wine!
No cravings for beer
Alcohol is not for me.

I feed on nectar
Among the night flowers -
Their fragrant charms
Ready to surrender.

On vine leaves
I start life.
In honor of these wine berries,
Call me my friends!

Once a greedy clerk,
Suddenly regretted the ink:
He is the name "grape"
Reduced to "wine".

Fell victim to the bureaucrat
My noble family
Let's say guys
Boycott in vain!



Kaffir Raven: Wow, what a harmful clerk got caught!
Dragonfly: You see! He was slandered. The wine hawker is not a drunkard at all. He is the largest specialist in antecology!
mudskipper Q: What kind of science is this? Antenna?
orangutan: If my memory serves me, this is the science of flowering and pollination. After all, "anthos" is translated from Latin as "flower".
Wine hawker: Quite right, dear Orangutan!
Octopus: Then, you will definitely be able to say why trees first have leaves, and then flowers.

Chapter 2

Orangutan: I always wondered how the flowers manage to grow ahead of the leaves? After all, in order for flowers to appear, sugar must accumulate. And sugar, just, the leaves produce.
wine hawk: Flowering before leaves is obtained in those plants that have a supply of sugar.It takes a lot of sugar to produce pollen.In trees, such a reserve is in the branches.At a birch, for example.
meerkat(licking): Is that why birch sap is so sweet?
wine hawk: Absolutely right! In winter, the leaves of the trees fall. But before that, they give the branches all the sugar they have produced. Trees stand with bare branches, tall. They bloom in the spring when there are no or very few pollinators. Trees do not count on their help, but turn to the wind as a carrier of pollen. Therefore, the flowers of spring trees are very economical - odorless and nectar, small and inconspicuous, collected in earrings.

meerkat (mentally, hanging the birch with earrings): Something I did not notice on the birch earrings.
orangutan (noticing the expression on the face of the Meerkat): Earrings are not Jewelry, but inflorescences that sway in the wind near birch, poplar, alder, aspen, hazel.
wine hawk: Yes, they are a bit like fluffy caterpillars.
orangutan (quickly glancing at another expression on the squeamish face of the Meerkat): Our Meerkat has a very vivid imagination.
Owl: You, Wine hawk, would have been better off showing the Meerkat what these catkin inflorescences of yours really look like. And then, he imagined caterpillars in earrings.
meerkat(looked suspiciously at Owl): Here and there. Earrings separately - caterpillars separately.
wine hawk(smiling): We can see such earrings only in spring, but I have photos.

The wine hawk showed photos of the inflorescence of the catkin.

Meerkat: Indeed, caterpillars! I have a riddle! Remember last time we learned

MYSTERY ABOUT INFLOWERING EARRING
(

On the birch: oh-oh-oh!
Who hung upside down?
These are caterpillars in a row,
Bent legs,
And swing, hang,
Scattering crumbs.

Dragonfly Q: Why do they have such a similar shape?
Wine hawker: It is very convenient for the pollen to spill out at the slightest breeze. After all, pollination in spring trees with catkins most often occurs with air currents.

Orangutan: Plants that are pollinated by the wind are called anemophilous.
Owl: Well, what kind of anthropoid are you! Simply put, wind pollinated plants.
Dragonfly: But, you are all talking about pollen. Does this mean that all the flowers in the earring are boys? After all, pollen is male cells.
wine hawk: Your assumption is correct, dear Dragonfly. Earrings are a convenient form for male inflorescences. And there is a lot of pollen in them.
Owl: You won't understand these trees. As soon as the snow melts, they are already blooming. Wait until it warms up.
wine hawk: But when it gets warmer, leaves will appear.
Owl: So what? Let them appear. What do they interfere with?
wine hawk Q: Let's do an experiment! Then we'll find out.

Chapter 3

Materials: Dark paper, white gouache or white corrector, adhesive tape, scissors, a plate of flour, tree branches, paper leaves, clothespins.

Attention! Experiment outside, or in the bathroom, as there will be flour everywhere.

1. On dark paper, draw white outlines of birch trees. Pay attention to the shape of the branches hanging down. Such branches sway better in the wind. Make two copies.
2. On the branches of birches, stick pieces of adhesive tape, sticky side up. You can use double-sided tape, or roll one-sided into a ring. These pieces of adhesive tape will symbolize female birch flowers with pistils on which pollen should fall. Let's put one of the copies vertically, leaning against a support.
3 . Insert tree branches into clothespins or press down with a pebble. We put them at a distance of 50 cm in front of the picture with adhesive tape. These are our trees from which pollen will fly.

4. Put 1 teaspoon of flour on a plate. Flour will be our pollen. Let's bring the plate to the trees and forcefully blow on the flour, causing it to scatter in the direction of the painted grove.
5. Consider tape. Has flour stuck to it? How dusty is the background?
6. Cut out leaves from paper and use tape to attach them to the branches.

7. Let's replace the background grove with the second instance. Let's repeat the experiment with flour.
8. Compare results. And draw your own conclusions.

meerkat: Wow! Leaves interfere with pollination!
wine hawk: Right! You need to spend tens of times more pollen for pollination to occur. And there is not enough sugar for that.
orangutan: Those flowers that had time to open before the leaves appeared were more likely to produce seeds. Therefore, the trees bloom before the leaves appear.
meerkat: And now I understand why birches grow in whole groves! To make pollination easier.
Wine hawker: Wonderful observation! Well done! Wind pollinated plants grow in groups. And the pollen from the earrings begins to crumble at a certain time. For example, in the morning. This improves pollination efficiency and conserves pollen.
Dragonfly: And snowdrops are in a hurry to bloom until the leaves appear on the trees?
Wine hawker: That's right, dear Dragonfly. Snowdrops in the forest bloom as long as the light falls under the trees. Leaves will appear, create a shadow.
Octopus: But the wind blows wherever it pleases. Will self-pollination occur? After all, the seeds then turn out to be weak, unable to germinate?

Chapter 4

Orangutan:Self-pollination is an undesirable thing for a plant. Although there are some plants that self-pollinate normally. For example, peas. Another hoof. Self-pollination is a necessary measure.
wine hawk: Plants have found interesting solutions to prevent self-pollination. They divided bisexual flowers into male and female.
meerkat: What is it like?
Wine hawker:

ABOUT MALE AND FEMALE FLOWERS
(

If a flower, people
There are pistil and stamens
He will be bisexual
Please take this into account!

If there are only stamens,
At the head - dust grains of dust.
We have such a flower
It's called male.

If the pistil is lonely -
We call the flower feminine.

orangutan: Moreover, to prevent self-pollination, the flowers are separated by time. Male flowers on the tree bloom a little earlier than female ones.

wine hawk: Right! Or the flowers are separated by space. For example, female flowers grow on one tree, and male flowers on another. Like poplar, willow, nettle, date palm.

meerkat: Ah... So that's why my potted palm doesn't give dates! She can't pollinate.
Wine hawker: On date palm plantations, female plants are even grafted with twigs with male flowers.
mudskipper: That would be appreciated by the Angler! After all, people did what deep-sea anglers do. They have a small male, sticks to a huge female, and they grow together so as not to look for each other in the dark. So a man grafts a small twig of a male palm tree onto a huge female one.
Meerkat: This is how I need to do it! To grow a branch on my palm tree. Does the wind also pollinate the palm tree?
wine hawk: Wind, wind.

Owl: There is something wrong with you! I have seen more than once how bees and bumblebees collected pollen from spring trees! And you say that the wind pollinates them! Lies! Bees pollinate them!

Wine hawker: Dear Owl, the main thing for plants is that pollen gets on the pistil, and how this happens is a secondary issue. Often plants combine several methods. And let's, in order to resolve our dispute, we will ask the bee itself.

Chapter 5

Owl: Dear bee! Can I have you for a minute!

Bee: Hello!

Owl: I saw how you take pollen from trees in spring. So, bees partially pollinate birch, poplar, aspen?

Bee: I think no. They have some strange pollen. Small, smooth, dry. No taste in it, no aroma. Dust particles slide off us, and do not stick. What a difference, dandelion pollen! Large, fragrant. It sticks easily into balls. You will fill full baskets with legs with it, and you will also bring it to the hive on a body.

Owl: But willow then, do you pollinate?

Bee: We pollinate the willow. She has tasty and sticky pollen. She sticks to us well.

Owl: Then why do you collect dry and tasteless pollen?

Bee: So, we take it, because there is nothing else. That's when the willow blooms, we switch to it. And so - on bezrybe and poplar fish.
Orangutan: In the spring, even starving spiders eat pollen that has fallen into the network.
Mud Jumper: Why do you need pollen, Bee? Don't bees collect nectar for honey?
Bee: We also take pollen. From pollen we make bread for children - perga. Without such bread, they will die.Most best flowers those that have nectar and pollen! They are noticeable from afar both in appearance and aroma. They give both honey and perga for the bees.

mudskipper (speaking to the orangutan): And what are these flowers called correctly?

orangutan:Entomophilous.

Owl: And in a simple way - insect infested.

Bee: I have no time to chat with you! I flew.

Chapter 6

The bee flew away, and from somewhere in the grass a voice was heard:

mudskipper (bouncing): Oh, talking wire!

SONG OF THE DODDLE
(

I consider the leaves to be a flaw,
I hate green.
And I won't be photosynthesising
I get myself lunch!

I am not a green peasant.
Stronghold of the aristocracy!
Let me in the hot sun
The green rabble is working!

I'm proud of my roots
They rise above the earth
And become a thin princess
Outshine the plants!

Orangutan:Dear Dodder, I'm afraid you have no place in our clearing.

Elephant: Care to explain your words, Orangutan? Why are you oppressing the lady?

Dodder(squirming): I protest! I will complain! Give me a complaint book!

Albatross flew away with Dodder in its beak.

Elephant: Here is the insidious person Dodder! But, Kaffir Raven, write down a valuable thought. We should start a book of complaints and suggestions. We must not be separated from the people!

Wine hawker: Have you tried mango? Now, if you strengthen its specific bad smell, you get the smell of bats. After all, mangoes are pollinated by flying dogs, and they also distribute the fruits.
meerkat (rolling eyes thoughtfully): Flying dogs....
Owl(looking at Meerkat's face): Bat dogs are big bats.
meerkat: Dogs?
Owl (waving a wing at Meerkat): It will be necessary to pay attention to the mango. Mouse is good.
mudskipper: What are the names of flowers pollinated by bats?
orangutan: Chiropterophilic.
Owl: You will break your tongue. Chiroptero...

Wine hawker: In the 18th century, there lived a talented scientist Erasmus Darwin, who wrote an amazing botanical poem "The Love of Flowers", it is just about the secrets of flowers and their pollination.
Owl: Is he a relative of the same Darwin who wrote about evolution?
Wine hawker: Erasmus Darwin is his grandfather. And I have in store, written in his style.
The wine hawker began to recite poetry, but not everyone understood high poetry. And the Meerkat listened to the images with such an expression on his face that the Elephant was worried about his vivid imagination. As soon as the poems ended, Meerkat rushed off to look at the pollen of flowers under a microscope, hoping to see ships and horses in it.

Owl: Now try to separate the knights from the pollen for the Meerkat.
Dragonfly: How much we learned today that everything is messed up!

Kaffir Raven: No problem! I wrote everything down! I know how to sort out all the signs of pollination of flowers. Let's play one very interesting game "POLLINATION".
Elephant: Let's play! Let's play! I declare the show closed!

Botanical game "POLLINATION"

Rules of the game: The game is designed for 2-5 players. It is possible to increase the number of players by duplicating fields with signs of pollination.

1. Print out the fields. If necessary, print the fields with characteristics.
2 . Glue three cubes with signs for pollination in flowers. Or glue the names of the features on the edge of a plastic or wood cube.
3 . Distribute one board with the traits per player: "Wind Pollination", "Water Pollination", "Insect Pollination", "Bird Pollination", "Bat Pollination".
4. Throw three dice at the same time, and if the sign on the edge matches the sign on the player's field, the cell next to it is closed with a flower chip.
5 . The player's task is to collect all the signs for the plant as quickly as possible.
PS: On the "wind pollinated" field, to equalize the chances, you need to collect only 5 signs out of 7.

DOWNLOAD THE GAME "POllination" FROM THE BLOG "MAGIC OF BIOLOGY" FOR FREE.

Here is another question solved in the BioTOP finger biological theater. Arina and Katya, I present the second certificate of honorary whys. Many thanks to Tatyana for the active support of the rubric. If you have any questions, please write them to the mail, or in the comments.

If you liked it, tell your friends about the Biology Magic blog. This is the best thank you for me. Let there be more people who are not indifferent to wildlife.

The tree that opens the flowering season is alder. Its inflorescences are inconspicuous, but nevertheless, during the period of mass flowering, they will certainly attract attention if we pass somewhere along the bank of a stream or near a ravine at this time, where alders are usually found. Even from a distance you can see the reddish tint of the tree crown. Coming closer, we will see a large number of drooping earrings, which, with the slightest tapping on the trunk or a breath of wind, will throw out whole clouds of yellow dust. In addition to these earrings, we will also find numerous black knobs on the alder. While the catkins are the male alder buds, these buds are last year's female buds that are still hanging on the tree and fall off only by early summer.

Almost simultaneously with alder in early spring, when snow drifts still lie in the depths of the forest, hazel, or hazel, a common and well-known shrub in our forests, blooms on the edge, on the slopes baked by the sun. However, hazel is popular only in autumn, when its fruits ripen; in the spring no one pays attention to him, especially when he stands in a leafless state. Meanwhile, just at this time, he is perhaps the most interesting in a biological sense. Hazel blossom is taken by some phenologists as the beginning of the third period of spring, which at this time finally comes into its own.

First flowering shrub
Almost simultaneously with alder in early spring, when snowdrifts still lie in the depths of the forest, hazel, or hazel, a common and well-known shrub in our forests, blooms on the edge, on the sun-baked slopes. However, hazel is popular only in autumn, when its fruits ripen; in the spring no one pays attention to him, especially when he stands in a leafless state. Meanwhile, just at this time, he is perhaps the most interesting in a biological sense. Hazel blossom is taken by some phenologists as the beginning of the third period of spring, which at this time finally comes into its own. At this time, warm sunny days are usually already set, the snow melts quickly and awakening flora every day becomes more and more noticeable. If the birch and maple, with the beginning of their sap flow, seemed to catch the first glimpses of the coming spring, then the modest flowers of the hazel mark its complete reversal, the final victory over winter.

Early flowering of hazel, as well as alder, is possible only thanks to the advance preparation of its inflorescences. Throughout the winter, on its branches, we observe male earrings, in which there are fully formed flowers. They endure thirty-degree frosts, but as soon as they begin their development, they already become much more sensitive to lower temperatures and during the flowering period they often suffer from frost. The structure of male hazel earrings at first glance resembles the already familiar alder earrings.

The development of a flower earring in spring occurs with exceptional speed. As soon as the sun warms up and the temperature rises, the earrings begin to crack, and the stem on which the flowers sit stretches and grows almost before our eyes. So, for example, on a cut branch of a hazel in a humid chamber, the stem of a male earring elongated by as much as 3 cm in a day. The rate of anther cracking is closely dependent on the degree of air humidity. In a humid atmosphere, the opening of the anthers is delayed for several days, but if the earring is moved to a dry place, it occurs in half an hour. This circumstance is of great importance in the life of the plant. It allows him, as it were, to wait out rainy weather and postpone flowering until a more favorable time. However, in rainy weather, the already opened gaps of the anthers have the ability to close again. It also significantly reduces waste of pollen. The amount of pollen released by hazel trees during the flowering period is enormous. One earring of it gives about 4 million pollen grains, and if we assume that there will be at least a hundred such earrings on an average bush, but in fact much more, then one can imagine what a colossal amount of tiny dust particles is carried in spring in the air in our forests. Let us now turn to the female hazel flowers. Unlike males, they are hidden in the kidney in winter and become noticeable only in spring, when purple tassels of stigmas appear from the scales.

Does the intense red color of the stigmas have any biological significance? Many have probably paid attention to the fact that young leaves developing from buds in spring, or sprouts of herbaceous perennials, are bright red in color. It is clearly visible on large sprouts of horse sorrel or on young leaves of maple, cherry or oak. This red color is due to the presence in plant tissues of a special pigment - anthocyanin, dissolved in cell sap. We will dwell on it in more detail in the chapter on leaf fall, and now we will point out that anthocyanin is currently attributed the role of an additional trap from the wind. By absorbing the green and blue rays of the spectrum, it contributes to an increase in the temperature in the cells, which is of great importance in the cool spring time. It is believed that the intense pink color of the stigmas of hazel, as well as the purple color of the female alder inflorescences, thus accelerates the germination of pollen on the stigmas, which occurs more vigorously under conditions of elevated temperature.

When buds are laid at the hazel
Deployment of leaves in hazel occurs much later than its flowering. Only after the male earrings have dusted off, darken, dry up and begin to fall off the branches, the buds begin to bloom, covering the shrub with a delicate green haze. Why do leaf buds open much later than female flower buds or male catkins? Why is the development of our shrub proceeding with such a regular sequence, first opening its huge flowers, and then dressing in its green attire? It can be assumed that in hazel, as in most of our other trees and shrubs that bloom before leafing out, the development of flower and the development of vegetative buds are different stages, the onset of which requires different temperature conditions. The deployment of vegetative buds requires much more heat than the development of flower buds. Hazel buds, having begun their development, subsequently bloom extremely quickly, since all the necessary parts have been laid in them since the previous year. This bud formation takes place much earlier than is usually imagined, and already in the middle of summer, in most of our trees and shrubs, fully formed buds can always be found on young shoots. So, for example, on May 25, buds consisting of 6-10 scales were observed on young growing shoots of hazel. On June 10, there were already 12-14 scales on these buds, but leaf primordia were not yet noticeable among them. They appeared in the buds in early July, first in the amount of one or two, and by August 11 the next 2-3 leaves had developed.

It is remarkable that already at that time in the axils of these tiny leaves, under strong magnification, small buds of two to four scales could be found. These bud primordia must therefore overwinter twice before they begin their development. This is how long the hazel buds go through before they become noticeable or we pay attention to them!

What are kidney scales
In most plants, for example, in willow, hawthorn, wild rose, etc., in adult leaves, we can distinguish three main parts - the leaf blade, which serves for light nutrition of plants, the petiole, which supports the leaf blade and attaches it to the stem, and, finally, stipules. Stipules usually look like two small leaves located at the base of the leaf petiole, and their purpose is not always clear at first glance. However, the significant role that they play in plant life becomes clear in the spring, when the buds on the trees begin to develop. It turns out that in hazel, as in most of our trees and shrubs, the bud scales, which play such a significant role in the life of plants in winter, are nothing more than stipules, which in the bud significantly outstrip the corresponding leaves in their development. At the hazel, the stipules fall off, having fulfilled their purpose, immediately after the shoot develops, and in the summer it is no longer possible to find them on the shoots. In linden, this fall of stipules at the time of leafing out is so noticeable that in linden forests in spring all the soil under the trees is strewn with pinkish or slightly greenish bud scales. In other trees, stipules persist throughout the life of the plant. They turn green and take part in assimilation. However, one should not think that in all our trees and shrubs the kidney scales are formed by stipules. The currant is completely devoid of stipules, and in its buds the scales are expanded leaf petioles. In horse chestnut, bud scales are modified leaf blades. This is not difficult to verify at the moment of blooming of its large buds, where you can easily observe all the transitions between bud scales and real leaves. We now know what the bud scales of the hazel are. Let's see how they are arranged. There is one interesting detail here. If we make a transverse section through the kidney scale and look at it under a microscope, we will find a special cavity inside. This cavity is filled with air, which is known to be a very poor conductor of heat. As a result, the protective role of scales increases, which protect delicate leaf primordia from sudden temperature fluctuations.

After the shoot of the hazel finishes its development - flowering, deployment of growth buds, growth of shoots and the laying of new buds, we will not notice further significant changes. Nevertheless, important processes of seed maturation in fertilized ovaries and the deposition of reserve substances in leaf buds and flower male catkins take place in summer, which ensures their development next spring.

Seed ripening in hazel is extremely slow. Despite the fact that this shrub blooms extremely early, its fruits fully ripen only by September. In this it differs sharply from our other trees and shrubs, the fruiting period of which is much shorter. It is especially curious that the period of fruit ripening in willow and aspen usually does not exceed a month, while in hazel it averages four months. It is difficult to say what these features of the fruiting of various plants are connected with, however, in the future we will partially return to this issue.

Our willows in early spring
In early spring, among our wind-pollinated trees and shrubs, hung with modest, nondescript catkins, flowering willow bushes attract attention from afar. At this time, against the gray, still transparent background of the forest, bright yellow willow inflorescences stand out sharply, densely covered with sticky pollen and emitting a delicate and pleasant aroma. However, long before flowering, many willows, especially red willow, become quite noticeable due to their graceful fluffy inflorescences, known as "lambs". The sudden appearance of these "lambs" in the middle of winter, in January or February, is one of the most curious phenomena in the life of our spring nature. However, before getting acquainted with the vital characteristics of willows, it should be noted that we have a large number of species. In total, in the flora of the USSR, there are currently about 170 species of willows, and in the Moscow region alone, their number reaches 40. With such a variety of species, willows have the ability to give hybrids with each other, and often double and triple. At present, even five and six hybrids are known, which are extremely difficult to understand. We will have in mind only some of the most famous and common willows among those that bloom in early spring before the leaves bloom. This includes the well-known red willow, or red willow (Salix purpurea), common in the south of the European part of the USSR, reaching in the north to the southern border of the Moscow region and introduced into culture; goat willow, or bred willow (Salix caprea), ubiquitous in forests, and ash willow (S. cinerea), growing in damp places in most of the USSR. Other willows that are widespread in our country, such as the white willow (Salix alba) or the brittle willow (Salix fragilis), growing along the banks of ponds and near dwellings in the form of large weeping trees, bloom much later, simultaneously with the development of young leaves.

When willow flower buds awaken from their winter sleep
The dormant period of our early willows lasts until mid-January. Until this time, their kidneys are densely scaled and do not show any noticeable changes. However, starting from the end of January, flower buds begin to show undoubted signs of incipient development. The caps crack at the very base and, not being able to embrace the swelling flower earring, gradually move towards its top or to the side, and then completely fall off. However, this process proceeds at an extremely slow pace and usually ends completely only by the second half of March.

The dropping of caps in our early willows is an extremely interesting phenomenon. In February, there are the lowest temperatures, twenty-degree frosts often crack and the soil freezes to the maximum depth. Nevertheless, the swelling of flower catkins undoubtedly indicates the beginning of the development of plants, their exit from winter stupor. The life of our trees in winter has not yet been studied enough, but there is reason to believe that during periods of thaw and on warm sunny days in separate branches and sap flow begins. In them, the transformation of spare substances takes place and they move to the kidneys from various parts of the crown and trunk.

Let us now follow further the development of flower catkins in the willow. Having thrown off their caps, they look like elegant, fluffy white balls, similar from a distance to small tufts of cotton wool. What do their numerous hairs represent? It is best to answer this question at the time of flowering willow. At this time, it is easy to see that willow inflorescences are of two varieties: both male and female, and they are located on different bushes in such a way that on one bush there are only male earrings, and on the other - female.

Male willow flowers are built very simply. They are devoid of perianth and are covered with only one scale in the axil, in which there are usually two (some willows have more) stamens. The scales are usually two-colored: yellowish-green below, blackish above. The upper part of the scale is covered with long numerous hairs, which give the unflowered earring a characteristic fluffy appearance. The significance of these hairs in the life of the plant is quite clear. Dressing the buds like a fur coat, they give them the opportunity to endure low temperatures and its sharp fluctuations without any harm at a time when the caps covering them fall off. Female flowers of willows have a similar structure, except that instead of stamens there is an oblong ovary thickened downwards, resembling a bottle in shape. This ovary at the top passes into a style with a bifid stigma, the sticky surface of which catches the pollen that falls on it. In addition to scales, stamens and pistils, male and female willow flowers have special nectaries at the base of the covering scales that secrete sweet juice-nectar. Willows, unlike most of our other early-flowering trees and shrubs, are pollinated with the help of insects, which are attracted, on the one hand, by fragrant nectar, and on the other, by a large amount of pollen, densely sticking to flower earrings during the flowering period.

Such a simple structure of flowers in our willows, devoid of any trace of perianth, somehow does not fit with their method of pollination; in addition, all the rest, by the way, more ancient representatives of the willow family - various poplars and aspens - are typical wind-pollinated plants. Therefore, it is now believed that willows are secondarily adapted for pollination with the help of insects, and this adaptation could have arisen in relatively recent times. This is indicated, by the way, by the large number of species of insects visiting willow flowers, reaching up to eighty. Among them we will meet bumblebees, ordinary and earthen bees, butterflies and some flies. This diverse range of pollinators indicates that willows do not have a particular specialization in this direction, while the flowers of most other entomophilous plants are strictly adapted to a particular species or group of insects. We will explore some of these devices in the next chapter.

It is also interesting to note that at present there is reason to believe that the ancestors of our willows had bisexual flowers, as indicated by the not so rare appearance of special freaks in the goat willow in the form of flowers that have both a pistil and a stamen. It is possible that the transition to dioecy gave willows a number of advantages in terms of protection against self-pollination. However, all this still remains in the area of ​​the most remote assumptions.