Diversity of angiosperms. Diversity of angiosperms
V. V. Pasechnik
Biology. Diversity of angiosperms. 6th grade
How to use the textbook
Dear friends!
This year you will continue to get acquainted with biology - the science that studies wildlife. You have a textbook in your hands that will become your guide to the diverse and amazing world living organisms. You will learn about the structural features, life processes, diversity and classification of angiosperms, as well as their role in nature and human life.
The text of the textbook is divided into chapters and paragraphs. You will find the section you need by looking at the table of contents. Read the chapter title, introductory text, and information about what you will learn and learn. This will help you understand which material you need to pay special attention to.
At the beginning of each paragraph there are questions to help you remember what you have studied previously. This will allow you to better understand and assimilate new material.
Terms and plant names to remember are printed in italics.
Carefully examine and study the illustrations, read the captions to them - this will help you better understand the content of the text.
At the end of each paragraph, on a blue background, there are basic concepts that you need not only to remember, but also to be able to explain.
You can check how well you have understood the material you read by answering the questions at the end of the paragraph. After them, tasks are given that are mandatory for everyone. This applies to the “Think” section, which will help you learn to analyze the material you have studied, and the “Tasks” section.
A necessary condition for successfully mastering biological knowledge is performing laboratory work. Laboratory work is usually performed in class, using instructions, assignments and questions for them.
The textbook also contains descriptions of seasonal observations in nature.
Useful tips
1. When preparing for homework, think about what you might need besides a textbook.
2. While reading the text, correlate it with the illustrations that are in the paragraph. Pay attention to key concepts and information highlighted in the text.
3. Think about how the material you are studying can be useful and used in your life.
4. Do own notes paragraph in a notebook or on a computer in the form of text or diagram. The summary should contain main thoughts, terms and conclusions.
5. Doing homework and when preparing your message, use additional literature and Internet resources.
6. Remember that the success of your work depends entirely on your desire, perseverance, dedication and perseverance.
We wish you success!
Chapter 1. Structure and diversity of angiosperms
Angiosperms, or Flowering plants, are a group of the most highly organized plants. Their organs are divided into vegetative and reproductive.
Vegetative(from Latin word“vegetativus” – plant) organs make up the body of the plant and carry out its main functions, including vegetative propagation. These include the root and shoot.
Reproductive, or generative(from the Latin word “generare” - to produce), organs are associated with the sexual reproduction of plants. These include a flower and a fruit with seeds.
In this chapter you will learn
About the external and internal structure of the organs of a flowering plant, about their modifications;
On the dependence of the structural features of a flowering plant on its habitat;
About the role of flowering plants in nature and human life.
You will learn
Recognize the organs of a flowering plant;
Establish a connection between the structural features of an organ and its habitat.
§ 1. Structure of seeds
1. What plants have seeds?
2. What is the role of seeds in plant life?
3. What advantages do seeds have over spores?
The life of a flowering plant begins with a seed. Plant seeds vary in shape, color, size, weight, but they all have a similar structure.
The seed consists of peel, germ and contains stock nutrients. An embryo is the rudiment of a future plant. The seed's supply of nutrients is located in a special storage tissue - endosperm(from the Greek words “endos” - inside and “sperm” - seed). In the embryo they distinguish germinal root, stalk, bud And cotyledons. Cotyledons are the first leaves of the plant embryo. Plants that have one cotyledon in the seed embryo are called monocots. Monocots include wheat, corn, onions and other plants.
In beans, peas, apple trees and many others, the seed embryos have two cotyledons. These plants are called dicotyledonous.
The seeds of many plants, such as wheat, onions, and ash, have a small embryo. Almost the entire volume of their seed is occupied by storage tissue - endosperm. In others, like apple trees and almonds, on the contrary, by the time the seed ripens, the embryo grows so much that it displaces and absorbs the endosperm, of which only a small layer of cells remains under the seed coat. In pumpkin, beans, arrowhead, chastukha, the mature seed consists only of the embryo and seed coat. In such seeds, the supply of nutrients is located in the embryonic cells, mainly in the cotyledons.
(Fig. 1). Execute laboratory work, having examined the large bean seeds.
Rice. 1. Structure of seeds of dicotyledonous plants
The structure of seeds of dicotyledonous plants
1. Examine dry and swollen bean seeds. Compare their sizes and shapes.
2. On the concave side of the seed, find a scar - the place where the seed is attached to seed stalk.
3. There is a small hole above the hem - micropyle(from the Greek words “mikros” - small and “pyle” - gate). It is clearly visible in the swollen seed. Air and water enter the seed through the micropyle.
4. Remove the shiny, thick skin. Study the embryo. Find the cotyledons, germinal root, stem, bud.
5. Draw a picture of the seed and label the names of its parts.
6. Find out which part of the bean seed contains the nutrients.
7. Using the textbook, find out in which parts of the seed other dicotyledonous plants store nutrients.
The structure of monocot seeds(Fig. 2). The seeds of monocotyledonous plants have a different structure. Let's consider it using the example of cereal seeds (wheat, rye, corn).
Rice. 2. Structure of monocot seeds
The wheat seed is covered with a golden-yellow leathery pericarp. It is so tightly fused with the seed coat that it is impossible to separate them. Therefore, it is more correct to say not the seed of wheat, but the fruit called grain.
Structure of wheat grain
1. Consider the shape and color of the wheat grain.
2. Using a dissecting needle, try to remove part of the pericarp from the swollen and dry grains. Explain why it is not removed.
3. Examine a grain cut lengthwise through a magnifying glass. Find the endosperm and embryo. Using the textbook picture, study the structure of the embryo.
4. Draw a grain of wheat and label the names of its parts.
5. Using the textbook, find out what structural features the seeds of other monocots may have.
The seeds of other monocotyledonous plants, such as onions and lilies of the valley, also have endosperm, but it surrounds the embryo and does not adhere to it on one side, as in wheat and other cereals.
In chastuha, ripe seeds do not have endosperm. A horseshoe seed consists of a thin peel and an embryo, in the cotyledon of which all the reserves accumulated during the ripening of the seed are concentrated.
So, seeds have a seed coat and an embryo. In dicotyledonous plants, the embryo contains two cotyledons, and storage nutrients are usually found either in the embryo itself or in the endosperm. The monocot embryo has only one cotyledon, and nutrients are usually found in the endosperm.
MONOCOTONS AND DICOTONS. COTYLEDON. ENDOSPERM. GERM. TESTA. FUNICLE. MICROPYLE
Questions
1. Which plants are called dicotyledons and which ones are called monocotyledons?
2. What is the structure of a bean seed?
3. Where is the supply of nutrients in the seeds of beans, ash, and almonds?
4. What is the structure of the wheat grain?
5. How is the endosperm located in different monocots?
6. How do the embryos of dicotyledonous and monocotyledonous plants differ?
Section 1. Basics of decorative dendrology
Topic 1.4. Systematics and characteristics of angiosperms.
Topic 1.4.1. Division Angiosperms
Goals:
know: general characteristics of the angiosperm department and distinctive features angiosperms from gymnosperms.
be able to: structure written material
develop: cognitive processes: attention, memory, thinking, perception.
Basic concepts and terms on the topic: flower, double fertilization, angiosperms, monocots, dicotyledons.
Topic study plan:
1. The concept of “Flowering” plants. General characteristics.
2. Taxonomy of flowering plants
Summary theoretical questions:
The concept of "flowering" plants. General characteristics.
Flowering plants, or Angiosperms(lat. Magnoliophyta, or Angiospermae from ancient Greek ἀγγεῖον - vessel, σπέρμα - seed) - department higher plants, distinctive feature which is the presence of a flower as an organ of sexual reproduction and a closed container in the ovule (and then in the seed that comes from it, which is where the name angiosperms comes from). Another significant feature of flowering plants is double fertilization.
Angiosperms apparently originated from extinct seed ferns and currently occupy a dominant position in flora. The angiosperm department unites more than 390 families, about 240 thousand species.
General characteristics of the department of angiosperms
1. Angiosperms have a flower from which the fruit develops. The ovules in flowering plants are located in the ovary of the pistil (and not openly on the scales, as in gymnosperms), so the seeds are located inside the fruit, which protects them from damage. favorable conditions.
2. Characteristic feature Flowering plants have double fertilization, which is not the case in any other group of plants.
3. In the process of evolution, flowering plants have developed various adaptations for pollination, distribution of fruits and seeds, in particular with the help of animals (this indicates that flowering plants appeared on Earth when birds, mammals, and various insects already lived on it).
5. Flowering plants differ from plants of other divisions great variety vegetative organs. Thus, in terms of the variety of leaves, flowering plants are superior to plants of all other divisions. Their leaves are very plastic, more adapted to plant life in the most different conditions(dry and wet), to perform the function of photosynthesis.
6. Great value For flowering plants to flourish and widely spread, they reproduce by both seeds and vegetative organs.
Question 1. Explain why angiosperms received such a name.
Angiosperms are a division of higher plants, the distinctive feature of which is the presence of a reproductive reproductive organ - a flower and a closed container in the ovule (and then in the seed that comes from it, which is where the name angiosperms came from).
Question 2. Using a textbook, additional literature, and Internet resources, fill out the table “Diversity of angiosperms.”
Question 3. Describe the living environment of angiosperms.
Angiosperms can live in various environments: on water, in arid deserts, in forests and meadows.
Question 4. Consider the figure “Structure of higher seed plants.” Make appropriate signatures on it.
1. Cone with ovule 1. Corolla, calyx
2. Young female cone 2. Flower
3. Young male cone 3. Leaf
4. Mature cone 4. Stem
5. Seeds 5. Root
Question 5. Write down the names of plant species:
1) growing in your area and in need of protection:
The May lily of the valley, the Geneva tenacious, and the lady's slipper need protection.
2) growing in your area, listed in the Red Book of Russia:
Such plants include cruciferous gentian, Siberian iris, wedge-shaped larkspur, northern wrestler, and musk strawberry.
3) which were saved from extinction:
The snowdrop angustifolia and the calloused lily were saved from extinction.
Question 6. Having studied the text of the paragraph and Figure 43, fill out the diagram “Life forms of plants”.
Question 7. Find out what angiosperms grow in your school area. Describe several of them by filling out the table.
It is perhaps simply impossible to list all angiosperms. Yes, and name the species that have the most important in nature and human life, it will be quite difficult. After all, these plants have long acquired great practical importance, and their representatives are known as food, industrial, ornamental and fodder crops. What characteristics does the Angiosperms department have? The general characteristics and significance of these plants will be discussed in our article. So let's get started.
Biology: department Angiosperms
All seed plants have a number of structural features that make them dominant on Earth. All of them arose in the process of evolution as a result of adaptation of organisms to changing conditions environment. Department Angiosperms, according to taxonomy, on this period has more than two hundred and fifty thousand species. While their predecessors - the Gymnosperm department - are only eight hundred.
The main characteristics of the Angiosperms department:
Presence of a flower;
Formation of the fetus;
Development of the embryo inside the seed germ;
Double fertilization;
The presence of a seed surrounded by a pericarp.
Taken together, all these characteristics determine the advantages thanks to which representatives of the Angiosperms department were able to spread across the planet, mastering the conditions of different climatic zones and belts.
Holo- and Angiosperms: similarities and differences
But let's go back to basics. All seed plants are combined into two divisions: Holo- and Angiosperms. Specimens of the first systematic group are mainly represented by plants with a predominant woody life form, with a tap root system. The foliage is represented by thin leaves - needles. Thanks to them and the presence of resin passages, which prevent the process of excessive evaporation, these plants remain evergreen throughout all seasons. But the main feature of this section is the absence of flowers, and therefore fruits. Their seeds are located openly on the scales of the cones; they are not protected by anything. Therefore, the likelihood that they will germinate is not so great, since there are not enough nutrients for this.
The Angiosperms department unites plants that produce a flower and, accordingly, a fruit. Inside this, the seeds are reliably protected from any adverse effects environment, warmed and provided with the necessary supply of nutrients.
Advantages
Angiosperms are a department of higher plants that have undoubted advantages. In addition to protecting the seed and creating favorable conditions for the development of the embryo, they also include the adaptation of seeds to dissemination. For example, maple fruits have special blades, thanks to which they are easily carried by the wind. And the poppy capsule itself cracks when ripe, spreading the seeds. The tasty fruits of fruit trees are distributed by animals that eat them and excrete undigested food residues over some distance. Gymnosperms do not have fruits. Their seeds are found in cones, which are not fruits at all. These are modified shoots that serve as a place for the formation and development of seeds. They have neither the supply of substances necessary for the development of the embryo, nor the devices for the dissemination of seeds and the settlement of plants.
Classification Features
The Angiosperms department is divided into two classes. The main feature of this division is the number of cotyledons in the seed embryo. The families of the Angiosperm department - Mono- and Dicotyledonous - have other characteristic features.
Division Angiosperms: general characteristics of Monocots
The Angiosperms department, class Monocots, includes more than 600 thousand species. The life forms in which it is represented are mainly grasses. In addition to one cotyledon in the seed embryo, representatives of this class are characterized by the presence of simple leaves with parallel, and less often, with an arcuate or pinnate type of venation. The cambium is the side of the stem and is absent in monocots. For this reason, they do not form powerful trunks. The monocot class includes several smaller systematic units - families.
Family Cereals
A characteristic feature of all cereal plants is the presence of a hollow stem. It's called a straw. Such a stem is formed due to the fact that the educational tissue is located in the nodes. Representatives of the family are wheat, rye, barley, corn, wheatgrass and other plants. One more characteristic feature cereal is an unusual flower in which the corolla is transformed into scales. The number of stamens varies from three to six, sometimes there are more. Such unusual flowers collected in inflorescences - a panicle or a complex spike. The ovary is formed by two carpels. The sessile leaves of cereals, without petioles, consist of three parts: the sheath, the ligule and the plate itself.
All cereals are very valuable food crops. Most of them are used for making cereals, flour, and baking different types of bread. One of the representatives of cereal plants is sugar cane.
and Liliaceae
A characteristic feature of representatives of this family is the presence of an underground modification of the shoot - a bulb. It contains a supply of nutrients, thanks to which these plants remain viable throughout the entire unfavorable period. Chest and leeks are typical members of the family. But lily plants also form bulbs and sometimes rhizomes. Tulip, woodland, hyacinth, lily of the valley, hazel grouse... These plants are the first sign of spring. Before the onset of the dry period, they have time to grow and bloom. Then their above-ground part dies off, and the bulb underground remains viable throughout the entire period of existence of representatives of the Liliaceae family.
Class Dicotyledons: characteristic features
We continue to consider the Angiosperms department, the classes of which are well known to everyone. By the way, Dicotyledons are the most numerous of them. They have two cotyledons in the seed embryo, a taproot system, simple or compound leaves with pinnate, palmate or arcuate venation. In the stem of dicotyledons there is a cambium - a lateral educational tissue. It determines their growth in thickness. Therefore, such plants are characterized by the following life forms: grasses, shrubs and trees. Families that belong this class, are numerous. Therefore, we will consider only a few of them.
Family Rosaceae
These are as many as three thousand species of fruit crops. Apple, pear, apricot, plum, quince, cherry, peach - these are just some of their representatives. They are easy to distinguish from others by characteristic features: A five-membered flower with many stamens and a double perianth. Inflorescences - raceme or corymb. And the main types of fruits are drupes and apples. These crops are eaten and preserved by humans, because they have valuable taste qualities.
Legume family
This systematic unit has another name - Moths. These plants wear it due to the structure of the flower, the petals of which different shapes and outwardly resemble a butterfly with folded wings. And they owe their first name to the type of fruit - the bean. It is dry and opens with two flaps along the seam. Each of them contains seeds. The family includes medicinal, oilseed, fodder, food and ornamental plants. Their typical representatives are soybeans, peas, beans, clover, licorice, acacia, peanuts and other plants.
Family Solanaceae
The most famous crops representing the Solanaceae family, in addition to the plant of the same name, are potatoes, tomato, eggplant, sweet peppers and tobacco. Their flowers are also five-membered, but the sepals and petals are fused, and the fruit types are berry or capsule. The greatest economic importance among them are vegetables and industrial crops, which include tobacco and shag. But the nightshade datura, henbane and belladonna are poisonous plants that can cause severe poisoning human body.
Brassica family
This systematic unit, called in a similar way thanks to its most typical representative, it is also known as Cruciferous. The thing is that the flower has four petals located opposite each other. Outwardly, it resembles the shape of a cross. In addition to different types of cabbage, these include relis, turnip, radish, horseradish, mustard and rapeseed.
The importance of angiosperms in nature and human life
The Department of Flowering (Angiosperms) plants is, first of all, an integral part of almost all communities, a link in the food chain, the basis of green organic mass.
Among food crops special meaning have representatives of the families Poaceae, Legumes, Rosaceae, and Cruciferae. Many plants are used to make medicines. These are licorice, marshmallow, valerian, tansy, St. John's wort, celandine. The fruits of flowering plants are rich in vitamins, especially C. These are strawberries, blueberries, viburnum, rose hips, garlic and onions.
No cultural landscape can be imagined without decorative flowering plants, among which the most common are roses, daffodils, dahlias, asters, petunias, daisies, lilies, tulips and others.
Many crops are honey-bearing. Their flowers have a pleasant aroma and sweet nectar, which attracts pollinated insects. Among such plants are different types acacia, linden, buckwheat.
But humans still have to fight with some flowering plants. These are malicious weeds: wheatgrass, quinoa, sow thistle, barnyard grass and others. There are also poisonous species. Yes, when misuse Celandine can cause severe convulsions, and Datura can cause hallucinations, lack of consciousness control and delirium.
The characteristics of the Angiosperms department indicate their high organization, which allowed them to occupy a leading position in the plant world.
