Organ of seed reproduction in flowering plants. How do plants grow?

The end of the Mesozoic and the Cretaceous period of the biomass development of the planet is characterized by dominance and wide dispersal of a new branch of the evolution of algae - angiosperms, or flowering plants. The causes of this phenomenon were the special adaptations available in the arsenal of the structure of this group.

Today, the flowers, seeds and fruits they give are not only an important link in the food chain of most biogeocenoses, but also a source of nutrition for people, medicinal raw materials, household materials and so on. There are more than 250 thousand angiosperms known to exist in various life forms (trees, lianas, grasses, shrubs) and inhabit almost all parts of the world, continents and continents.

Classification of angiosperms

The organ of seed reproduction in flowering plants is the flower itself. It is in its structure, appearance, and also in a number of other morphological features, that the entire Department of Angiosperms is divided into two main classes:

1. Monocotyledonous plants. There are about 63 thousand species, united in 122 families. Also the class consists of 3 thousand genera. The most common families are: Cereals, Liliaceae, Ovoid, Palm, Orchid, Osocoma, Bromeliad, Cinnamon, Pepper and others.
2. Dicotyledons. More than 190 thousand species, united in 10 000 genera and 418 families. The most common of the latter are: Cruciferae, Rosaceae, Myrtaceae, Grape, Mothy, or Bean, Nightshade, Umbrella and others.

The main differences between these classes are the structure of flowers, root system, leaves. The economic importance of all these plants is very large (vegetable and fruit crops, the production of textiles, building materials and dyes, medicines, etc.), as well as the role in nature.

Evolutionary innovations in the structure

There are several such. These are precisely the signs that allowed the Porcum seeds to settle so widely on the planet, to be so durable and adapted to habitats and climatic conditions of the environment.

1. The organ of seed reproduction in flowering plants is a flower and the fruit that forms after it. The seed is protected, covered with flesh pulp or hard skin, which gives a great advantage in the survival of species and their dispersal.
2. Variety of vegetative ways of reproduction.
3. Numerous species of pollination.
4. Adaptations of the internal structure to complex environmental conditions (drought, excessive humidity, bright sun or its lack, frost, etc.). This is an advanced conductive system, flowers, seeds, fruits, powerful rhizomes and so on.
5. Variety of life forms.
6. Reproduction of flowering plants does not depend on the presence of water.

All these features have allowed these plants to occupy the land everywhere and become leaders among the representatives of the flora.

The reproductive organ of flowering plants

The organ of seed reproduction in flowering plants is a flower, then the fruit that covers the developing seed. Features of the structure of the flower, its peculiar structural parts, methods of pollination and development - all this makes angiosperms unique champions among plants for reproductive function.

For a person, a flower is an aesthetic perfection, which you can admire, give and rejoice around, and breathe in its pleasant aroma. However, the significance of this structure in nature is quite obvious: it is the organ of seed reproduction in flowering plants. Functional significance is determined by the processes of fertilization and development of sporophyte from the seed.

The structure of the flower

The flower and fruit of any angiosperm is structurally brilliant and organic in its structure. The combination of all parts allows the plant to perform reproductive functions in full, regardless of climate and other abiotic environmental factors.

Consider the general features of the structure of the flower.

1. The stem part:

• peduncle;
• receptacle.

2. Sheet component. It is formed by sepals (most often green) and the petals forming the corolla. Its coloration can be very different, from white to dark purple.

3. The generative part. Reproductive organs providing reproduction of flowering plants. These are pistils, stamens, ovaries.

Outside, the main generative components are delimited and protected by the perianth. This structure includes:

• Calyx from sepals;
• Corolla of painted petals.

Perianth can be simple or double, depending on the type of plant. It contains a large number of different substances: essential oils, pigments (carotenoids, xanthophylls, chlorophyll, anthocyanins, anthophanies and others). It is thanks to this that the flower exudes an aroma that attracts pollinators. Corolla has different sizes and colors, which is also important for capturing insects, birds, animals.

Directly the organ of reproduction of the flowering plant consists of gynecia and androcea, under the cover of the perianth. Androcea is the totality of all the stamens that perform the function of the male reproductive organ. The structure of the stamen is simple, represented by such structures:

• Stamen thread;
• Anther of two halves connected by a communicator;
• Microsporangia - nests inside the anther, in which the process of microsporogenesis and microgametogenesis (formation of spermatozoa and microspores) is carried out.

Through the stamen filament, the anther is connected with the pedicel, the exchange of nutrients and exchange products. The resulting microspores later form a male sporophyte. Spermatozoa lead to the formation of dust particles that will take part in the fertilization and formation of the seed.

The gynecia of the flower is formed by the combination of all the pestles that make up it. This structure is important because it represents, as already mentioned, the female reproductive organ. Pestle consists of:

• Ovaries;
• A column;
• Stigma.

Ovary is the structure that forms the widest part of the pistil. From the inside, it is formed by the ovules, which participate in the formation of the pericarp. Within these structures there are processes of megasporogenesis and megametogenesis. Also in the ovary is the process of fertilization and seed formation, its development.

The column of the pistil can be of different sizes. It serves for communication between the stigma and the ovary. It differs in sterility, that is, does not participate in the sexual process.

The stigma of the pistil serves to grab dust particles that fall out of the stamen anthers. The size and shape of these parts varies, depending on the type of pollination of the plant.

Flowering plants: reproduction

A flower can contain a different number of pistils and stamens. There are species that have only stamens or only pistils - they are called masculine and feminine respectively.

What else is interesting about flowering plants? Reproduction in them can be both sexual and asexual, that is, vegetative. About sexual matters, if the reproductive parts are involved. This process is also called double fertilization.

The essence of it is as follows. After pollination of the plant, fertile (active) pollen enters the stigma of the pistil and is held there, thanks to a viscous medium and special sticky components. Then the stagnant cell begins to germinate inside the column, forming a pollen tube. It is on it to the ovary that two sperm with a haploid set of chromosomes get. Once inside the ovule, one of them merges with the egg, fully formed and ready for this process. So there is a zygote - a diploid and subsequently giving rise to seed.

The second sperm inside the ovule merges with the diploid cell located in the center. As a result, an endosperm is formed. The following processes complete the reproductive functions:

• From the integrins of the ovule, a seed peel is formed;
• The walls of the base of the pistil form a pericarp;
• Ovules form the whole seed as a whole.

The result is the development of seeds inside the fetus.

Methods of pollination

There are several main options, due to which the pollen falls on the stigma of the pistil. So, let us consider the methods of pollination of angiosperms:

1. Self-pollination - without the involvement of extraneous individuals.
2. With the help of the wind.
3. Thanks to insects, animals, birds.
4. With the help of water.
5. Artificial pollination - with the help of people.

Vegetative reproduction

The reproduction of flowers is also carried out vegetatively, that is, without the participation of sexual processes. These methods are very diverse. The essence is to use different parts of the shoot (root, leaf, stem). Some of the most common options are:

• Layering;
• Mustache;
• Vaccination;
• Roots;
• Leaf and petiole.

Most of these methods are used by people in the cultivation of vegetable and fruit and berry crops.

Seeds of angiosperms

Different plants have different seeds. The structure of this structure is similar, but the shape, composition, color can vary. In addition, plants can be single and perennial. Annuals reproduce only by seeds that mature, as a rule, by the end of summer. Thus, a new generation will appear only in the next growing season. Seeds of annual flowers are often used by people to obtain various kinds of ornamental plants. The latter include asters, esholshtsiyu, marigolds, begonias, datura, calendula, gillyflowers, cosme, miraclebis and many others.

Fruits of flowering

Flower and fruit are the most important parts of the angiosperms. They allow these plants to exist under different conditions, to be widely adapted and numerous.

Fruits of plants are distinguished by a great variety of species, their consideration, classification and significance are studied by botanists all over the world, the science of them is called carpology. The most common are berries, drupes, apple, tykvina, pomegranate, pod, bean, grain, flyer, lionfish, hesperidium and others.