The spread of plants throughout the planet is a process that is constantly being improved by nature. All plant crops that are found on Earth have their own methods of reproduction, which may involve other plants, animals, natural phenomena, etc. Some methods of plant propagation by fruits and seeds are especially interesting. Such methods may seem almost like a miracle even to the most persistent skeptics. Let's talk about nature's capabilities in this matter in a little more detail.

After the seeds or fruit are formed on the crop, they ripen and are separated from the parent plant. Botanists say that the further away such planting material is, the less likely there will be competition from the parent individual. In addition, with widespread distribution, plants have a chance to colonize new territories and increase population size.

Distribution of fruits and seeds of plants

Distribution by animals

It is believed that the distribution of fruits and seeds by animals is quite reliable, since various animals actively visit areas of high fertility where seeds will grow well. Many fruits have spines or special hooks that cling to the skin or fur of nearby animals, which helps them be transported over a considerable distance, after which they will “sooner or later” fall into the ground or be torn off, but still end up in him.

Vivid examples of such plants include burdock, tenacious bedstraw, carrots, string, buttercup, gravilat, and agrimony.

Thus, gravilate has special hooks on the column, and burdock fruits are surrounded by hook-like leaves of the wrapper, and they also have small, fairly hard hairs that can penetrate the skin and provoke irritation (this leads to scratching and subsequent falling off of the fruit). Bedstraw, carrots and buttercups have a pericarp surrounded by attachment-like projections. And the string has a fly on the fruit, like a dandelion, but with fairly strong thorns.

This group of plants also includes crops with juicy fruits, for example, blackberries, plums, tomatoes, apple trees and strawberries. After being eaten by animals, the seeds pass through the digestive tract and are excreted in feces. After falling on fertile soil, such planting material germinates without difficulty.

Wind propagation

Those plants whose fruits and seeds are carried by the wind have special devices that facilitate this process. These include volatiles; they can be seen on the seeds of willow, fireweed, dandelion, and cotton. In addition, this adaptation is also typical for maple, hornbeam, ash, etc.

In certain crops, the fruit looks like a box, which is located on a stalk and sways with the wind, which leads to the scattering of numerous small seeds. Such plants are represented by poppy, nigella, foxglove, etc.

In some representatives of the flora, the seeds are so small and light that they can be carried by the wind, without having any additional devices for this. Orchids can be included in this group. In such plants, the seeds fall out after the seam between the carpels cracks. In this case, the planting material is thrown out of them with a fairly strong push. Additionally, some plants may have devices on their seeds for transport by the wind, for example fireweed.

Spread by water

Quite a few plants have fruits or seeds that are specially adapted for aquatic distribution. This planting material contains small air cavities that hold it on the surface of the reservoir. An example is the coconut, which is a drupe with a fibrous covering and a significant number of air cavities. This group of plants also includes the water lily, whose seed has a spongy shell that comes from the stalk of the ovule.

Random spreads

Botanists do not strictly divide seeds and fruits into categories depending on their method of distribution. Many crops can be spread by several or all of the above methods. The most important factor in accidental spread is humans, because seeds can easily be carried on clothing, cling to loads and thus fall a significant distance from the parent plant. Many grain crops are contaminated with weed seeds. In addition, planting material can be accidentally distributed by hurricanes, floods, etc.

The most interesting ways to distribute plant seeds

One of the interesting examples of such distribution is the process of scattering seeds by the amazing plant crazy cucumber. Its fruit is similar in appearance to a regular cucumber, and once fully ripe, the fleshy tissue surrounding the seeds becomes a slimy mass. After the fruit is separated from the stalk, pressure arises on its contents, comparable to the principle of jet thrust, due to which the seeds are scattered over a large area. This happens like a cannon shot. Common sorrel also has a similar method of seed dispersal.

Legumes are capable of pushing seeds out to a fairly large distance, and eschscholzia throws away the entire fruit along with the ripened seeds.

So, there are quite a few ways to ensure the reproduction and spread of plants across our planet.

Sexual reproduction in seed plants, which include flowering plants and gymnosperms, is carried out using seeds. In this case, it is usually important that the seeds are at a sufficiently distant distance from the parent plant. In this case, there is a greater chance that young plants will not have to compete for light and water, both among themselves and with the adult plant.

In the process of evolution of the plant world, angiosperms (also known as flowering plants) solved the problem of seed distribution most successfully. They “invented” such an organ as the fetus.

The fruits serve as an adaptation to a particular method of seed dispersal. In fact, most often the fruits spread, and the seeds along with them. Since there are many ways to distribute fruits, there are many varieties of fruits. The main methods of dispersal of fruits and seeds are as follows:

with the help of the wind,

animals (including birds and humans),

self-spreading,

using water.

The fruits of plants that are distributed by the wind have special adaptations that increase their area, but do not increase their mass. These are various fluffy hairs (for example, poplar and dandelion fruits) or wing-shaped outgrowths (like maple fruits). Thanks to such formations, the seeds float in the air for a long time, and the wind carries them further and further from the parent plant.

In the steppe and semi-desert, plants often dry out and the wind breaks them off at the root. Rolled by the wind, dried plants scatter their seeds throughout the area. Such “tumbleweed” plants, one might say, do not even need fruits to spread their seeds, since the plant itself spreads them with the help of the wind.

Seeds of aquatic and semi-aquatic plants are spread with the help of water. The fruits of such plants do not drown, but are carried away by the current (for example, alder growing along the banks). Moreover, these are not necessarily small fruits. In the coconut palm they are large, but light, so they do not sink.

Adaptations of plant fruits to distribution by animals are more diverse. After all, animals, birds and humans can distribute fruits and seeds in different ways.

The fruits of some angiosperms are adapted to cling to animal fur. If, for example, an animal or person passes next to a burdock, several thorny fruits will get caught on it. Sooner or later the animal will drop them, but the burdock seeds will already be relatively far from the original place. In addition to the burdock, an example of a plant with fruit-hooks is the succession. Its fruits are of the achene type. However, these achenes have small spines covered with denticles.

Juicy fruits allow plants to spread their seeds with the help of animals and birds that eat these fruits. But how do they spread them if the fruit and seeds along with it are eaten and digested by an animal? The fact is that mainly the juicy part of the pericarp of the fruit is digested, but the seeds are not. They come out of the animal's digestive tract. The seeds end up far from the parent plant and are surrounded by droppings, which, as you know, are a good fertilizer. Therefore, the juicy fruit can be considered one of the most successful achievements in the evolution of living nature.

Humans played a significant role in the dissemination of seeds. Thus, the fruits and seeds of many plants were accidentally or intentionally introduced to other continents, where they were able to take root. As a result, we can now, for example, observe how plants characteristic of Africa grow in America, and plants native to America grow in Africa.

There is an option for spreading seeds using scattering, or rather self-spreading. Of course, this is not the most effective method, since the seeds are still close to the mother plant. However, this method is often observed in nature. Typically, seed dispersal is typical for fruits of the pod, bean and capsule types. When a bean or pod dries out, its flaps curl in different directions and the fruit cracks. Seeds fly out of it with little force. This is how peas, acacia and other legumes spread their seeds.

A fruit capsule (for example, a poppy) sways in the wind, and seeds fall out from it.

However, self-spreading is not limited to dry seeds. For example, in a plant called crazy cucumber, the seeds fly out of the juicy fruit. Mucus accumulates in it, which under pressure is thrown out along with the seeds.

Continuation. See No. 40/2004

Interesting questions for a school botany course

14. Wood ants are known to disperse the seeds of some plants. Do you know such plants? For what purpose do ants help plants spread; do they themselves receive any benefit from the plants?

Answer. The group of entomochorous (distributed by insects), or more precisely, myrmecochorous, plants includes violets, wintergreens, European hoofweed and some others. Their seeds have edible growths that attract ants. Ants collect and transport seeds to their home over considerable distances.

16. How can you determine the time of day and predict the onset of bad weather based on the state of a water lily flower?

Answer. It is known that the water lily flower opens its petals early in the morning (at 5–6 a.m. in summer). By 7–8 pm the petals close, which allows you to roughly determine the time. On the eve of approaching bad weather (for example, rain, and it should be noted that plants feel all fluctuations in weather changes very “sensitively” and ahead of time), the petals of the water lily close and the flower is completely submerged under water.

17. It is known that fly agaric is a poisonous mushroom, but alcohol tincture of fly agaric is used for rheumatism and joint diseases. Explain the relativity of toxicity of any organism in nature.

Answer. Indeed, fly agaric is a poisonous mushroom and is unsuitable for food in any form. However, fly agaric contains chemical compounds that, in small quantities and when used wisely, can successfully treat many ailments. Thus, ancient recipes for preparing fly agaric tincture are well known, which successfully treats rheumatism, gout, varicose veins and a number of other diseases. In our difficult economic times, when not every family can afford expensive pharmaceutical drugs, we are increasingly turning to the experience of our ancestors, who were treated with herbs and herbal remedies and lived long. In addition, treatment with chemicals can also cause the opposite effect, according to the principle “one thing is cured, another is crippled.” Plant and other natural raw materials contain natural, balanced medicines created by nature itself. That is why any organism, even the most poisonous one, when used wisely, can turn out to be more healing than the most expensive advertised pill.

18. Why are the formulations “harmful organism” or “unnecessary organism” incorrect? Use specific examples to show that there are no harmful or unnecessary organisms in nature.

Answer. Of course, it makes no sense to claim that this or that organism is “harmful” or “unnecessary”. From the point of view of nature, each organism performs its own function, its own “purpose”. People call organisms “harmful” based on their concepts of “benefit” - such statements are very conditional and ambiguous. For example, mosquitoes, from a human point of view, are harmful organisms because they cause him a lot of trouble. In addition, mosquitoes are carriers of a rather dangerous disease - malaria. However, in nature everything is interconnected and interdependent. Mosquitoes are an important link in the food chains of a forest community, and their disappearance could undermine the stability of the community. The same can be said about insects - forest pests. They damage wood used by humans for various needs, but serve as food for forest birds. The reduction or disappearance of such insects in the forest will lead to a reduction in the number of some birds. We can conclude that all organisms in nature are necessary and important and are closely related to each other.

20. What is "sea kale"? Is it related to food plants from the cruciferous family? How does a person use seaweed?

Answer.“Sea kale” is a kelp algae that has nothing to do with plants from the cruciferous family. It belongs to the subkingdom of lower plants, the department of brown algae. However, it was not by chance that seaweed got its name. Like ordinary cabbage, sea cabbage uses “leaves”—leaf-shaped thallus—for food. “Sea kale” is not only edible, it is rich in iodine, which is necessary for the normal functioning of the human thyroid gland. Sea kale salad is included in the daily diet of many residents of China, Korea, and Japan. In these countries, artificial plantations have even been created for growing “sea kale”.

21. What advantages do plants with large seeds have and what advantages do plants with small seeds have? Give examples of such plants.

Answer. The size of plant seeds is not random; they are related to the method of distribution, the ecology of the plant and the history of the formation of the species, genus, family to which the plant belongs. Large seeds have a greater supply of nutrients, which provides the germinating plant with relative independence from external conditions at first. However, as a rule, fewer large seeds are produced than small ones. Large sizes impose certain restrictions on the methods of distribution - such seeds cannot be spread by wind or insects. Large seeds are more visible to animals and easier to prey on, and therefore must either contain large amounts of toxic substances or have dense covers that are resistant to the action of gastric juices.
Small seeds contain less nutrients, and therefore the seedling has less chance of survival, especially if environmental conditions are unfavorable. Plants with small seeds compensate for the quality of seed germination by their quantity. Small seeds are easily transported by the wind over long distances and can be carried into burnt areas and clearings.

22. Why does grain stored in warehouses and warehouses need to be repeatedly transferred from one place to another during the winter?

Answer. The grain contains the embryo of a plant, which is characterized by such manifestations of vital functions as respiration. When you breathe, carbon dioxide and water are released. The released moisture can cause the seeds to dry out or become moldy if they are not periodically transferred from one place to another during the winter.

23. It is well known that plants, like animals, are characterized by the elimination of unnecessary substances from the body. What substances are not needed by the plant organism and how are they removed in this way?

Answer. Through the leaves, the plant releases oxygen produced during photosynthesis, as well as carbon dioxide produced during respiration. Plants that inhabit saline substrates secrete excess salts through special glands on their leaves (for example, tamarisk, kermek). Scientists are well aware of the fact that substances that are not needed by a perennial plant accumulate in necrotic and dying tissues and organs: before the leaves fall, for example, a tree “pumps” into it all unnecessary substances, including toxic ones, thus getting rid of them during leaf fall.

24. What functions can pubescence of stems and leaves perform in plants of different species? Explain with specific examples.

Answer. The functions of pubescence are very diverse. Hairs on the stems and leaves can protect the plant both from overheating and excessive evaporation, and from being eaten by insects. Glandular hairs are capable of secreting various substances, for example, attracting pollinators or allowing plants to “communicate” with each other (this phenomenon is called allelopathy). The hairs on the petals of a number of flowering plants serve as food for pollinating insects. Also, hairs on flower petals can serve as indicators of the direction of movement of pollinating insects that have visited the plant in search of nectar. In other plants, the hairs inside the corolla of the flower can serve as a kind of barrier for small insects that are not able to pollinate the plant, but visited it in search of nectar. Stiff hairs inside the corolla of the flower of some plants can function to hold the insect inside the corolla until pollination occurs and the turgor in the hairs weakens. In sundews, the hairs on the leaf blade secrete a sticky liquid and enzymes that help digest insects. The pubescence of the seeds can serve as a device for attachment to the skin of a dispersing animal (succulent), or for dispersal by the wind (dandelion).

To be continued

Fruits and seeds often end up very far from the plants on which they ripened. This is explained by the fact that some fruits and seeds are carried by the wind, others are spread by animals, humans, water, and some by self-dispersal, like the acacia and the mad cucumber.

The wind spreads seeds of poplar and some other plants.

Poplar seeds, covered with white fluffy hairs, ripen in May. Falling from the branches, they are carried by the wind and accumulate on the ground, resembling snow flakes. Thanks to the fluffy hairs, the wind carries poplar seeds over long distances. Dandelion fruits also spread.

Rice. 9.: 1 - dandelion; 2 - rowan; 3 - burdock; 4 - sequence.

Maple fruits have two winged outgrowths. Falling from the branches, the fruits quickly spin in the air. Therefore, they do not fall to the ground for a long time and are carried far away from the tree. The wind easily breaks off some dried steppe plants at the root, carries them along the ground, rolling them from place to place, and the seeds are scattered. Steppe plants driven by the wind are called “tumbleweeds.”

Spread by water fruits and seeds not only of aquatic plants, but also of terrestrial ones. For example, the fruits of alder, which often grows along river banks, fall into the water and are carried away by the current far from the mother plants. The fruits of the coconut palm often fall into the sea and float for a long time before they land on the shore and germinate.

The seeds of many weeds are sometimes unwittingly carried by animals and people. Thus, a burdock basket with fruits, called infructescence, clings to animal fur or human clothing, and the fruits end up far from the plants on which they ripened.

A series of weeds grows in ditches, near ponds and rivers. Its inflorescences are small yellow baskets, and its fruits are achenes with spikes covered with denticles that bend back. A dog will run through the thickets of a row, another animal or person will pass by - and the small thorny fruits will tightly cling to wool or clothing, so much so that you cannot clean them off with a brush, you have to pick them out with your hands. There are plants not only with tenacious fruits, but also with sticking fruits. These are the fruits of forget-me-nots.

Seeds of plants with juicy fruits - rowan, elderberry, lingonberry, blueberry, bird cherry, lily of the valley - birds spread. They eat these fruits and, flying from place to place, throw out intact seeds of the eaten fruits along with their droppings.

Rice. 10. Distribution of fruits and seeds: 1 - birch; 2 - maple; 3 - crazy cucumber; 4 - max.

The fruits and seeds of some plants stick or cling to bags and bales of cargo and end up in secluded corners of carriages, cars, and airplanes. When unloaded, the seeds fall to the ground, germinate and often find a new home. Thus, at one time, plantain was brought from Europe to America, which is found on paths and roads. That is why the indigenous people of America - the Indians - call the plantain "the white man's footprint."

Self-spreading seeds can be observed in many plants. For example, in the summer on a hot, sunny day near the yellow acacia bushes you can hear a slight crackling sound - this is the ripened acacia beans cracking and scattering their seeds.

They scatter their seeds and fruits of peas, beans, and beans. Therefore, the fruits of these plants must be collected without waiting for them to dry completely. Otherwise, they will open, throw out the seeds, and the crop will die.