Most of all in his economic activity a person uses the fruits of plants. Juicy peaches, fragrant strawberries, ripe tomatoes, exotic avocados - everyone can choose a treat to taste. But despite the amazing species diversity, all fruits have common structural features. Let's consider them in more detail.
What is a fetus?
The fruit is a modified flower. It appears after pollination and fertilization processes. Fruits are formed only as a result of the flowering of a flower. Therefore, they can only boast of flower (angiosperms) representatives of the plant kingdom. Neither the highest spore, nor gymnosperms bloom, and therefore do not form fruits.
There is a legend that a person who finds a fern flower is endowed with magical properties. But scientists have long established that spore plants do not form flowers.
The second misconception is that cones are the fruits of conifers. Botany refutes this assumption. Gymnosperm conifers do not bloom, which means they cannot form fruits. Cones of spruce and pine - this is just a modification of the shoot. And scientists call small "berries" of a juniper as cones and also consider modification of an escape.
Structure
More often than not, most of the fetus is occupied by the pericarp surrounding the seed. Its second name is pericarp, which in Greek means "around the fruit." This structure in all plants consists of three parts: external, medium and internal. The outer layer is used to protect against mechanical damage. Therefore, it is either leathery or very durable. To attract animals through which seeds are distributed, this layer is often brightly colored. In the middle layer is a supply of water with the nutrients necessary for the protection and development of the seed. The inner layer further protects the seed. For example, a plum has a leathery outer layer, fleshy middle. And the inner one is represented by a bone. In an apple, the structure of the outer layers is similar, and inside are membranous chambers in which seeds are located.
Pericarp is formed mainly due to the walls of the ovary (cherry, plum). Sometimes other parts of the flower also take part in its formation: the receptacle, the base of the stamens, sepals, and petals.
Inside the pericarp is a seed that develops after fertilization from the ovum.
Pericarp reliably protects the seed from adverse conditions, protecting from mechanical damage and temperature extremes. It is thanks to the presence of fruits that flowering plants have occupied a dominant position in the plant world. After all, their seeds are reliably protected from the cold and serve as a source of nutrition during the formation of the seedling. This gives them a significant advantage over spore and gymnosperms, spores and seeds of which are not protected by anything.
Classification
The taxonomists systematists put several signs at once into the classification of fruits. According to the structure of the pericarp, they are dry and juicy.
Lignified or leathery pericarp of dried fruits contains a small amount of water. But juicy, on the contrary, it is fleshy and contains a lot of nutrients.
By the number of seeds, single-seeded and multi-seeded fruits are distinguished. Distinguishing them is very simple. A single seed is a single-seed fruit, such as a plum or a cherry. Peas, sunflowers, poppies form multi-seeded fruits. As the name implies, they contain many seeds.
One simple fruit is formed from a flower with one pestle. If there are several pistils in the flower, the corresponding number of small fruits is formed. Together they form a complex or precast, such as raspberries or blackberries.
Another variety is fertility. What are they? They are formed by the fusion of individual fruits. In nature, they can be found in mulberries or pineapples.
Single Seed Fruits
Single-seed fruits can be either juicy or dry. Single seed dry fruits are widespread in nature. They are of great economic importance. So, coffee - the fruits of a coffee tree - is used to make a fragrant hot drink. The fruits of oak acorns are rich in starch. They are used as animal feed. One seed is an almond fruit - a fragrant nut with valuable taste.
Juicy single-seeded fruits serve as a favorite treat for animals and humans. Cherry, sweet cherry, peach, apricot, plum - juicy and sweet taste is familiar to everyone.
Single seed dry fruits
In cereal plants, the pericarp is tightly fused with the seed peel. Therefore, a grain is often called a seed. Examples of such plants are oats, rye, wheat, corn, feather grass.
Achene differs from caryopsis in that its pericarp does not grow together with the seed coat. Such fruits are in asters, chrysanthemums and sunflowers.
To find out which fruit is single-seeded, you can get acquainted with the structure of the lionfish. Its pericarp grows into a lobe and, like a wing, spreads seeds of ash, birch, linden and elm with the help of wind.
The single seed is the fruit nut. He has a lignified pericarp. No wonder some people are compared with him, calling them a tough nut.
Single seed juicy fruit
You can get acquainted with the structure of juicy fruits by the example of drupes, in which all three layers are clearly distinguished. It has a leathery exocarpy, fleshy mesocarpy, and a ligneous endocarpy forming a bone. Juicy single-seeded drupe fruits inside the seed contain seed.
Despite a clear uniform structure, they differ from each other in certain ways. This is the color of the outer skin layer, the size of the fetus and its shape. Valuable nutritional qualities are due to the presence of the middle fleshy layer.
The seed protecting seed is also called the intraocular. Each of them has its own unique species drawing. For example, the bones of cherry and apricot are smooth, the peach is cut with deep grooves, and the plums seem to be rough.
Single seed is the fruit of both raspberries and mulberries. Although outwardly they look like a single fruit, in fact they are small drupes, interconnected, - fruit.
The morphological structure of the bone is a sign that determines the species affiliation of the plant. The type of fruit drupe have all members of the family Rosaceae.
Dry polyspermous fruits
Single-seeded fruits, examples of which have already been given, are less common in nature than their multi-seeded relatives. After all, if there are a lot of seeds, the plant is more likely to germinate and survive.
Dry fruits are expanding and non-expanding. The first group includes a bean that opens on two sides, and the seeds in it are attached to the valves (peas, beans, alfalfa, clover).
The pod, which looks like a bean, has a partition in the middle of the fruit, to which the seeds are attached. A kind of pod is a pod, which differs only in size. The fruit in the pod is cabbage, mustard, rapeseed, matthiol, and the pod has a shepherd’s bag, yarut, gooseberry, etc.
The box opens in different ways: with poppy and Corydalis - with cloves at the top, with bleach and plantain - with a lid, and cracking - with geranium and violet.
Leaflet is a dry multi-seeded fruit that opens on one side. It can be found in larkspur and kaluzhnitsa.
An interesting plant is peanuts. It forms flowers and fruits underground. For this, he is called peanut.
Juicy Multi-Seed Fruits
Fruits of this type also have valuable flavoring properties and are of great economic importance. Everyone knows the delicious berries of currants, blueberries, gooseberries. Their outer layer is leathery, like drupes, and the other two are juicy.
According to these signs, the berry is the fruit of a tomato - everyone's favorite tomato - and potatoes. Potato fruits are inedible and even poisonous because they contain the alkaloid solanine. This substance can cause serious poisoning of the body.
The strawberry fruit is represented by an overgrown receptacle, in the pulp of which small nuts are immersed - the seeds of strawberries or strawberries.
An apple grows not only on apple trees. This type of fetus has a leathery outer and fleshy middle layer. And the inside is represented by membranous chambers that reliably protect seeds. Such fruits have pear, quince, mountain ash.
As you can see, the fruits are diverse in structure and various characteristics. They are used for breeding valuable plants, spreading and protecting seeds. And thanks to the availability of nutrients and pleasant taste, they are a valuable food product for animals and humans.