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"Classes of angiosperms" - Cruciferous family. What plants are called dicots. Compositae. Exceptions to the rules. Recall the classification of plants. Family Cereals. Lily family. Venation. Plants that have one cotyledon in the embryo of the seed. Bean family. Class Monocots. Plants that have two cotyledons in the embryo. Family Compositae. Fibrous root system. The division of angiosperms into classes and families.

"Flower families" - Solomina. Family. Compositae. Shrubs. Rosaceae. Dicotyledonous. Cruciferous. Flower with simple perianth. Nightshade. Creeping clover. Representatives. Cup. Representatives of sedge. Are you familiar with these plants? Lily. Plant classes. Double perianth. Flower families.

"Methods of reproduction of angiosperms" - Canadian Elodea. Connected story. Run away. The value of vegetative propagation in human life. Ways. The importance of vegetative propagation in plant life. Shoots. Self check. Let's check each other out. breeding form. Reproduction of angiosperms. vegetative organs. Goethe. Process. vegetative reproduction. Examination. methods of vegetative reproduction.

"Characteristics of angiosperms" - Birch. Plum flowers. Psilophytes. Indians. When did the first angiosperms appear? Pollen. Name the number of species of angiosperms. What kind of leaf venation is typical for monocotyledonous plants. Cotyledon. Define a class. Class Dicotyledonous. What group of plants did angiosperms originate from? Supply of nutrients. Define the class by description. Shrubs. Cases. Leaf venation.

"Families of flowering plants" - Classification of flowering plants. The emergence of personal interest. Design department. Reticulate venation. Command number boards. Scientific laboratory. Flowers. Asparagus. Logical chain. Classes of flowering plants. Rose hip. Star hour. Mysterious field. Flowering plants. Systematization of knowledge. Lily.

"Characteristics of angiosperms" - Features of the Cruciferous family. Symbols for compiling a flower formula. The value of plants of the class Dicotyledonous. Department of Angiosperms. Reproduction of angiosperms. Ancient angiosperms. Class Dicotyledonous. plant organism. The value of plants of the class Monocots. Angiosperms (flowering) plants. Flower structure. Comparative characteristics of classes. Class Monocots.

Plants. When germinating, the cotyledons become the first embryonic leaves of the seedling. The number of cotyledons is one of the characteristic features used by botanists to classify flowering plants (angiosperms). Plants with one cotyledon are called monocots and belong to the class Liliopsida (monocots). Plants with two embryonic leaves are called dicots and belong to the class Magnoliopsida (dicots).

In the case of dicotyledonous plants whose seedling cotyledons carry out photosynthesis, the cotyledons are functionally similar to leaves. But real leaves and cotyledons are functionally different in terms of development. The cotyledons are formed during embryogenesis along with the root and shoot meristem, and are therefore present in the seed until germination. True leaves are formed after the embryonic stage (that is, after germination) from the germ of the apical meristem, which is responsible for the generation of the subsequent aerial part of the plant.

Plants with underground cotyledon development have, on average, significantly more seeds than plants with above ground cotyledon development. In addition, they are able to survive if the sprout is cut off, since the meristems of the embryo remain underground (in plants with above-ground cotyledon development, the meristems are cut off along with the sprout). The alternative is that the plant should produce either a large number of small seeds, or a smaller number of seeds that are more likely to survive.

Some related groups of plants show mixed properties of underground and aboveground development, even within the same family. Groups that contain species with both underground and above ground development include, for example, the southern hemisphere conifer family Araucariaceae, legumes (pea family), and the lily genus.

Story

Term cotyledon thought up by Marcello Malpighi. John Ray was the first botanist to discover that some plants have two cotyledons and others only one. Over time, he was the first to establish the enormous importance of this fact for taxonomy.

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Notes

An excerpt characterizing Cotyledon

Maybe in the days of grief-bad weather,
Telling her girlish dreams
Like your one-year-old girlfriend
Loved the star and you? ..
Was it raining, was there a blizzard in the field,
Late evenings with you
Knowing nothing about each other
We love our star.
She was the best in heaven
Brighter than all, brighter and clearer...
Whatever I do, wherever I am,
Never forgot about her.
Everywhere her light is radiant
Warmed my blood with hope.
Young, pristine and pure
I gave you all my love...
The star sang songs about you,
Day and night, she called me into the distance ...
And on a spring evening, in April,
Brought to your window.
I gently took you by the shoulders
And he said, without hiding a smile:
“So I didn’t wait for this meeting in vain,
My beloved star...

Mom was completely subdued by dad's poems ... And he wrote a lot of them to her and brought them to her work every day along with huge posters drawn by his own hand (dad drew superbly), which he unfolded right on her desktop, and on which , among all kinds of painted flowers, it was written in large letters: “Annushka, my little star, I love you!”. Naturally, what woman could endure this for a long time and not give up? .. They no longer parted ... Using every free minute to spend it together, as if someone could take it away from them. Together they went to the cinema, to dances (which they both loved very much), walked in the charming Alytus city park, until one fine day they decided that enough dates were enough and that it was time to take a look at life a little more seriously. They soon got married. But only my father's friend (my mother's younger brother) Jonas knew about this, since neither from my mother's side, nor from my father's relatives, this union did not cause much enthusiasm ... My mother's parents predicted for her a rich neighbor-teacher, who they really liked and, according to their understanding, my mother “suited” perfectly, and in my father’s family at that time there was no time for marriage, since grandfather was put in prison at that time, as an “accomplice of the noble” (which, for sure, they tried to “break” the stubbornly resisting dad), and my grandmother went to the hospital from a nervous shock and was very sick. Dad was left with his little brother in his arms and now had to manage the entire household alone, which was very difficult, since the Seryogins at that time lived in a large two-story house (in which I later lived), with a huge old garden around. And, of course, such an economy required good care ...
So three long months passed, and my dad and mom, already married, were still going on dates, until mom accidentally went to dad’s house one day and found a very touching picture there ... Dad stood in the kitchen in front of the stove and looked unhappy “replenished” the hopelessly growing number of pots of semolina porridge, which at that moment was cooking for his little brother. But for some reason, the "harmful" porridge for some reason became more and more, and poor dad could not understand what was happening ... Mom, struggling to hide her smile so as not to offend the unlucky "cook", rolled up her sleeves right there began to put in order all this “stagnant domestic mess”, starting with completely occupied, “porridge stuffed” pots, an indignantly hissing stove ... helplessness, and decided to immediately move to this territory, which was still completely alien and unfamiliar to her ... And although it was not very easy for her at that time either - she worked at the post office (to support herself), and in the evenings she went to occupations for passing examinations in medical school.

She, without hesitation, gave all her remaining strength to her exhausted young husband and his family. The house immediately came to life. In the kitchen, there was a stupefying smell of delicious Lithuanian "cepelins", which my father's little brother adored and, just like his father, who had been sitting on dry food for a long time, ate them literally to the "unreasonable" limit. Everything became more or less normal, except for the absence of my grandparents, about whom my poor dad worried very much, and sincerely missed them all this time. But now he already had a young beautiful wife, who, as best she could, tried to brighten up his temporary loss in every possible way, and looking at dad's smiling face, it was clear that she was doing it quite well. Dad's little brother very soon got used to his new aunt and followed her tail, hoping to get something tasty or at least a beautiful "evening story" that his mother read to him in great abundance before going to bed.
So calmly in everyday worries the days passed, and then the weeks. Grandmother, by that time, had already returned from the hospital and, to her great surprise, found a newly-baked daughter-in-law at home ... And since it was too late to change anything, they simply tried to get to know each other better, avoiding unwanted conflicts (which inevitably appear with any new, too close acquaintance). More precisely, they simply “got used to each other”, trying to honestly bypass any possible “underwater reefs” ... I was always sincerely sorry that my mother and grandmother never fell in love with each other ... They both were (or rather, mother still are) beautiful people, and I loved them both very much. But if grandmother, all her life spent together, somehow tried to adapt to her mother, then mother, on the contrary, at the end of her grandmother’s life, sometimes showed her irritation too openly, which deeply hurt me, since I was very attached to both of them and very she did not like to fall, as they say, "between two fires" or forcefully take sides. I have never been able to figure out what caused this constant "silent" war between these two wonderful women, but apparently there were some very good reasons for this, or perhaps my poor mother and grandmother were just really "incompatible" , as happens quite often with strangers living together. One way or another, it was a pity, because, in general, it was a very friendly and faithful family, in which everyone stood up for each other like a mountain, and experienced every trouble or misfortune together.

The structure of plant seeds

Outside, the seeds have a dense cover - peel(Fig. 26). It protects the seed from damage, drying, penetration of pathogens.

Rice. 26. The structure of seeds of corn (A) and beans (B): 1 - seed peel; 2 - seed input; 3 - scar; 4 - embryo; 5 - embryonic kidney; 6 - integuments of the fruit of the caryopsis; 7 - germinal root; 8 - embryonic stem; 9 - endosperm; 10 - cotyledons

In some plants, the seed coat is dense, but thin, in others it is woody, thick and very hard (for plums, almonds, grapes, etc.).

On the skin of the bean seed scar- a trace from the place of attachment of the seed to the wall of the fetus. Next to the rib is a small hole - seminiferous entrance. Water enters the seed through the seminal opening, after which the seed swells and germinates.

Inside the seed is germ new plant. In some plants (beans, pumpkins, apple trees, etc.), the embryo is large, and it can be seen if the peel is removed from the seed. In others (wheat, pepper, lily of the valley, onion, etc.), the germ is very small. These seeds contain nutrients endosperm (from the Greek endon - "inside", sperm - "seed") - a special tissue, the cells of which contain many reserve nutrients.

The endosperm is represented by large cells, completely filled with nutrients in the form of starch, proteins and various oils. All these substances serve as the first source of nutrition for the embryo during seed germination.

The embryo of a new plant in the seed has two distinct parts: germ shoot and germinal root .

The germinal shoot is represented by the germinal stem, germinal leaves and germinal bud. Germinal leaves (the first leaves of a plant that appear while still in the seed) are called cotyledons . For example, beans, pumpkins, apple trees, and cucumbers always have two large, fleshy cotyledons in their embryos, while wheat, corn, tulips, and lilies of the valley have only one cotyledon in the form of a thin plate.

Flowering plants that have a seed embryo with two cotyledons are called dicots, and with one cotyledon - monocots (Fig. 27).

Rice. 27.

Outside, the seeds have a dense cover -peel . The main function of the seed coat is to protect the seed from damage, drying out, the penetration of pathogens and from premature germination.

In some plants, the seed coat is dense but thin, in others it is woody, thick and very hard (in plums, almonds, grapes and etc.).

On the skin is scar - a trace from the place of attachment of the seed to the wall of the fetus. Next to the scar is a small hole - seminiferous entrance . Water enters the seed through the seminal opening, after which the seed swells and germinates.

The peel is difficult to remove from a dry seed. But when it collects water through the seminal inlet and swells, the peel will burst, it is easy to remove it, and then the internal structure of the seed will be revealed. Inside the seed under the skin is germ - a small new plant.

Some plants (beans, pumpkin, apple tree etc.) the embryo is large and can be seen if the peel is removed from the seed. Other's ( pepper, tricolor violet, lily of the valley, onion etc.) the embryo is very small, it lies in the seed, surrounded endosperm (from Greek. endon- "inside", sperm- "seed") - special cells that contain many reserve nutrients. In such seeds, the peel does not surround the embryo, but the endosperm, inside which the plant embryo is located.

Endosperm is the storage tissue of the seed.

The embryo of a new plant in the seed has two distinct parts: the germinal the escape and germinal root .

The germinal shoot is represented by the germinal stem, cotyledons (first leaves) and germinal kidney . For example, at beans, pumpkins, apple trees and cucumber in the embryo there are always two large fleshy cotyledons, and in wheat, corn, tulip and lily of the valley- only one cotyledon.

Flowering plants that have a seed embryo from one cotyledon are called monocots , and with two dicot .

Seeds of monocotyledonous and dicotyledonous plants, having received water through the seminal inlet, swell and germinate. At the same time, the germinal root comes out of the seed through breaks in the peel. It quickly grows down, outpacing the growth of other organs of the embryo, and fixes the young plant in the soil. Then the embryonic shoot begins to grow upward. Its stem part elongates and carries up the cotyledons and the apical bud. From it then develops elevated escape with real green leaves. When the seed germinates, a young plant appears - a seedling. All seeds swell from water - both living and non-living, which have lost their germination.

A seedling grows only from seeds with a living embryo.

The sprout of any seed plant consists of main root and main shoot . They are called the main ones because they developed from the germinal root and germinal shoot.

Later, the main root branches. The totality of all the roots of a plant is called root system (a system is a whole, consisting of interconnected parts).

Cotyledon (Latin сytyledónis, cotylédon) - the inner part of the seed - a segment that contains the germ of the leaves. The cotyledon is designed to store and consume the nutrients necessary for the development of the plant, and after germination, it takes part in photosynthesis for further growth. During germination, the cotyledons turn into the first embryonic leaves of the plant. A characteristic feature of the cotyledons is their number, used by botanists to classify angiosperms (flowering) plants. Angiosperms that have one cotyledon are called monocots and belong to the class Liliopsida. Plants with two embryonic leaves are dicots and are included in the class Magnoliopsida.

Functions

In dicotyledonous plants, the cotyledons carry out photosynthesis after germination and are functionally similar to leaves. But in terms of development, true leaves and cotyledons are functionally different. In the process of embryogenesis, the cotyledons are formed simultaneously with the root system and the shoot meristem and are present in the seed until germination begins. True leaves are formed after germination from the germ part of the apical meristem, which is responsible for the generation of the aboveground part of the plant.

In cereals and other monocots, the cotyledon is a highly modified leaf that consists of a scutellum and a coleoptile. The shield itself is a tissue in the seed that specializes in absorbing and storing food from the nearby endosperm, and the cap-shaped coleoptile covers the feather (the precursor of the stem and leaves) and protects it.

Characteristics of monocots and dicots

Monocotyledonous plants have one cotyledon, leaves have parallel veins, fibrous roots, soft trunk, the number of petals is a multiple of three. Dicotyledonous plants have two cotyledons, a network of veins on the leaves, taproots, a solid trunk, the number of petals is a multiple of 4 or 5.

Gymnosperms also have cotyledons, their number is variable (multi-cotyledons) from 2 to 24 cotyledons, they form curls in the upper parts of the hypocotyl (embryonic stem), covering the feather. In each species, there are often still changes in the number of cotyledons, for example, seedlings of radiata pine have five to nine, Geoffrey pine - 7-13, and cypress always has only two cotyledons.

Cotyledons are usually short-lived. After germination, they live only a few days and die. They can be permanent, existing on the plant for a long time. Cotyledons carry food reserves, and in gymnosperms and monocotyledonous plants, reserves of other parts of the seed are available to them. Using these reserves, the cotyledons can photosynthesise and turn green, and eventually wither as the first true leaves begin to photosynthesise to feed the plant.

Cotyledons are ground or underground. Terrestrial are involved in the germination of the seed and the shedding of the seed coat. They rise above the soil and can perform photosynthesis. Underground cotyledons do not take part in germination, remain underground and do not perform photosynthesis. They have the role of a storage organ, for example, in many nuts and acorns. Plants with underground cotyledon development have more seeds than plants with above ground cotyledons. In addition, these plants can survive if their sprout is cut off, since the meristems of the embryo are preserved underground, and in plants with above-ground cotyledon development, survival is reduced to zero, because both the meristems and the sprout are cut. Therefore, such plants must produce more small seeds to reproduce the genus.