Seeds are quite rare, but germinate directly in the plant. For example, by cutting a ripe pumpkin, we can observe already sprouted seeds in it. However, basically they do not germinate where they mature, but in a completely different place. What are they - ways of distribution of fruits and seeds of plants? How does this happen and why? Let's find out!
What is a fetus?
Before we examine in detail the methods of distribution of fruits and seeds, these same concepts should be studied. Indeed, without elementary knowledge, it will be difficult for us to understand the whole process and mechanism of the “travel” of seeds and fruits around the world. So, let's begin. It is no secret that pear, plum, apple, strawberries, cherries are the fruits of fruit plants and trees that contain seeds. It is believed that they develop from the ovaries and other parts of plants, but not all botanists agree with this.
Some of them are sure that only those that are formed exclusively on the ovaries, for example, in cherries, plums, tomatoes, poppies, etc., can be called real fruits. Fruits that develop from other parts of flowers and plants are commonly called false. For example, strawberries are generally formed by an overgrown receptacle. What kind of ovary can one talk about here! As a result, scientists decided to consider the fruits as a result of a modification of the entire flower. Moreover, if at the beginning of their "life path" they can somehow still retain some of the signs of a flower, then after ripening they completely lose or greatly modify them.
How are the fruits of plants
Outside, each fruit is surrounded by a so-called pericarp, which protects seeds ripening inside from damage and drying out. In turn, the pericarp is divided into juicy and dry. For example, the flesh of a ripe watermelon, melon or peach can be called a juicy pericarp. The immature pericarp is astringent, bitter, sour, and tasteless. During this period, it protects the fetus itself from untimely eating, and its still immature seeds - from soon spoilage.
Types of fruit
To understand how the seeds and fruits of certain plants and trees are distributed, you need to know that the following are related to the juicy fruits of botany:
- multi-seeded (pumpkin, berry, apple, pomegranate);
- single-seeded (peach, apricot, mango, cherry, bird cherry, prunes).
As the name of the fetus implies, in single-seed there is one bone. They are also called drupes. However, there is an exception here: for example, a blackberry is a multi-seedling, but it is a single-seeded fruit.
The methods of distribution of fruits and seeds directly depend on their size, weight and shape. As mentioned above, the fruits are juicy and dry. Dry, in turn, are divided into opening and not opening. For example, the pericarp of ripe beans, pods, and also poppy boxes are opened (burst) after maturation. But, for example, the pericarp of hazel is very solid and numb. He himself will never open up in the world. He has one single seed that we know very well: nut.
Another type of fruit is the box. Usually it has 3 to 5 nests with seeds. When these seeds ripen, then their "house" begins to burst. For example, St. John's wort or tobacco boxes crack along their partitions, after which they break up into separate parts. At the same time, at the “houses” of lilies, hyacinths, tulips and cotton, only the walls crack, and at poplar and willow, the boxes generally crack at the seams. The most famous box is the pod, which, during ripening, splits into two leaves with a bang.
Is a berry considered a fruit
Yes. This is a kind of fruit that has many seeds in its composition, but does not have seeds. If the berry is ripe, then it appears juicy and fleshy pericarp (grapes, strawberries, lingonberries, cranberries, blueberries). That is why, from the point of view of botanists, cherries are not berries, and tomatoes are! This also includes citrus fruits, which are also berries:
- tangerines;
- oranges
- lemons;
- oranges;
- grapefruits.
The fact is that nests with seeds located inside the aforementioned fruits are filled with fragrant exotic juice. The fruits of the pumpkin family can also be called berries:
- melons
- watermelons;
- cucumbers.
Of course, it hurts a simple layman, but professional botanists have long been accustomed to the idea that formally a watermelon and a cucumber are not only berries, but also relatives.
What does the seed look like inside
Distribution of fruits and seeds (Grade 2, familiarization in students' biology classes with various methods of “traveling” the seeds and fruits of various plants) is unthinkable without the participation of humans, animals, and, of course, water and wind. But in order to understand how such a small seed can "travel" around the world, you need to briefly familiarize yourself with its structure. So, any seed is peeled. On smooth seeds, a scar is visible, which forms in those places where it is separated from the placenta.
If you look closely, then next to such a scar you can see a micropolar hole, referred to in the scientific community as a micropile. Somewhere nearby there is a root tip. It is he who, during the germination of the seed, appears the very first to come out. The dense peel protects the seed from various injuries and at the same time passes moisture, without interfering with the germination of the embryo - the main part of all seeds. It is formed only after fertilization of the egg and usually consists of a stem, root and kidney.
How are plant seeds distributed in nature
Well, here we come to the main thing. As mentioned above, rarely sprouted seeds give life to new plants, since in the vast majority of cases they do not grow where they matured. Why is this happening? It's simple: they “travel” to new places through people, animals and mother nature herself! If the conditions for a new life are quite suitable, these seeds will begin to sprout, and if not, they will die.
- An excellent way to spread them is through cross-pollination of plants, due to which new species of flora can be formed. This is the minimum that gives life to new plants. Of course, the methods of distribution of fruits and seeds of plants are not limited to pollination.
- Unpleasant to the taste or even poisonous fruits and seeds are very attractive food for birds. At the same time, seeds that have a hard shell are simply not able to digest in their stomachs. As a result, they, along with bird droppings (guano), are transported over long distances from the place of their original "birth". But the role of birds in spreading a new life of plants is not limited to this!
- Many birds, arranging their reserves for the winter, drag the seeds and fruits of various plants into nests. Some of them are simply lost during the flight of birds, falling to new places. For example, jay birds are constantly stocked with acorns, some of which are lost and grows over time.
- Another helpers in germinating seeds and fruits are ants. These small, but useful in nature creatures carry the seeds of a wide variety of plants, especially those rich in essential oils (cornflower, celandine, medunica, sour, violet), to their nests. Like birds, ants lose the lion's share of the collected seeds along the way. By the way, it’s the grass seeds that are mostly accessible to these little thugs.
How else do the fruits and seeds of plants “travel”
They are mainly spread by wind. Seeds in this case fly apart much better than the already formed fruits. But more on that later. As you know, in nature there are so-called “living” fruits that independently cling to the hair of animals that accidentally run past, and also stick to a person’s clothes. For example, those are the fruits of burdock, a string, a cocklebur and burdock.
Here, botanists especially note pisonia - a shrub or tree that grows on the islands of the Pacific Ocean. The fruit of this unusual plant is enclosed in a special cup, seated in rows of various sticky hairs. They allow the fruits of pisonia to stick easily to any animal or object. Often in nature, you can see reptiles and small birds, completely covered with such fruits. Unfortunately, in this case, the animals cannot fully move and die.
"Travel" by air
You know that fruits and seeds can spread through the wind, i.e. by air? For example, this happens in the high steppes, in the savannahs and deserts, where strong winds constantly walk. In this case, the seeds just scatter in different directions and over great distances. Seeds having a flat shape and small size (bell, hops, heather, broomrape, eucalyptus) are especially good.
Winged seeds and fruits
It will be interesting to learn how seeds with the so-called wings are spread by wind. They appeared in those plants that grow exclusively in open areas. These “wings” are specific hairs with which seeds are completely covered (for example, in anemone). In poplars and willows, seeds are generally equipped with tufts consisting of the finest hairs.
In hazel, hornbeam, alder and birch, the fruits are small nuts equipped with wings. One wing has the fruits of tulip trees, ash trees and maples. Incidentally, this is why they spin when falling. The seeds and fruits of sedge swollen, cystic, astragalus are spread by wind. It is curious that in these plants they travel in balloons, which are formed with the help of air sacs covering them.
Tumbleweed
Probably everyone at least once heard of such a bizarre plant. His scientific name is swing panicle. In autumn, it tends to completely detach from its root. The loose and spherical bushes of this plant with ripened fruits are spread by the wind. Seeds of paniculata kachima are hidden in boxes, the teeth of which have a shape bent inward. This allows the seeds to get enough sleep only during rather strong gusts of wind, blowing them over long distances.
