What makes gymnosperms different from angiosperms? Main differences

Gymnosperms (Latin Gymnospérmae ) and angiosperms or flowering (Latin Magnoliophyta ) are two different groups of the kingdom of plants (sub-kingdom Higher plants), appearing consistently in the evolutionary development of nature. They play an important role in the life support of the planet, making up its green cover.

Some representatives of these groups are now completely extinct and belong to the category of fossil deposits. Now on Earth there are both holo- and angiosperms. There are main differences that characterize both groups.

Origin

Origin and age - this is the main thing, how do gymnosperms differ from angiosperms. Gymnosperms are a very old group of plant organisms. They exist on Earth from the Devonian period (the Paleozoic era), this is about 370 million years ago. It is believed that they were descendants of seed ferns (Latin Pteridospermae ) - completely extinct plants, numerous imprints of which are often found in the sediments of the late Devonian and Early Cretaceous.

Flowering or angiospermous plants appeared 120-150 million years ago on the boundary of the Jurassic and Cretaceous period (Mesozoic era) and quickly occupied the dominant position on the planet. It is believed that their ancestors were ancient gymnosperms.

Variety of species and forms of life

Gymnosperms account for approximately 1,000 species that currently exist in nature. Other members of this group are completely extinct and are often found by fossil paleontologists. Forms of life - evergreen trees and shrubs, as well as rare-cast lianas. The department of gymnosperms is represented by several classes:

1. Cycadic: the cycad wilting, woolly, wolverine, etc.
2. Bennettital: Williamson, nilsonyopteris (completely extinct class).
3. Gnetovye: ephedra horsetail, mirvichia mirabilis.
4. Ginkgo: Ginkgo biloba.
5. Conifers: spruce, fir, pine, juniper, cedar, etc.

A much greater species diversity is what distinguishes angiosperms from gymnosperms. Angiosperms have about 300 thousand species - this is more than half of all plants of the planet. They exist in the form of trees, bushes, perennial and annual grasses, lianas. Their classification is very diverse and complex, namely:

• Class Monocots:

Families:

Cereals: rye, oats, wheat, etc.

Liliaceae: lily, tulip, garlic, onion, etc.

• Class Dicotyledons:

Families:

Nightshade: potatoes, tobacco, nightshade, dope, whitened, etc.

Astrological: sunflower, wormwood, dandelion, Jerusalem artichoke, etc.

Legumes: soybeans, chickpeas, peas, beans, etc.

Cruciferous: cabbage, radish, radish, turnips, etc.

Rosaceae: rose, rosehip, mountain ash, cherry, etc.

Reproductive organs

The main difference between angiosperms and gymnosperms is the organ of sexual reproduction. The first group is a flower, in the ovary of which the seeds (fruit) are formed after fertilization. It consists of stamens - male genital organs, pestle - female sexual organ (from which the fetus will develop), corolla with petals, tsvetolozha and pedicels. The flower differs in shape, color and color, depending on the plant species.

In gymnosperms this function is performed by a modified shoot - a cone, which can be male or female, which is easily judged by its size. It is on its scales that the ovules develop, and subsequently the seed is formed.

Fertilization

The process of fertilization is the key, what makes gymnosperms different from angiosperms. In gymnosperms it is quite simple. In the pollen sacs, the pollen grains are gradually maturing, which are then transferred to the female gametophyte. One sperm (male gamete) impregnates only one egg, after which a seed is formed. The process takes place in semyacchatkah or megasporangia.

In flowering plants it happens differently. Here there is a double fertilization, this is what angiosperms differ from gymnosperms. This process was briefly described by the Russian scientist S.G. Navashin in 1898. It occurs as follows: from the pollen grains, two spermatozoa germinate inside the ovary, one of them fertilizes the ovule from which the seed develops, the second - the central cell, which gives rise to the endosperm - the supply of nutrients for the embryo.

Fetal formation

After fertilization, flowering plants form fruit - what distinguishes angiosperms from gymnosperms. The formation of the fetus with the seed inside occurs by modifying the walls of the ovary. But sometimes in its formation take part perianth, stamens and calyx, it all depends on the plant species. At this time, the movement of mineral and organic substances in the plant is directed toward the fetus, which can deplete other tissues. Fruits, like the species composition of angiosperms, are characterized by a variety of forms.

Gymnosperms differ from angiosperms by the lack of fruits. Their seeds are located openly on the scales of the cones and are not protected by anything. However, they have special devices that allow them to spread over long distances.

Spread

The method of seed propagation is an important circumstance, what distinguishes gymnosperms from angiosperms. In the first group, this is the only way - through the wind. Therefore, seeds are provided with outgrowths, appendages of pterygoid form and membranous structure. Air movements are able to propagate such seeds over considerable distances, which ensures the expansion of the range of a particular plant.

In angiosperms, the methods of spreading seeds are more diverse. This occurs with the participation of wind, insects, birds, mammals, humans. Some seeds have hooks and outgrowths, capable of clinging to animal clothes or wool and so traveling long distances. Many fruits have a sweet juicy pulp, edible for humans and animals, which also ensures the spread of seeds.

The structure of conducting tissues

The device of the conducting system is what distinguishes gymnosperms from angiosperms. In older plants, the movement of water and nutrients in tissues is not intense. The liquid moves slowly along tracheids - hollow tubes with thick lignified walls and perforated septa. They are part of the xylem and provide an upward flow of fluid - from the roots to the leaves. Tracheids are clearly visible when viewed under a microscope.

Conductive system of angiosperms is more perfect. In these plants the tracheids were transformed into vessels. These are very long tubes (in some lianas they reach tens of meters), through which an increased current of liquid and nutrients is carried out. This feature of the structure contributes to a more active flow of many important physiological processes in the plant: the formation of chlorophyll, photosynthesis, respiration.

Evolutionary advantages

Gymnosperms exist on Earth much longer than angiosperms. But, despite this, they did not reach the variety of species and forms inherent in younger flowering plants. What is the difference between angiosperms and gymnosperms? What advantages have allowed them to take a dominant position in the plant world of the planet? There are several points that determined this, namely:

• The appearance of a flower attractive to insects made it possible to increase the plant's chances of pollination;
• Variety of pollination options;
• Ovary protects the ovules from possible damage;
• Double fertilization allows the seed germ to receive enough nutrition for its development;
• A juicy fruit ensures the safety of the seed inside it;
• Increasing the methods of seed propagation;
• A variety of forms of life (trees, grasses, shrubs) allows you to populate more ecological niches;
• The conducting system is strengthened by vessels, which activates many necessary physiological processes of the plant organism.

The main differences. Short summary

So, how do gymnosperms differ from angiosperms? Briefly the main differences between the representatives of both groups are presented in the table.

Evolutionary ways, such adaptations as seed protection, double fertilization, insect pollination, and a more perfect conducting system, allowed angiosperms to occupy a dominant position on the planet in the world of flora.