Ferns appeared on Earth many years ago. In ancient times, forests of tree ferns could be found. To date, there are very few such large plants left. Ferns have become more decorative and indoor. They are beautiful and unpretentious, they can be used for landscape design. Plants are durable and interesting.
Legends of the fern
The fern is an unusual plant. A great many beautiful legends are associated with its appearance. According to one of them, the plant came from the goddess of love - Venus, who once dropped her hair, from which the fern grew.
The most famous legend is that of the fern blossom. It says that if on the night of Ivan Kupala you see a flower of a plant, the secret of how to find treasures will be revealed to a person. However, when studying it, it becomes clear that the legend cannot be translated into reality, since the life cycle of a fern does not have a flowering stage.
Higher and lower groups of plants
Plants are divided into higher and lower groups. They differ from each other in their habitat. Higher plants "came out" on landand spend their life cycle on the ground. These plants include ferns. Terrestrial plants have a clear division into root, stem and leaf.
However, it cannot be unequivocally said that ferns have completely moved away from the aquatic habitat, since a free-living gametophyte is involved in their reproduction process and the spermatozoa necessary for the fertilization process can only exist in the aquatic environment.
Appearance
Representatives of the order of ferns spread throughout the world. They have a different appearance of the leaves, are ecologically unpretentious, while they prefer moist soils.
A fern has a root system, stem and leaves. He has no seeds. On the inside of the leaf, below, there are spores in sporangia sacs. Fern leaves are called "fronds", they are not like the leaves of other plants. They look as if several branches were placed in one plane and attached to the stem. Their color may vary from light green to dark green.
A fern, apart from the root system, consists of frond, sorus and indusia, where sorus is a bunch of sporangia, indusia is an outgrowth resembling an umbrella that closes the sorus.
Life cycle of higher plants
Existing on Earth, each plant goes its own way. The life cycle of a fern is the movement from the birth of life to the full maturation of a plant capable of giving new life. The cycle consists of two phases: asexual and sexual. These phases determine the sequencegenerations, one occurs with the help of gametes - sexual, the second - with the help of spores - asexual.
Merging, gametes form a diploid zygote, which gives rise to a new generation, asexual. In the asexual generation, reproduction occurs with the help of spores. Haploid spores give rise to the sexual generation. One of the generations always prevails over the other and makes up most of the life cycle of the plant.
Stages in the life cycle of a fern
Several stages are necessary for the appearance of a new young sprout. The life cycle of a fern is a combination of all phases, from the birth of life to the maturity phase, when the plant is already able to give rise to a new life. The cycle is closed.
The stages of the life cycle of a fern are arranged in the following sequence:
- Dispute.
- Gametophyte (sprout).
- Eggs, sperm.
- Zygote.
- Fetus.
- Young plant.
When all the stages are completed, the young plant, having developed and strengthened, will be able to repeat this cycle for the birth of the next generation.
Asexual and sexual stages in the process of reproduction
The fern is the result of asexual generation. Consider the life cycle sequence of a fern.
In order to start a new life, an adult plant should have spore sacs on the back of the leaf, in which spores will mature. When the spores are ripe, the bag will burst and the spores will fall out of it onto the ground. UnderBy the action of the wind, they will spread in different directions and, if they fall on favorable soil, will germinate. This stage is very important, because without it the plant could not exist. As a result, a process will appear - a gametophyte - the sexual generation of the fern. Its shape is similar to a heart. This heart has thin threads below - rhizoids, with which it attaches to the soil. The growth of the fern is bisexual, there are small sacs on it: in some, eggs mature, in others, spermatozoa. Fertilization occurs with the help of water.
Since the sprout is very small and has such a peculiar shape, this contributes to the slow runoff of rainwater and its retention at the bottom. This allows the spermatozoa to swim up to the eggs and fertilize them. As a result, a new cell appears - a zygote, from which a sporophyte embryo is formed - the result of a new asexual generation. This embryo consists of a haustorium, which in its appearance resembles a stalk growing into a growth, and at first consumes from it the substances necessary for its growth. After some time, the first leaf of the embryo appears, which serves as the beginning of the development of the fern.
Thus, in the life cycle of a fern, the asexual generation predominates, which gives life to a new large and long-lived plant, and the sexual generation is small and quickly dying. However, it is necessary for fertilization.
Propagation of ferns at home
Ferns are interesting and originalplants. Therefore, they are often bred at home. In order for the life cycle of the fern to go through completely and a new young plant to turn out, it is necessary to germinate the spore. A leaf of an adult fern, on which sacs with spores appeared - brown tubercles, is cut off and placed in a paper bag. This bag is kept in a warm place for one day, shaking occasionally.
While the spores mature and fall out, prepare the mixture for planting. They take a steamed mixture of peat, greenery, sand, also add crushed charcoal there, all this is taken in equal proportions. The prepared mixture is laid out in shallow pots, pressed down and moistened.
Ripened and fallen spores are taken out of the bag and poured onto the prepared surface. Favorable conditions are created for their germination:
- Temperature regime: optimally 25 degrees Celsius.
- Maintain high humidity.
- Cover the pots with glass.
Water the pots from a spray bottle. When a sprout appears, special attention is paid to watering, since the subsequent development of the plant is possible only if there is an aquatic environment in which the egg will be fertilized.
As soon as the first leaves appear, remove the glass. Then they are given a little time to adapt to the environment and dive into cuvettes. When the leaves begin to grow a little, they are first kept in cold greenhouses, and then planted in separate pots. So get new youngplants ready to grow and develop further.
Schematically represented life cycle
During its reproduction, the plant goes through several stages. For clarity and better memorization, a schematic accompaniment of this issue is recommended. Consider the existing life cycle of a fern, the diagram of which is presented below:
1. An adult plant capable of giving new life.
2. Spores appear on fern leaves.
3. Spore sacs ripen.
4. The pouch bursts, spores fall out.
5. In favorable soil, the spore strengthens and germinates.
6. A growth is formed, which is attached to the ground with the help of rhizoidal threads.
7. The embryo contains female and male cells: archegonia and antheridia:
- The female reproductive organs contain an egg.
- Male sex organs contain sperm.
- Fertilization is possible only in a drop of rain.
- Spermatozoa swim up to the eggs and penetrate inside, fertilization occurs.
8. A fertilized egg appears - a zygote. A sporophyte is formed from the zygote - a young leaf.
9. A new young plant begins its development.
The diagram clearly shows the closed nature of the life cycle.
Economic value
The role of ferns in human life is not too great. Various forms of nephrolepis - ordinary indoorornamental plants. The fronds of some shield trees are widely used as a green component of floristic compositions. The trunks of tree ferns are used as a building material in the tropics, and in Hawaii their starchy core is eaten.
Conclusion
So, we have studied the life cycle of this plant. You became aware, for example, at what stage of the life cycle the embryo appears in ferns. These are moisture-loving plants, without water their reproduction is impossible. They have spread throughout the world, while choosing places with high humidity for their life.
There are about 10 thousand varieties of ferns in total. They are medicinal, decorative, indoor.
When a new young plant is born, the life cycle begins, which includes sexual and asexual generations. The sexual generation is a sprout, it is very small and does not live long, and the young strong long-lived plant that has appeared is an asexual generation. The life cycle of a fern is dominated by the sporophyte phase.
Thus, the main generation of the fern is asexual, while it is impossible to reproduce bypassing the sexual generation.
