Why are gymnosperms called that? Similarities, differences and characteristics: gymnosperms and angiosperms

Question 1. Why did gymnosperms get this name?
Gymnosperms got their name because their seeds lie openly (barely) on the surface of the scales of the cones, and not inside the fruit, like in angiosperms. In gymnosperms, the ovules are located openly.

Question 2. What are the main characteristics of gymnosperms? How does their structure differ from the structure of ferns?
Gymnosperms have a stem, roots and leaves. Unlike ferns, which reproduce by spores (a spore consists of a single cell), gymnosperms produce seeds (seeds are multicellular structures), through which they reproduce and spread.

Question 3. What gymnosperms do you know?
Spruce, pine, fir, larch, cedar, juniper, cypress, sequoia (most tall tree on Earth - its height can reach 120 m), etc. Among gymnosperms there are also “long-livers”: Bristlecone pine, which grows in California, can live up to 5000 years.

Question 4. Compare external structure pine and spruce. In what conditions do pine and spruce trees grow?
Scots pine is a tree that reaches 50 m in height. At the ends of the branches there are buds that give rise to new shoots. Pine shoots are of two types: elongated and shortened. On the elongated shoots there are brownish scaly leaves, from the axils of which shortened shoots develop. Each shortened shoot bears two leaves - needles. The needles live from 1.5 to 2 years, and then fall off along with the shoot. The needles are covered with a thick cuticle, they have only two non-branching vascular bundles and a few stomata, which are located in the recess, so the pine evaporates water sparingly. The structural features of the leaves allow the pine to live in relatively dry places and tolerate significant hypothermia. The unpretentiousness of pine is also explained by the structure of its root system. Pine has a tap root system. The main root penetrates deep into the soil and supplies water to the plant. When growing on shifting soils (sand), pine trees powerfully develop lateral roots that hold the plant in the ground. Pine is light-loving and can grow in poor soils and even in swamps and rocks. The thick plug of the trunk allows the pine tree to withstand not very strong fires. Pine trees in forests only have branches near the top. And in open areas the pine trees are spreading. Pine trees have male and female cones. Pine growing on sand has a deep tap root system with highly developed lateral roots; A pine tree growing in a swamp has a superficial tap root system. Pine is light-loving. It is undemanding to soil and grows on dry sandy soils, in damp wetlands, in chalk mountains and even on bare rocks, in the cracks of which it takes root. Pine seeds have a transparent wing and are spread by the wind.
The spruce tree has a pyramidal crown; short needles sit alone, remaining on the branches for 5-7 years. Spruce also produces two types of cones - male and female. The main root is poorly developed; lateral roots are located in the surface layers of the soil. Spruce is a shade-tolerant species. In a dense forest, even the lowest branches are preserved. Spruce grows well only on rich nutrients, well-moistened soil.

Question 5. Why do the lower branches of a pine tree die off in the forest, while those of a spruce tree are covered with needles?
Pine is light-loving, so its lower branches, shaded in the forest by neighboring trees, die early. Spruce is a shade-tolerant species; in a dense forest, even the lowest branches remain in good condition. Spruce is shade-tolerant and grows in rich soils. A pine tree cannot grow under a spruce canopy, but a spruce tree can grow under a pine canopy. Spruce has a superficial root system, the needles last for 6-8 years, the cork is thin, so the spruce does not tolerate even mild fires. The root systems of pine and spruce form a symbiosis with the hyphae of myceliums - mycorrhizae.

Question 6. What is the importance of gymnosperms?
The importance of gymnosperms in biocenoses is enormous, since they are forest-forming species. In the Northern Hemisphere, most of the forests are coniferous forests. Gymnosperms provide food to animals: moose feed on young pine shoots, squirrels and crossbills feed on seeds cedar pine etc. Gymnosperm wood is used by humans for various purposes (as fuel, as building material, as a raw material for paper, etc.). The bulk of wood in Russia is harvested in coniferous forests. Larch wood is particularly strong and durable, it is resistant to rotting. Using chemical treatment, artificial fibers similar to silk threads are obtained from pine wood. Paper is made from spruce wood.

1. What is a spore?
2. What role do spores play in plant life?
3. What plants are classified as lower? How do they differ from the higher ones? Which plants produce seeds?

The presence of seeds gives these plants a huge advantage over spore plants. Unlike spores, seeds have a supply of nutrients, and the embryo of the future plant, located inside the seed, is well protected from unfavorable conditions.

Rice. 75. Cypress

The leaves of most conifers are narrow, needle-shaped - the so-called needles. Some species, such as cypress, have scaly leaves.

The needles have a dense skin covered with a waxy substance, so the plants evaporate little water and are well adapted to unfavorable conditions.

Coniferous plants are widespread throughout our country.

Pine photophilous (Fig. 76). In dry pine forests(borah) it is always light. There are tall, slender trees like columns, the branches of which remain only near the tops, so they let in a lot of light. And in open areas the pine trees are spreading.

Rice. 76. Pines

Pines are unpretentious. They can be found on sands, in swamps, in chalk mountains and even on bare rocks, in the cracks of which they take root.

In pine trees growing on dense soils, the main root is well developed and goes deep. In pines growing on sandy soils, in addition to the main root, lateral roots develop near the soil surface. They spread far to the sides of the tree trunk. On swampy soils, the main root of pine trees develops poorly.

In spring, small cones of two types can be seen on young branches. Some of them, greenish-yellow, are collected in close groups at the base of young shoots. These are the so-called male cones.

Others, reddish, single, are female cones. They are found on the tops of young branches. The female cones grow and become woody. First they turn green, then brown.

After two years, seeds fall out of the cones. In most species of pine they have membranous wings, thanks to which they can be spread by the wind.

Young pine branches bear small scaly brown leaves, in the axils of which very short shoots sit. On each of these shoots, Scots pine develops two bluish-green needle-shaped leaves, that is, two needles. The needles live for 2-3 years and then fall off along with a short shoot. Therefore, the fallen needles are connected in twos.

At favorable conditions Pines reach 30-40 m in height and live up to 350-400 years.

Spruce differs from pine not only appearance(Fig. 77). Spruce is a shade-tolerant species; in a dense forest, even the lowest branches are preserved.

Rice. 77. Coniferous plants

Spruce forests in our country occupy vast areas. Twilight reigns in them, the dense crowns of trees close together here. There is no undergrowth under the trees and very few grasses. Only green mosses or a solid litter of fallen pine needles cover the soil.

Spruce grows well only in nutrient-rich, well-moistened soil. The main root of spruce is poorly developed. Lateral roots are located in the surface layers of the soil, so the wind sometimes knocks down spruce trees, uprooting them. The spruce tree has a pyramidal crown. The short and pointed needles of spruce sit alone, remaining on the branches for 5-7 years.

Spruce also produces two types of cones - male and female. Purple-red or greenish young female cones, appearing at the ends of last year's shoots, stick out vertically. Mature cones hang down, they ripen late in the fall in the first year of life. After sowing the seeds, they fall off. The spruce seed is winged. Male cones, located below the female ones, have a yellowish-brown color.

Spruce lives up to 250 years, reaching a height of 40 meters.

Larch widespread in our country, especially in Siberia (Fig. 77).

This is a very light-loving and cold-resistant breed. It can grow on dry sand, rocky and marshy soils. Larch needles are light green, soft, and do not have a dense skin. Among coniferous trees In our country, only larch sheds its needles every year. It lives up to 400-500 years, reaching 30 m in height and 2 m in diameter.

Juniper- a small tree or shrub (see Fig. 77). Grows in spruce and pine forests. The leaves are needle-shaped. The scales of female cones are fleshy, juicy, and grow together to form a cone berry that ripens for two years. Juniper grows slowly, but is very durable, living up to 2 thousand years. Currently, it has become a rarity in our forests and needs protection.

The structure of needles and conifer cones

Coniferous plants have special volatile substances- phytoncides (from the Greek words “phyton” - plant and “cido” - I kill), which suppress the development of many harmful bacteria not only in the forest, but also in its surroundings.

In the taiga of our country largest area occupied by forests of larch, then pine and spruce.

Larch wood is particularly strong and durable, it is resistant to rotting.

Pine and spruce wood is used as valuable construction and ornamental material. Using chemical treatment, artificial fibers similar to silk threads are obtained from pine wood. Paper is made from spruce wood. Gymnosperm wood is a valuable raw material for many industries.

Siberian pine is called cedar in Siberia, although real cedars grow only in the mountains North Africa, in the eastern Mediterranean and the Himalayas. Good edible cedar oil is obtained from the seeds of Siberian pine.

New concepts

Questions

1. Why did gymnosperms get this name?
2. What are the main characteristics of gymnosperms? How does their structure differ from that of ferns?
3. What gymnosperms do you know?
4. Compare the external structure of pine and spruce. In what conditions do pine and spruce trees grow?
5. Why do the lower branches of a pine tree die off in the forest, while those of a spruce tree are covered with needles?
6. What is the significance of gymnosperms?

Think

Why are many sanatoriums and holiday homes located in pine forests, are coniferous plants planted on the territory of medical institutions?

Quests for the curious

1. Determine in what months of the year the ripening and dispersal of pine and spruce seeds occurs in your area.
2. In May-June, observe the development of young shoots of pine or spruce from the buds.

   Pay attention to the location of the cones on the shoots.

   Collect pine and spruce seeds. Sow them in the school plot.

   Take care of the seedlings. Use the grown plants for landscaping.

Did you know that...

Rice. 78. Ginkgo biloba

This plant is called a living fossil, since its closest relatives became extinct tens of millions of years ago. Ginkgo biloba is a tall (up to 30 m) deciduous tree, currently growing wild only in the mountains of Western China.

Ginkgo is used for landscaping in southern cities, including in our country. Residents of Eastern countries have long consumed roasted ginkgo seeds as food. IN folk medicine A decoction of ginkgo leaves was widely used for cerebrovascular diseases. Currently medicinal properties ginkgo recognized official medicine, preparations from it can be bought in pharmacies.

Quests

Gymnosperms and angiosperms are representatives of two groups of seed plants that successively appeared on Earth and spread throughout it. Angiosperms are otherwise called flowering plants. They belong to higher plants that “acquired” a flower as an organ of sexual reproduction and a place where the ovary and then the fruit are formed. The flower of angiosperms is a key organ of generative or sexual reproduction. Double fertilization occurs in it, discovered among representatives of the group by Navashin. Its essence is that from the male gametophyte, represented by a pollen grain, 2 sperm sprout. The first fertilizes the egg - the ovule, in other words - the modified female sporangium. In this case, a zygote is formed, a totipotent cell capable of producing a new one, which has received its set of genes from both parents. The second sperm merges with polar bodies. They are “free floating” in the center of the embryo sac. After completion of the fusion-fertilization process, a primary endosperm is formed in the archegonium, which has a polyploid set of chromosomes. Most angiosperms have a triploid chromosome set. The endosperm is needed to provide the seed with nutrients coming from the mother's body. Gene imprinting also occurs here, a phenomenon in which hereditary information, carried by DNA nucleotides, is converted into a functional environment - proteins and RNA. Cytokinin hormones are also found here, stimulating cell division and the formation of the embryonic organ. The whole process occurs in angiosperms in the cavity of the ovary, the lower swollen part of the pistil of a flower. The ovary protects the ovule from drying out, temperature fluctuations and insect attacks. After the successful completion of the fertilization process, the ovary becomes a fruit, in the middle of which the seeds formed from the ovule are securely hidden. The structure of the seed embryo makes it possible to distinguish 2 classes among Angiosperms - Dicotyledons and Monocots. Popular representatives of the first are magnolias, buttercups, carnations, cabbage, honeysuckle, and bluebell. The second group included lilies, palm trees, orchids, calamus and asparagus. Gymnosperms appeared in the Paleozoic, Devonian. They are considered the ancestors of angiosperms. This group includes ginkaceae, cycads, conifers and the most advanced - oppressive, amazing plants, the seeds of which are coated. Why amazing? - Welwitschia, a stump with two leaves, vines and ephedra are prominent representatives of the class. Amazing Welwitschia (lat. Welwítschia mirábilis) The main feature of gymnosperms is the insecurity of the ovule, and subsequently the seeds. The ovary is represented by the scales of a female cone, on which one or more ovules are planted. From it a seed develops - an embryo covered with a protective seed coat. Endosperm, which accumulates nutrients, is formed from the body of the female gametophyte before the fertilization process begins.

Basic distinctive feature plants related to this species, is propagation using seeds. Gymnosperms and angiosperms belong to the general group of seed plants (spermatophytes). They represent a group of superiors. Let's consider how angiosperms differ from gymnosperms flora.

Structure and characteristics of reproduction

This division of seed plants is considered the most ancient (appeared about 350 million years ago). It is believed that they evolved from spore ferns. However, the former already have an ovule (female sporangium) and pollen grains.

Attention! Reproduction by seeds is one of the main adaptations to terrestrial existence. This is an evolutionary leap by which seed plants can reproduce without direct interaction with water, spread to large areas and increase the safety of offspring due to the supply of nutrients. I carry out plants important function, creating a blanket of the planet and highlighting large number.

Woody plants without flowering

• life forms of gymnosperms – trees and shrubs. Most of the representatives have needle-shaped leaves or scales - needles, which are covered with a cuticle. They are called evergreens. Only a small number of gymnosperms have leaves;
• reproduction occurs without interaction with the aquatic environment;
• the main part of the trunk is occupied by xylem - conductive tissue that contains tracheids and resin ducts;
• presence of resin – characteristic feature everyone life forms gymnosperms. It gives trees a special coniferous smell and has bactericidal effects, saturating the wood and preventing it from rotting;
• the reproduction process takes place with the help of the genital organs of the strobila (cones). Most often, strobili are heterosexual, located either on the same plant (they are called monoecious) or separated into different ones (dioecious). In this case, the cones differ in size and color. Females are called megastrobili, males are called microstrobilae;
• are divided into several classes: Gnetaceae (Welwitschia amazing, Melingo), Ginkgoaceae (Ginkgo biloba), Cycadaceae (cycad) and conifers (Araucaria, Agathis, pine, larch, fir).

Most often, Scots pine is chosen as an example for the propagation process. She is monoecious. Male (large with a reddish tint) and female (small, green or bluish in color) generative organs are located on the same plant.

Microstrobilus pollen is carried by the wind and reaches the megastrobilus ovules, where pollination occurs. Through pollen tubes, pollen particles penetrate to the egg cell, which is formed in the archegonium. Pollen grains produce two sperm, one of which fertilizes the egg. This is how a zygote is born. It remains surrounded by the ovule, which carries a supply of nutrients. The seed can germinate for several years inside the cone. After the required period of time, the seeds leave the shell and scatter on the surface of the earth.

Flowering plants

The department of angiosperms is the most highly developed of all representatives of the plant world. It has more than 300 thousand species and is distributed almost everywhere. The organs of angiosperms are generative (the flower responsible for reproduction) and vegetative, which provide mechanical support, transportation, the passage of photosynthesis, gas exchange, and the accumulation of nutrients.

Main characteristic features angiosperms are the following:

• life forms are represented by trees, shrubs, subshrubs and herbs (annual, biennial and perennial);
• The root system is powerful and well defined. There are fibrous and rod ones;
• O The reproductive organs of angiosperms are female (gynoecium) and male (androecium). Found inside the flower. The androecium is a united stamen, each of which includes a filament and an anther. This is where sperm maturation occurs. The gynoecium is a collection of carpels. They, in turn, consist of an ovary and an elongated column with a wide part on top - the stigma;
• The ovary is of particular importance for the development of the embryo. This closed cavity is what protects the ovule of angiosperms. It is located on the lower expanded part of the pistil and protects the rudiment from sudden changes in temperature, drying out and any other environmental influences;
• There are two classes of angiosperms: monocotyledons and dicotyledons, which differ greatly in their structure. Monocots include representatives such as gladioli, lilies, wheatgrass, and orchids. For dicotyledons: dandelion, apple tree, raspberry, crassula and many others.

Main differences

To distinguish between species it is necessary comparative characteristics gymnosperms and angiosperms. Their two departments are almost completely different from each other. For more a shining example What is the difference between gymnosperms and angiosperms, an explanatory table is presented below.

Table: Differences and similarities between angiosperms and gymnosperms

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Gymnosperms and angiosperms are representatives of two groups of seed plants that successively appeared on Earth and spread across it. Angiosperms are otherwise called Flowering plants. They belong to higher plants that “acquired” a flower as an organ of sexual reproduction and the place where the ovary and then the fruit are formed. The flower of angiosperms is a key organ of generative or sexual reproduction. Double fertilization occurs in it, discovered among representatives of the group by Navashin. Its essence is that from the male gametophyte, represented by a pollen grain, 2 sperm sprout. The first fertilizes the egg - the ovule, in other words - a modified female sporangium. In this case, a zygote is formed, a totipotent cell capable of giving birth to a new one, which has received its set of genes from both parents. The second sperm merges with polar bodies. They are “free floating” in the center of the embryo sac. After completion of the fusion-fertilization process, a primary endosperm is formed in the archegonium, which has a polyploid set of chromosomes. Most angiosperms have a triploid chromosome set. The endosperm is needed to provide the seed with nutrients coming from the mother's body. Gene imprinting also occurs here, a phenomenon in which the hereditary information carried by DNA nucleotides is converted into a functional environment - proteins and RNA. Cytokinin hormones are also found here, stimulating cell division and the formation of the embryonic organ. The whole process occurs in angiosperms in the cavity of the ovary, the lower swollen part of the pistil of a flower. The ovary protects the ovule from desiccation, temperature fluctuations and insect attacks. After the successful completion of the fertilization process, the ovary becomes a fruit, in the middle of which the seeds formed from the ovule are securely hidden. The structure of the seed embryo has made it possible to distinguish 2 classes among Angiosperms - Dicotyledons and Monocots. Popular representatives of the first are magnolias, buttercups, carnations, cabbage, honeysuckle, and bluebell. The second group included lilies, palm trees, orchids, calamus and asparagus. Gymnosperms appeared in the Paleozoic and Devonian. They are considered the ancestors of angiosperms. This group includes ginkgo, cycads, conifers and the most advanced - oppressive, amazing plants whose seeds are covered with a shell. Why amazing? – Velvichia, stump with two leaves, vines and ephedra are prominent representatives of the class. Welwitschia is amazing (lat. Welwítschia mirábilis) The main feature of gymnosperms is the insecurity of the ovule, and subsequently the seeds. The ovary is represented by the scales of a female cone, on which one or more ovules are planted. From it a seed develops - an embryo covered with a protective seed coat. Endosperm, which accumulates nutrients, is formed from the body of the female gametophyte before the fertilization process begins.
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