The organs of plants are generative: a flower, a fruit and a seed. How do plants grow?

The organs of plants generative are a flower, a seed and a fruit. They provide the plants with sexual reproduction. In this article we will talk about each of these bodies.

Flower

A very important generative organ of flowering plants is a flower. It is a modified shortened shoot, which serves as a breeding organ not for all plants, but only for angiosperms. The generative organ of flowering plants that interests us is the formation that is on the pedicel. Color is called the expanded part of the pedicel. Here are all the parts of the flower, the main of which are pestle and stamens. They are located in the center. Stamens are a male organ, and female - a pestle. The latter usually consists of the ovary, post and stigma. In the ovary are the ovules, where the egg forms and ripens. Anthers and stamens are components of the stamen. In the anthers there is a pollen grain, where sperm are formed.

Perianth

Angiosperms are also perianth. What is it for? It is not a generative organ of angiosperms, but its leaflets protect the inner parts of the flower. Seychelles are called its outer leaves, usually green. They form a cup. Corolla is formed from internal petals. The perianth is called double if it consists of a corolla and a cup, and simple - if it is composed of the same leaves. Double is typical for roses, peas and cherries. A simple one is found in the lily of the valley and in the tulip. Perianth is necessary not only to protect the flower parts inside, but also to attract pollinators. That is why it is so often characterized by a bright color. Perianth in wind-polluted plants is often reduced. It can also be represented by films and scales (poplar, aspen, willow, birch, cereals).

Nectaries

Nectaries are special glands that have some angiosperm flowering plants in their flowers. These glands secrete an odorous sugary liquid called nectar. It is necessary to attract pollinators.

Monoecious and dioecious plants

So, to the generative organs of the plant is a flower. There are two types of flowers according to the presence of pistils and stamens. Those plants that have both, are called monoecious (cucumber, hazel, oak, corn). If pistils and stamens are represented on different plants, they are called dioecious (sea buckthorn, willow, willow, poplar).

Inflorescence

Let us now consider the inflorescence. A plant can have either numerous small or single large flowers. Small, collected together, called inflorescences. They are more visible to pollinators, and also more efficiently pollinated by wind. There are several types of inflorescences. We list them.

Types of Inflorescences

• The spike is a type that is characteristic of plants on the main axis of which there are sessile flowers (without peduncles).
• There is also a complex ear. It is formed by combining several simple (examples - rye, wheat).
• The cob is a type of inflorescence, which is characterized by a central thick axis, where sedentary flowers are found (one example is the calla).
• A brush is when the flowers are on the pedicels one by one on a common axis. Examples - bird cherry, lily of the valley (pictured above).
• There is also a type of inflorescence, like a basket. It is characteristic, in particular, for dandelion and chamomile. In this case, a large number of sessile flowers are located on a thick, saucer-shaped axis.
• The head is another interesting type. It is characteristic of him that small sessile flowers are on a spherical, shortened axis (clover).
• There is also a simple umbrella (for example, in primrose or cherry). In this case, on the main axis (truncated), the flowers are located on long identical pedicels.
• But the parsley or carrot inflorescences are represented by a whole group consisting of simple umbrellas. This type is called a complex umbrella.
• In contrast to the brush, the flap of the flowers are in the same plane. Consequently, pedicels that depart from the central axis have different lengths (pear, yarrow).
• Panicle is a complex inflorescence with several lateral branches, which consist of scutes, brushes (lilacs, oats, etc.).

Some flowers in some inflorescences consist of a single corolla. In other words, they do not have stamens and pestles. This is, for example, the structure of flowers of plants such as chamomile or sunflower (pictured above).

Sexual reproduction of plants

Plant generative organs are a flower, a fruit and a seed. In order for the seed to form, it is necessary that the pollen on the stamens move to the stigma of the pistil. In other words, it is necessary that pollination occurs. In the case when the pollen is on the stigma of the same flower, self-pollination occurs (wheat, peas, beans). But it often happens otherwise. In the case of cross pollination, the pollen of one plant located on the stamens is transferred to the stigma of the pistil of some other plant. How does it get there? How do the plants multiply? Let's figure it out.

Carriers of pollen

Dry and fine pollen can carry wind (birch, hazel, alder). Flowers of wind-pollinated plants are usually small, folded into inflorescences. They have either poorly developed or no perianth at all. Pollen can also be carried by insects. In this case, the plants are called insect-polluted. In this process, can participate and birds, and even some mammals. Usually the flowers of such plants are fragrant, bright, contain nectar. In most cases, the pollen is sticky, it has special outgrowths - hooks.

For his own purposes, a person can also carry pollen, as a result of which it passes from the stamens to the stigmas of pistils. In this case, pollination is called cross. It is used, in particular, to increase yields or obtain new varieties of plants.

Male gametophyte

Pollen grains, known to us as pollen, are a male gametophyte, which is formed in stamens. In the composition of these grains there are two cells - generative and vegetative. In the first formed sperm - male sex cells.

Female gametophyte

In the ovule, in the ovary of the pistil, a female gametophyte is formed. It is called the eight-nuclear embryo sac. This gametophyte actually represents one cell in which there are eight haploid nuclei. One of them is bigger than the others. It is called an egg and is located at the pollen man. There are also two smaller nuclei that are in the center. They are called central nuclei.

The process of fertilization

If pollen enters the stigma of the pistil, the vegetative cell begins to germinate into the pollen tubule. At the same time, she moves the generative cell to the micropyle (pollen walker). In the last two sperm they enter the embryo sac. As a result, fertilization occurs. Zygote is formed when one of the spermatozoids merges with the ovum. The seed germ then develops from it. As for the second sperm, it merges with the central nuclei (as you remember, there are two of them). This is how the triploid endosperm of the seed is formed. It accumulates nutrients. Seed rind is formed from the cover of the ovule. This process of fertilization is double. It was discovered by SG Navashin, Russian botanist, in 1898. The fruit is formed either from the overgrown wall of the ovary, or from some other parts of the flower.

The organs of plant generative include, as you can see, also the seed and the fruit. Briefly describe each of them.

Seed

The seed consists of seed peel, endosperm and fetus. Outside, it covers a protective seed peel, fairly dense. In the bud there is a root, a kidney, a stalk and cotyledons, which in the plant are the first embryonic leaves. If there is one cotyledon in the embryo, such a plant is called monocotyledonous. If there are two of them, bipartite. Nutrients are usually found in cotyledons or endosperm (a special storing tissue). In the latter case, cotyledons are practically not developed.

Fetus

This is a rather complex formation, in the creation of which, besides the pistil, some other parts of the flower can participate: the flower-root, the bases of sepals and petals. The fruit, formed from several pistils, is a composite (blackberries, raspberries).

It should be said that the shape of the fruit is very diverse. There is a different number of seeds in it. On this basis, single-seed and multi-seed fruits are isolated. This is due to the number of ovules in the ovary. There are also dry and juicy fruits.

So, we described generative plant organs. In conclusion, let's talk about how seeds and fruits spread. As for the pollen, its transfer was mentioned above.

Distribution of seeds and fruits

The generative organs of interest to us (seeds and fruits), spreading, contribute to the prosperity of species and the dispersal of plants. They can be transported independently, which is typical for such species as the yellow acacia, the touchless, the lupine, the violet, the geranium. The fruits of these plants crack after ripening and with a force eject the seeds for sufficiently long distances. This method of distribution is called autochthory.

The wind can also bear fruit. This method is called anemochory. Hydrochoria is noted if water is involved in the transfer process, ornithochory is birds, zoochory is animals. In such ways, seeds of plants that have juicy fruits are carried. On the latter often develop sticky substances or hooks (burdock, string, etc.). This promotes the spread of plants. Man also plays a significant role. Particularly noticeable is its influence on the resettlement of plants in recent times, when the connections between continents and countries have increased.

So, we talked about how the plants multiply. As you can see, this process is rather complicated. Nevertheless, it is very effective.