Seed spreading - necessary condition for the existence and prosperity of plants. In the process of evolution, fruits and seeds have developed many adaptations for distribution.
Depending on the seed and fruit spreading agent, all plants are divided into 4 groups:
1) anemochoric - spread by the wind;
2)zoochorny – spread by animals;
3) hydrochloric - spread by water;
4)autochors - spread by self-spreading.
Most trees in the upper canopy of the deciduous forest spread their fruits and seeds with the help of the wind.
The seeds of these trees are lightweight. For example, 50,000 aspen seeds have a mass of 4 g. And there are plants whose seeds are many times lighter: the mass of a broomrape seed is 0.000001 g; wintergreens - 0.000004 g. Winged birch fruits can fly 1.6 km away from the mother plant. Its seeds can move much further away from the spruce. Their wings are like a sail. And the seeds slide over the crust. Maple and ash lionfish travel near their native trees.
Some plants have parachutes, which consist of branched hairs that increase the sail surface of the parachute. In this respect, the fruits are indicative. dandelion, goatbeard or sow thistle... Such fruits can fly away in the wind over a huge distance.
In a number of plants, flying devices help not only the movement of seeds, but also, like a gimbal, burying them in the ground. Grain is often found in the steppes feather grass... The fruit is its sharp weevil with a long awn curved at right angles. Part of the spine is pinnate. Its lower part, when dried, twists in a helical manner, when moistened, it unwinds. Having met during its movement along the steppe, any obstacle - a pebble, a lump of soil, a stem of a plant, a caryopsis with its sharp end is screwed into the ground.
In the steppes, the wind picks up whole plants, breaking them at the root, and carries them, rolling them from place to place. Tumbleweed- so called the people driven by the wind, jumping dry plants. For a long journey across the tumbleweed steppe, the field carries its seeds over long distances.
Some of the fruits and seeds are spread by water. The ripe fruits of the coconut palm are dumped into the sea and carried away by the current. Carried by the water to new shores and thrown out on a sandbank, they sprout and form new coastal groves. Thus, even in very distant times, coconuts settled along the shores of continents and islands - wherever they were warm enough.
Hydrochoria is observed in plants growing in water or along the banks of water bodies (pond, water lily, arrowhead, sedge, alder). Their fruits, falling into the water, do not drown. The current carries them away from the mother plants.
Self-spreading can also be observed in many plants. For example, if you touch the fruit of a touch-me-not plant, then its shutters break, twist and forcefully scatter the seeds. The same thing happens with peas and beans. Therefore, they are harvested without waiting for the fruit valves to dry completely, otherwise they will throw out the seeds and the crop will die.
Probably everyone heard on a clear day a slight crackling and clicking in the yellow acacia bushes. The pods heated by the sun crack, then curl, the seeds scatter in all directions.
In the Crimea and the Caucasus, on dry slopes and sea coasts, you can find the weed plant mad cucumber. After the seeds ripen, mucus accumulates in its fruits, which, together with the seeds, is forcefully thrown out of the fruits. It seems as if a mad cucumber is shooting its fruits. In many plants, ripe fruits, when dried, burst violently and throw the seeds over a considerable distance, for example, in marsh geranium at a distance of 2.5 - 3 m, in a dog violet - by 4 - 5 m, in begonia - up to 15 m.
The seeds and fruits of many plants are sometimes unwittingly spread by animals and people.
Many people grow under the forest canopy. berry bushes: rose hips, viburnum, elderberry, euonymus, wolfberry and others. There are also low trees: bird cherry, mountain ash and others.
Plant seeds with juicy fruits eaten by animals, mainly birds. They eat these fruits and, moving from place to place, together with the droppings, they throw out the intact seeds of the eaten fruits. During their autumn migrations, birds carry seeds adhered with mud, especially of aquatic and coastal plants.
The fruits of plants such as burdock or burdock have sharp teeth and hooks. With their help, these fruits cling to the hair of animals or to the clothes of people, which carry them over considerable distances.
When transporting goods, the fruits and seeds of some plants can stick or cling to bags or bales. When unloading, they fall, and the plants that have grown from them are often found in new territories. good conditions for life.
An interesting way spreading fruit associated with self-closure (peanuts). After flowering, the pedicels lengthen greatly, then bend to the ground and bury the young fruits at some distance from the mother plant. In the ground, the fruits ripen and germinate.
So plantain, a common plant of paths and roads, was brought from Europe to America at one time. The indigenous people of America - the Indians - call the plantain a trace white man... And the weed of our southern fields odorous chamomile was brought to us from America.
Plants strive to reproduce in all conceivable and inconceivable ways, however, it is worth remembering that not only seeds are important for the further spread of plants in a particular territory. Very important for cultivated plants It has environment and climatic conditions... Only in the presence of heat, moisture and oxygen can the plant develop. If at least one of these components is missing, then the plant dies. So let's take a look at how seeds are spread.
Seed distribution methods
It is for this reason that many seeds strive to get into an acceptable climate as soon as possible. Biology knows at least eight ways of spreading seeds of cultivated plants. Let's take a look at each of the ways in which plant seeds are distributed.
- The first way of spreading the seed is its external fitness and readiness for it to be transferred to long distance... For example, great amount seeds have such devices as thorns or hooks with which they can attach to human clothing or animal hair and be carried over distances.
- The second type of seed is adhesion. They are located in rather sticky berries of plants. Such berries are eaten by birds, and when they begin to peck them, the seeds attach to the feathers and travel very long distances on the bird.
- In addition, there is another not quite usual way of how fruits and seeds are distributed. It lies in the fact that such plants grow near water bodies or even in water. The seeds are mixed with mud or water, after which they are transferred on the paws of animals or on the shoes of people. Also, these seeds can stick to the paws of birds with dirt.
- In addition, there are some plants that are eaten by animals. They are eating delicious filling, do not think that at the same time a lot of seeds have stuck to their mouths, and when they fly away to travel, the seeds are transported over long distances with them.
- However, do not belittle the human influence on the spread of seeds. wild plants on the ground. We carry thousands of plants on our clothes without even knowing it. For example, when we collect very small seeds, we often sift out those that do not fit in size or for some other reason. It is attached to our shoes or clothes and transported to distant lands.
- However, seeds can be scattered on the ground and by the wind. Seeds are spread, thus, through the air quite independently. These are various fluffy devices that help the seed to control its flight. Some seeds even have small wings or parachute-like attachments.
- The next category of seeds that spread independently are the so-called "swimmers". They move around the reservoir with the help of the flow of the river.
- There is also a special category of plants that explode in order to spread their seeds over distances. After full ripening occurs, the fruits of the plants dry out and burst, throwing the seeds over a considerable radius.
Thus, plants spread not only with the help of living beings, but also independently.
After seed formation, either the entire fruit or the seeds (or seed) it contains are separated from the parent plant. The longer the seeds spread, the less likely competition from the parent plant is. It also gives a better chance of colonizing a new territory, which over time leads to an increase in the size of the population as a whole. The methods of dispersal of seeds and fruits in flowering plants are very diverse.
Propagation by animals. Fruits equipped with thorns or hooks cling to the skin or fur of passing animals and can be carried a certain distance before being ripped off or falling off. Examples are the fruits of the tenacious bedstraw, gravilata, burdock, burdock. Many plants bear fruit with a succulent pericarp to attract birds and animals. The seeds of these fruits are protected from digestion in the digestive tract and, together with excrement, enter the soil, germinate, but in a different place.
Spread by the wind. Many plants that are spread by the wind have special adaptations. These include flyworms (seeds of willow, fireweed, cotton, dandelion fruits, etc.) and lionfish (in pine (gymnosperms), yaz, ash, maple, hornbeam, etc.). In a number of plants, for example, in the poppy, the fruit is a box sitting on a leg, which is swayed by the wind, so that numerous small seeds are poured out through the pores in the upper part of the fruit.
Spread by water. Few fruits and seeds are specially adapted to be spread with water. They contain air pockets that hold them on the surface of the water. Coconut is a drupe with numerous air cavities. In a water lily, the seed is equipped with a spongy shell, the air pores of which prevent them from sinking.
Self-spreading Plants are spread in which seeds are thrown out due to an increase in internal pressure in the fruits, or the pericarp throws out seeds according to the principle of springing or throwing. Such a spread of seeds is characteristic of mad cucumber, common sour cherry, legumes, in many iris, lily, primroses. Plants spreading seeds usually grow in places where, for one reason or another, it is impossible to use other routes of settlement (wind, animals). Most often they live in remote corners of the forest, where there is almost no wind, and where animals rarely pass.
In many cases, there is an element of chance in the spread of seeds and fruits, and a given fruit or seed can spread in two or even all three ways. One of the main contributors to accidental spread is humans; the seeds can cling to or stick to his clothes, etc., or be transported with different loads in vehicles. Contamination of crops with weed seeds is common throughout the globe... Nuts cached by rodents may remain and germinate next spring. Floods, hurricanes, etc. can carry seeds further than usual. There are also fruits that can crawl and jump (oats, feather grass, etc.).
It would seem that in winter it is difficult to observe the life of plants - trees and shrubs are in deep sleep, the grass is hidden under the snow. However, it is in winter that we begin our botanical excursions - the second half of winter is suitable to start germinating seeds on the windowsills, replanting houseplants.
Let's start by getting to know the seeds. During the walk, collect wilted, but retained the shape of inflorescences of herbs and weeds that grow in the city (wormwood, tansy, yarrow, plantain, etc.). Place them in a plastic bag immediately, buds down. You can also pick the fruits of trees and bushes that remained on trees in winter - ash, lilac, mock orange, mountain ash, pine and spruce cones.
Take home White list paper and shake the seed pods over the sheet. The berries can be cut in half, the boxes can be carefully opened.
What a variety of seeds! Consider their shape, size. You can sketch the inflorescences or fruits - and the seeds that were in them, in close-up.
The task of the plant is to provide its "children" -seeds as much as possible comfortable conditions for growth. This means that the seeds should sprout as far from the parent plant as possible, so as not to interfere with each other. Therefore, all seeds travel in one way or another. Take a look at the seeds you found.
Plant Seed Propagation Methods
If there are pine or spruce cones among them, carefully open the cone scales. A small lion-seed is hiding inside. Throw it up - the seed, whirling, will fly to the ground. Pine and spruce seeds travel by air... Try to remember what other plants send their children “flying "? (Maple, linden, birch, dandelion, thistle)
If you come across berries, remove the seeds from the pulp. They also travel, but in a completely different way. Rowan seeds are carried by waxwings, blackbirds and bullfinches. The berry is a bait for the bird, but the seeds themselves are not digested by the bird. Together with bird droppings, the seed will be in a new place. What other plants enjoy the bird's love of food? (In winter - hawthorn, viburnum, chokeberry. In summer - cherry, strawberry, raspberry)
By the way, with the help of birds and squirrels, he is looking for a new place to live and an oak tree. Oak fruits - acorns - with pleasure store jays and squirrels for the winter... Only now they do not always remember about their reserves - a jay, for example, hides up to a hundred acorns per season, but finds - no more than half. The rest of the acorns will sprout in the spring in a new place ... (In the forest, hazel - hazelnut "travels" in the same way).
Plants also have one more way of movement, in which both animals and humans help him. Have you come across plantain inflorescences sticking out of the snow? There is a legend that in America the Indians called this plant "the footprint of the white man." Why? It turns out that plantain seeds are sticky, they stick to the soles of shoes... On the soles, the seeds climbed over Atlantic Ocean, where they climbed along the sides of paths and roads along which migrants from Europe traveled. By the way, Russian name plantain also hints to us about this cunning way of moving.
But not only plantain travels in this way - for clothes and animal hair with tiny "hooks" agrimony and string, sticks to the soles of wormwood. Children can definitely remember the plant, which they themselves helped, playing with its tenacious balls - this is a burdock with its burdock fruit, which hangs so well on jackets and shirts.
In our climate, we will not find plants that used to move the waterways of communication. But there are some plants that actively use them. One exhibit is kept in the Botanical St. Petersburg: a huge seed. He was found in 1921 on the shores of the Arctic Ocean. Seeds of this size do not grow in the harsh northern climate, so the find was handed over to the Botanical Museum. Here the seed was identified - it turned out to be a giant seed tropical plant entads, "elephant creepers". Most interesting feature of these hard seeds with a thick, durable cover - their great buoyancy, entada seeds can float in sea water and not drown for a whole year. Sea currents carry these non-sinking seeds to all tropical countries. One of these seeds sailed to the coast of the Arctic Ocean. You can try to plot his route on the map! From the shores of tropical America across the entire Atlantic Ocean to the shores of northern Europe, there is a huge current, the Gulf Stream. The seed, apparently, began its journey somewhere on the coast of the Antilles, ended up in the Gulf of Mexico, where it was picked up by the Gulf Stream and carried past the Florida peninsula to the north, and then across the Atlantic Ocean. Sailing between Iceland and Norway to the European shores, the seed fell into the cold Barents Sea. It was then in bad weather that he was thrown onto the sand. Coconuts know how to travel in the same way.
You still have the seeds you looked at. If you have the opportunity - try to plant them! The pot is best covered plastic bag, thus creating a small "greenhouse". You can sign pots and hold a real scientific work- observe which seeds will sprout first, which seedlings will be more.
I invite you to share your observations and additions on how the seeds move in the comments! Really curious! And of course I'm waiting for a photo
Distribution of fruits and seeds. Each flowering plant forms a large number of seeds. But it is also very important for the plant to ensure their distribution. Indeed, thanks to this, the species settles.
The methods of distribution of fruits and seeds in flowering plants are very diverse: with the help of wind, water, animals, and also independently, through the use of mechanical forces arising in the plant itself.
Many plant species scatter their seeds in one way or another. For example, in a mad cucumber, when ripe, the pulp of the fruit with seeds is vigorously sprayed over many meters, for which it got its name. And the fruits of touch-up, or balsam, after ripening, crack from the usual touch, scattering the seeds. Some species scatter seeds, quickly spreading out the elastic stem or peduncle (for example, lilies, primrose). Almost all plants with dry, opening fruits scatter their seeds to one degree or another after they are ripe.
The most in the usual way resettlement of plants is the spread of their fruits and seeds with the help of the wind. Probably, there is no such person who would not play in childhood, inflating the fluffy "parachutes" of a dandelion, carrying light fruits. There are a lot of plant species, the seeds of which have such adaptations, in nature. Large fruits have other adaptations for spreading by the wind, often in the form of lamellar pterygoid processes (like maple). Very small seeds, even without special devices, are easily picked up by the wind. For example, 500 thousand seeds of some types of tropical orchids weigh no more than a gram.
All of you know or have heard about tumbleweed. This is the name of several types of steppe or semi-desert plants, a dried spherical bush of which is rolled by the wind, scattering seeds. At the same time, the seeds do not spill out all at once, but gradually, which ensures their distribution over large areas.
Many plants use the flow of water for their settlement. These are primarily wetland species, such as water lilies and others.
In many plants, fruits or seeds have adaptations for distribution by animals. Pericarp of all juicy fruits contains nutrients... But they are not intended to feed the plant embryo in the seed, but to the animals that ensure their distribution. For example, each of you paid attention to autumn garden or park on picturesque bunches of mountain ash. The fruits of this plant are readily eaten by various birds. Rowan seeds have a dense shell and, having passed through the intestines of the bird, do not lose their ability to germinate. Together with bird droppings, they will be thrown away from the mother plant.
Probably, more than once each of us cleaned our clothes from tenacious thorns. different plants... Spiky burdock, burdock or sticky sage fruits usually cause some inconvenience to animals and humans. Attached to clothing or wool, they often "travel" with a person or animals over considerable distances.
The use of fruits and seeds in economic activity person. You are aware of many types of plants, the seeds or fruits of which a person eats or feeds pets. These are delicious fruits of fruit and berry (for example, apple, pear, cherry, plum, grape, citrus) and vegetable (for example, watermelon, melon, cucumber, tomato) crops. A variety of cereals are produced from the fruits and seeds of grain crops (barley, wheat, rye, rice).
Oils are obtained from the seeds and fruits of many plants (for example, sunflowers, flax, camelina, peanuts, soybeans, corn, some palms). Fruits and seeds are also used in various industries. So, cotton is used as a raw material for the production of fabrics from vegetable oils make drying oil used in the paint and varnish industry, machine oils.
The fruits and seeds of many plants are used to treat various diseases human and domestic animals. For example, the fruits of raspberries, blackberries, viburnum and other plants are used in the treatment of colds.
The fruits and seeds of some plants accumulate substances that give them a sharp or bitter taste. They are used in cooking as seasonings that improve taste qualities varied dishes. There are plants whose fruits accumulate toxic substances. For example, lily of the valley berries, when consumed, can cause nausea, vomiting, heart problems, and even cause cardiac arrest. Many toxic substances accumulate in fruits (especially immature ones) and seeds of plants from the Solanaceae family (black henbane, belladonna). Poisoning with these plants causes severe disruption to work. different systems organs (nervous, circulatory, respiratory), and in severe cases - leads to death. Therefore, never eat the fruits of unfamiliar plants, even if they are very attractive in appearance.
Sometimes the spread of plants in a particular area becomes a real ecological disaster. An example of this is the appearance of the prickly pear cactus in Australia. At first, it was brought in as ornamental plant and grown indoors. But over time, prickly pear settled in natural conditions over large areas. The pastures have become unsuitable for grazing animals due to the long and sharp thorns of the cactus. I had to bring from Mexico (the homeland of this plant) the natural enemies of prickly pear - caterpillars of one of the species of butterflies, which quickly reduced the number of these plants. Using this example, we can see how ill-considered human actions and the damaging ability of plants to spread can lead to grave consequences... On the other hand, we have an example of application biological method, thanks to which with the help of some organisms it is possible to limit the number of others.
Pollen is very nutritious, it contains up to 40 - 50% proteins, about 40% carbohydrates, there are fats, vitamins and other useful substances. Therefore, the pollen of certain plant species is used in medicine.
Scientists have found Manchu lotus seeds, which are about 400 years old. However, they did not lose the ability to germinate.
Each tobacco plant is capable of forming up to 360 thousand seeds.
Watermelons - several species of one- and perennial dicotyledonous herbaceous plants - originate from the Kalahari Desert in South Africa and are distinguished by their thermophilicity and drought resistance. One of the annual types of watermelons is grown in Ukraine. Its sweet berry-like fruit is rich in sugars and vitamins and can weigh over 30 kg.
There are very few insect-pollinated plants whose flowers have a solid, bright red color. This is due to the fact that insects, unlike humans, do not distinguish between red. And yet, this color of flowers is found, especially in the tropics. But they are not pollinated by insects, but by small birds: sunbirds in Africa, tiny hummingbirds in America. The eyes of these birds are extremely sensitive to everything red.
Flying mammals from the order of bats (these include our the bats) in tropical countries pollinated different kinds night plants. These animals have small size(a few centimeters), a narrow elongated muzzle and a long tongue, with which they extract nectar and pollen.
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