Flowering plants (also called angiosperms) are the main group within the land plants forming an independent phylum of plants called the phylum Magnoliophyta or the phylum Angiosperms. This group makes up one of two groups found in Spermatophyt seed plants : Seed plants encase their seeds in a true fruit . Thus, they bear the reproductive organs within a structure called the flower . The ovule is usually enclosed within the carpel , which in turn will give rise to the fruit after pollination has occurred.
The plants of this section are also known as angiosperm plants, so that their seeds are inside special closed structures known as fruits. The flowering plants are the most delicate plants that exist today and are characterized by their formation of clear flowers, and that the large germinal leaves, which are known in this case as carpels , have folded and their edges are stuck longitudinally. The ovules are located inside a part of the carpel or the carpel known as the ovary. After fertilization, the ovules turn into seeds, and the wall of the ovary becomes the wall of the fruit.
Angiosperms bear flowers that produce male reproductive organs called stamens and female reproductive organs called pistils . The stamens produce pollen grains that carry the zygote (male cells) to the pistils. The pistils contain structures called ovules that become seeds after pollination by organisms. The egg turns into a fruit that may be hard and dry, like a nut, or soft and fleshy, like a blackberry . Angiosperms are one of two groups of sessile seeds. The second group, gymnosperms, does not bear flowers or fruits. Gymnosperms include needle-leaved trees , such as pine and cedar .
About three-quarters of angiosperm species are dicotyledons. Dicotyledonous seeds have two thin leaves called cotyledons. The other types of angiosperms are. Cotyledonous. It produces seeds that have one cotyledon.
flower morphology
They are the organs of the plant that contain the organs of sexual reproduction, and the flower is a short stem modified for sexual reproduction and bears specialized leaves. The flower may be terminal, arising from the unfolding of a terminal bud, or it may be axillary, arising from the unfolding of an axillary bud . The axillary flower originates in the axil of a leaf called the bract. The cannabis may resemble the ordinary leaves of the plant, or it may differ from them in shape, and it is usually green, as in the flower of the delphinium plant, and it may be colored, as in the flowers of the bougainvillea plant , or it may be absent, as in the mantur . Template:Book of the plant kingdom
The flower is composed of a cylindrical pedicel, which swells at the end, forming a receptacle. The neck may bear small leaves known as bracteoles , and their number is usually two in dicotyledons and one in monocots. The neck may be long, as in the mantur, or short, as in the seven-palate, or it may be absent, so the flower is called a sessile, as in the gladiolus .
takh receptacle
It is the swollen part above the neck of the flower that bears the floral leaves. The takht is usually very short, and its knots are very close. It is difficult to distinguish the internodes in most flowers, and sometimes the stamens in the internodes between the calyx and the stamens are elongated, forming what is called the anthophore , as in some flowers of the pink family . The bed may swell to a large extent, as in strawberry blossoms.
Many flowers contain nectar glands , which are specialized glands for the secretion of nectar. Nectar is a sugary solution that has an aromatic smell. Usually the nectar glands are found on certain parts of the flower that differ according to the flowers. They may be found on a disc below the ovary, as in citrus fruits, and may be found in the wall of the ovary itself, as in some flowers of the lily family , or on the ovary, as in flowers of the lily family . Apical , and it may be located below the stamens, as in the mantour, or on the lower part of the petals, as in the flower of the sister . The nectar is usually secreted in large quantities and may be secreted in special places such as the pockets in the lower part of the lateral sepals of the flower of the mantaur , or in the spur of the violet flower .
floral oceans
On the bed of the ideal flower there are four floral perianths, two outer periphery, the calyx and the corolla, which do not enter directly into the processes of pollination and fertilization, therefore they are considered non-essential periphery and may be called the floral envelope, and two inner periphery are the pollen and pistil, which directly enter the process of pollination and fertilization, therefore they are considered essential periphery.
Calyx calyx
It is the outer perianth of the flower. It consists of small green leaves, usually called sepals . The sepals may be colored, as in the flowers of salvia and delphinium. The sepals may be loose, aposepaly, as in the flowers of the anther, or they may be fused, as in the flowers of the cotton . The calyx may fall early after the flower bud opens, as in the poppy flower , and may persist with the fruit, as in the eggplant flower. The calyx may not exist, but it is replaced by hairs or villi, as in some flowers of the compound family plants, and it may be in the form of two membranous scales, as in the sunflower .
The main function of the sepals is to protect the other floral parts in the flower bud and when the flower begins to open. The sepals may have other functions that differ according to the flowers. Colorful sepals, as in salvia, serve to attract insects, and the base of the cup may grow to be a case that contains the fruit inside it after fertilization, as in Hyoscyamus , and the villous or hairy cup may help the spread of fruits , as in some plants of the compound family.
In some flowers, there is a fifth perianth outside the calyx known as the epicalyx, as in cotton and strawberry flowers.
Coronet
It is the circumference that follows the cup to the inside and is composed of several colored leaves usually known as petals , and their number is equal to the number of sepals in most flowers , and the sepals alternate with them.
The species has many forms, it may be cruciform, as in the mantur, as it consists of four petals arranged on two perpendicular axes, and the corolla may be brushy, as in the pea , and may be labial, as in the labial family, or radial, as in the outer flowers of the sunflower inflorescence. Or tubular, as in the inner flowers of the sunflower inflorescence, or funnel-shaped, as in the petunia flower, and round, where the corolla tube is short, and its upper part is round and flattened, as in the tomato .
The main function of the corolla is to attract insects with its bright colors, and thus works to complete the pollination process, and the corolla protects the basic periphery of the flower from external influences.
In most monocotyledonous plants, the two non-basic perianths are similar, consisting of colored or non-coloured leaves. The two perianths are known in this case as the perianth, and its leaves are known as the tepals.
pollen androecium
It is the male member of the flower and is found inside the circumference of the corolla, and its leaves are known as stamens, and their number may equal the number of petals and alternate with them. In some cases, the stamens alternate with the circumference of the cup and meet with the petals. The stamens are usually loose apoandry as in the mantaur, but in some cases the stamens are synandry fused, the fusion may occur in the anther as in the flowers of the compound family. The stamens emerge from the petals, but in some cases the stamens emerge from the petals, and the stamens in this case are described as epipetalous .
The stamen consists of a filament that bears the anther at its end, and the filaments of the stamens may be branched, as in exit flowers, or they may be absent, as in some flowers of the taro family . The anther usually consists of two lobes. It may consist of one lobe, as in the hibiscus family. The two lobes of the anther are connected by a narrow tissue usually known as the connective tissue . The junction may be enlarged, as in the olive tree , or elongated, as in the salvia. Each lobe of the anther contains two pollen sacs. The anther opens by slitting longitudinally or by perforation.
The ways of attaching the thread to the anther differ according to the flowers. The thread may connect to the back of the anther along its length and is called the dorsal connection as in Magnolia , or the thread connects to the back of the anther at one point so the anther vibrates easily due to the wind and it is called the moving connection as in the flowers of the Poaceae family , or the thread connects to the base of the anther. Basal connection as in the brother.
Some flowers do not contain a perianth of pollen and are known as female flowers. The function of the stamens is to form pollen.
Gynoecium bagasse
It is the female organ of the flower and is the inner circumference, and its units are called carpels. The carpels are usually syncarpy, as in the flowers of the mallow family, and the carpels may be separate, apocarpy, as in the strawberry flower.
The carpel consists of an ovary , a style, and a stigma . The ovary is the swollen basal part of the carpel, and in the case of fusion of the carpels, the swollen basal part of the fused carpels forms a single ovary surmounted by the stigma and stigma. Fusion of carpels may occur in the ovary only, and the pens and stigmas remain loose, as in flax flower , or fusion occurs in the ovary and pen, and the stigmas remain loose, as in pelargonium , or fusion occurs in the ovary, pen, and stigma, as in citrus fruits. In the first two cases of fusion, the number of carpels is indicated by the number of pens or stigmas. bulk.
The shape of the stigma varies, as it may be spherical or discoid, smooth and sticky, and it may be hairy, or it may be feathery or with bumps.
Some flowers do not contain a perianth and are known as male flowers. The function of the stigmas is to form eggs inside the ovaries and receive pollen grains on the stigmas, where they germinate and grow inside the pen, thus helping fertilization to occur and the formation of seeds and fruits .
Place the floral oceans on the takht
The flowers differ in the level from which the floral leaves emerge on the trunk, and there are three modes for this as follows: 1- Hypogynous lower flower : in which the trunk is convex or conical and carries the stems on its top, and the rest of the floral perianths are below it, and therefore the stems are described as superior, as in flowers The nightshade family. 2- Epigynous upper flower : in which the sepals are concave and adherent and completely surround the ovary, and the other floral perianths emerge at a level of the sepals that is above the level of the annulus exit, and therefore the sepals are described as inferior as in the flowers of the sub-family. 3- Perigynous peripheral flower : in which the stalk is concave, slightly or a lot, but it does not stick to the ovary, as in the flowers of the leguminous family and roses .
reproduction
Expose the sexual organs
A flower is a branch of a modified plant that bears floral leaves on its nodes. The meristematic cells present at the apex of the stalk are gradually reduced until they are completely transformed into adult cells. Usually, the perianths are formed by the floral bud in an apical succession, i.e. the calyx appears first, followed by the corolla, then the apical, then the pistil.
The anthers reveal
The anther is formed as a small bump with four corners at the end of the thread. The bump consists of epidermis on the outside followed by parenchymal tissue on the inside, and there is a vascular bundle close to the center. In each corner of the anther under the epidermis there is one or more longitudinal rows of archesporium cells. The meristematic cell is characterized by its large size, abundant protoplasm , and large nucleus . Each of the meristematic cells divides by a wall parallel to the surface, so two layers of cells are formed, the outer ones being the primary parietal cells and the inner ones being the primary sporogenous cells. The primary parietal cells divide into several divisions with walls parallel to the outer surface forming the wall of the pollen sac (the wall of the small germ sac). The germ cells divide into several divisions, then the intermediate plates dissolve to form the mother cells pollen grains. During this, the cells of the pollen sac wall divide with vertical and oblique walls on the outer surface of the anther lobes in order to completely surround the mother cells of the pollen grains. Each cell of the mother cells of the pollen grain divides meiotically to form a group of four tetrad cells, each of which separates to become a pollen grain.
A transverse section of a mature anther , we find that it consists of two lobes connected by a junction, and in each season there are two pollen sacs, and each sac consists of a wall surrounding the pollen grains. The pollen sac wall consists of three layers, the outer layer is known as the fibrous layer, the middle layer is known as the middle layer, and the inner layer is known as the nutritive tissue layer . The nutrient layer is consumed during pollen formation and growth. The pollen grain, when small, contains a large middle succulent vacuole. Upon maturity, the nucleus becomes larger, and the cytoplasm becomes denser, increases in size, and occupies the place of the succulent vacuole. The mature pollen grain contains a large amount of starch, but in some plants the pollen grain contains fatty substances instead of starch.
Pollen grain has two walls, pollen grains have holes for germination. In the places of germination holes, there is no outer wall, and sometimes the inner layer is present in the outer wall. As for the inner wall, it becomes thicker and usually contains callus in these places.
The pollen grain contains a single nucleus with a single chromosomal basis. It usually divides before its release to form two cells that are not separated by a wall. A large cell is the vegetative cell known as a tube cell, and a small cell is a generative cell . The generative cell separates from the wall of the pollen grain and remains in the cytoplasm of the vegetative cell. Its shape becomes oval or lenticular. The generative cell divides to form two male gametes. The gamete is usually a cell without a wall and may consist of a nucleus only. Sometimes this happens before the opening of the anther, and sometimes it only occurs when germination and the formation of the pollen tube. Thus, we find that the male gamete plant has been reduced to two male gametes and a vegetative cell that has a tubular nucleus.
When the pollen grain germinates, the inner wall is absorbed with water and increases in size. The inner layer of the outer wall is torn, if any, and the inner wall emerges in the form of a pollen tube. During this, the starch in the pollen grain decomposes, and the osmotic pressure in the pollen tube rises.
The shape of pollen grains varies according to plants, as they are spherical, oval, polygonal, and oblong. The sizes of pollen grains also vary greatly, as well as the shape of the bumps on the outer wall. The number of germination holes varies. Pollen grains in monocotyledonous plants usually contain one hole, while pollen grains in dicotyledonous plants usually contain three or more holes.
After the anther is completely mature, its sacs begin to open, so the fibrous layer loses some of its water, and the outer wall of each of its cells becomes wrinkled. The cells of this layer are thick in the inner and outer walls, and have thin outer walls. Therefore, the outer walls are the most affected by the loss of water, and are the most bent inward. As a result of the desiccation of all the cells of the fibrous layer of the pollen sacs, the anther opens, and the anther opens in the area of its thin-walled cells. In many plants, the anther opens in the form of a long slit or in the form of holes or shutters .
reveal the eggs
The ovules arise inside the ovary , and the place where the egg leaves the ovary wall is called the placenta . A cylindrical growth usually extends from the placenta, known as the funicle, to carry the egg at its end. The body of the ovum is known as the nucellus, and it consists in principle of similar parenchyma cells. Then the nucellus is enclosed in one or two envelopes that surround it completely, except in a terminal part where a narrow opening called the micropyle remains. The covers work to preserve and protect the neocell, as well as provide it with the necessary food. The part corresponding to the hilum below the nacelle is called chalaza .
In an early stage of neocell formation, a cell grows under the epidermis at the apex of the neocell tissue and opposite the hilum, and the nucleus of that cell enlarges and its cytoplasm thickens.
The outer three cells dissolve and the inner ones remain, which increase in size and are known as the megaspore. The large germ grows by feeding on the three dissolved cells and the neocell tissue, and becomes the embryo sac. The nucleus of the embryonic sac is divided indirectly into two nuclei. Each nucleus heads towards one of the two poles of the cell, then each nucleus divides indirectly twice to form four nuclei with a single chromosomal basis. A nucleus from each group moves to the center of the embryonic sac. Thus, the embryonic sac has eight nuclei, three at each pole and two at the centre. The embryonic sac with eight nuclei is the female gametophyte . Each of the three nuclei located on the side of the hilum is surrounded by a part of the cytoplasm, and thus each of them becomes a naked cell, the middle one is larger in size and is slightly inward, known as the egg, and the other two cells are adjacent to the wall of the embryonic sac and are known as the two auxiliary cells, synergid cells. The three nuclei on the chalaza side are surrounded by cytoplasm and become cells known as antipodal cells, which are usually without walls. The two nuclei located in the center of the embryonic sac, which are known as the polar nuclei, unite to form one nucleus with two chromosomal bases known as the endosperm nucleus .
Types of eggs
There are different types of eggs that differ in the degree of regularity of the shape of the egg and in its position in relation to the umbilical cord. Among the most important types are the following. 1- Orthotropous straight: in which the ovum is single-symmetrical and the opening of the hilum is far from the placenta and the hilum is towards the placenta, meaning that the hilum, hilum, umbilical cord and placenta are on one straight line, as in sorrel . 2- Anatropous reflex: in which the ovum is single in symmetry, but its position is reversed, so the chloasma is far from the placenta and the hilum is towards the placenta. As in most flowering plants, including exit . 3- Horizontal Amphitropous: in which the ovum is single in symmetry, but it is partially inverted, so it is perpendicular to the umbilical cord, as in the tongue of the lamb . 4- Campylotropous renal: in which the ovule is asymmetrical and renal in shape, and the hilum and chalaza become close together, as in fava beans and peas.
Placentation
The placental position is how the eggs attach to the ovarian wall. The well-known placental conditions are: 1- Marginal placental placenta : in which the ovary is formed from one carpel, and the eggs are released from the central suture, i.e. from the place of fusion of the two edges of the carpel , as in the leguminous family . 2- Placental-basal placement : in which the ovary consists of one or more carpels, and usually one egg comes out of the base of the ovary, or more than one, as in the flower of the sunflower . 3- Apical placental placement: in which the ovary consists of one or more carpels, and usually one egg comes out from the apex of the ovary, and sometimes more, as in the flowers of the ampelaceae family . 4- Parietal placental placenta: in which the ovary consists of more than one carpel whose edges have fused together to form an ovary with one chamber, and the ovules come out from the place where the edges of the carpels adhere, and the number of rows of choroids is equal to the number of carpels, as in the flowers of the cruciferous family . 5- Axial placental placement: in which the ovary consists of more than one carpel whose edges are fused in the center of the ovary, and thus it is divided into chambers whose number is equal to the number of carpels . 6- Central placental position : It is similar to the axial placental position, except that the edges of the carpals are torn and a medial axis remains that connects the ovaries from top to bottom, and the eggs come out from the medial axis, as in the clove . 7- Free central placental position : in which the ovary consists of more than one carpel that is not divided into chambers, and a central axis grows from the base of the ovary to the top and does not reach the apex of the ovary, and the axis consists of part of the carpel and part of the neck or epithelium of the flower. The central axis bears the ovules on its surface, as in the primrose .
Pollination and fertilization
Pollination
Pollination is the transfer of pollen from the anther to the stigma . Pollination may be self pollination or cross pollination. Self pollination is the transfer of pollen grains from the anther of a flower to the stigma of the same flower or another flower on the same plant. As for cross pollination, it is the transfer of pollen grains from the anther of a flower to the stigma of another flower on another plant of the same variety or species, or of another related species, or of another compatible genus with it.
The reasons for the occurrence of cross-pollination are due to many reasons, the most important of which are the following: 1- Flowers are unisexual and the plant is dioecious , meaning that the male flowers are borne on one plant and the female flowers are borne on another plant, as in palm trees . 2- The different lengths of the stamens and styluses in the same flower make it difficult for pollen grains to transfer from the anther to the stigma of the same flower, as in the Viola tricolor flower, where the level of the stigma is higher than the level of the anther. 3- The different dates of ripening of the stigmas and the anthers are dichogamy. If the anthers ripen first, they are called protandrous, which is the most common, as in sunflowers. If the stigmas ripen first, the flowers are called protogynous , as in the pear . 4- The presence of self-sterility in flowers, i.e. the inability of the pollen of a flower to fertilize the ovules of the same flower. The occurrence of incompatibility is due to genetic factors in each of the pollen grains and eggs, which results in slow growth of the pollen tube or its non-formation at all, as in varieties of smoke, plums, and cherries. Therefore, it is good to plant different varieties of these crops next to each other to obtain a bountiful crop.
Cross-pollination occurs in several ways, the most important of which are the following: 1- Entomophily : Insect-pollinated flowers have special characteristics that attract pollinating insects . Aromatic characteristic, usually to attract insects, as in citrus fruits, and may have special shapes that enable the adhesion of pollen and stigmas to the body of the insect, as in salvia flower. Flowers that are pollinated by insects usually have pollen grains in relatively small quantities, and the pollen grains are sticky, their surfaces are not smooth, and they have bumps that facilitate their sticking to the body of the insect, and the stigmas are sticky.
Insects visit flowers to feed on pollen or nectar or both, and for this reason the flowers of some plants produce pollen grains in large quantities so that when feeding the insect, a quantity of pollen remains on it to pollinate other flowers, as in the flowers of Cassia. Among the most important insects that pollinate bees, wasps and butterflies.
2- Anemophily : These plants usually lack floral characteristics that attract insects, such as the colored floral covering, nectar glands, and the attractive smell of insects. These flowers are often unisexual and the plant is dioecious, both of which are far from the other. Hence, such flowers produce pollen grains in large numbers as a result of an increase in the number of anthers, or an increase in the number of pollen grains in the anthers, to compensate for the loss of pollen grains. The stigmas are usually feathery, easily picking up pollen from the air, and the stamens are drooping and movable to move with the slightest wind to disperse pollen. Pollen grains are light, smooth, dry, and are found singly, not in aggregates.
Some flowers that are pollinated by insects can be pollinated by the wind if the insect pollination does not succeed, as in the flower of the Cyclamen, which is ready for insect pollination.
4- Hydrophily pollination by water : Pollination occurs in aquatic plants in different ways. If the plants or their flowers float on water, pollination may occur by insects or wind, or it may occur with water, where the pollen grains have a density less than the density of water, so they float on the surface, as in the flowers of Ruppia. If the flowers of plants are immersed in water, as in many plants of the Potamogetonaceae family , then pollination takes place with water, and the density of pollen grains is equal to the density of water, and the plants in this case produce large amounts of pollen that are waxy, smooth, light, and may be threadlike. large and branched.
4- Human pollination : It is known as artificial pollination , and it occurs when a person wants to obtain a bountiful crop or plants with excellent characteristics, so he resorts to cross- breeding between corn strains to obtain seeds with abundant production. He may resort to crossbreeding and breeding in cotton to obtain desirable traits, and resort to pollination of date palms because the male plants are far from the female plants to ensure a bountiful crop.
5- Pollination with different animals : Birds , bats and slugs pollinate the flowers of some plants in special cases.
Fertilization
Fertilization is the fusion of the male gametophyte nucleus with the egg nucleus, and fertilization precedes fertilization. After a pollen grain falls on the stigma of a flower, the pollen grain germinates, and the stigma often secretes a solution that may be sugary, which helps germinate the pollen grain. When the pollen grain germinates, its inner wall expands through a germination hole, forming a pollen tube. It was believed that the nucleus of the tube passes first, followed by the passage of the two male gametes, but the opposite was found in some cases. It was found that the two male gametes do not move according to the smooth movement of the cytoplasm in the pollen tube, but rather they move independently of the movement of the cytoplasm of the pollen tube . With the growth of the pollen tube, the cytoplasm is concentrated in the terminal part of the tube, which is separated from the other part of the tube by a septum of callous material , which consists of From time to time by protoplasts, the adult long pollen tube may therefore have a number of callosal septa.
The pollen tube penetrates the stigma and is assisted by the structure of the hollow or mucous stigma. Then the pollen tube penetrates the tissues of the pen, and this is done through the spaces between the cells or through the secretion of enzymes that dissolve the cells that the pollen tube penetrates. During the growth of the pollen tube, it feeds on the food stored in it, in addition to the nutrients it derives from the tissues of the stigma and pen. It is believed that determining the direction of growth of the pollen tube penetrating the tissues of the stigma, pen, and then the ovary is due to the presence of chemical attraction. In some plants, the ovule produces threads from the hilum region to the bottom of the pen, which may have a role in directing the pollen tube to the ovule. When the pollen tube reaches the ovule, it usually penetrates through the hilum. In a few cases, penetration occurs through the chalaza in casuarina and hazelnut , and rarely through the ovule covers.
The neocell tube penetrates the wall of the embryonic sac, and in the meantime the terminal part of the pollen tube disappears and the nucleus of the tube disappears if it is still present (Fig. 91). The two male gametes pass into the embryonic sac and one of them heads to the egg cell. It is believed that the two auxiliary cells play a role in guiding and guiding the tube The pollen on the side of the egg. The gametophyte, the second note, heads toward the primary endosperm nucleus. The first male gamete fuses with the egg cell, and their nuclei unite, forming a diploid chromosomal zygote. The second male gamete fuses with the primary endosperm nucleus of the two-chromosomal base to form the endosperm nucieus with the triple-chromosomal base. In the meantime, the auxiliary and seminal cells disappear, and fertilization is known in this case as double fertilization.
reveal the fetus
After complete fertilization, both the nucleus of the endosperm and the zygote divide, and the division of the nucleus of the endosperm usually precedes the division of the zygote. The zygote divides by a transverse wall, and two cells are formed that are unequal in size. The large cell is on the side of the hilum and does not enter into the formation of the embryo. It is called the basal cell. The small cell is far from the hilum and is called the embryo cell. The base cell divides into many divisions, a row of cells known as the suspensor that pushes the embryo cell further into the embryonic sac. The embryo cell divides to form an embryo. The embryo feeds on the endosperm as it unfolds. The steps of revealing the last embryo in monocotyledons differ from those in dicotyledons. In dicotyledons, the feather is found between the two cotyledons, while in monocotyledons, the feather is found on one of its sides.
Formation of the endosperm
The endosperm divides very quickly, usually faster than the rate of division of the zygote. The embryonic sac enlarges in size and the nuclei spread within the embryonic sac. Cell walls may form separating the nuclei, thus forming endosperm cells.
Embryos differ in their consumption of endosperm food. If the growth of the fetus is slow, the endosperm is not consumed in its entirety during the development of the embryo. Therefore, the endosperm remains in the resulting seed. The resulting seed is considered endosperm, as in castor seeds and dates. When the growth of the fetus is rapid, it consumes all the endosperm food, and the mature seed is devoid of endosperm, and the seed is considered non-endospermic, as in beans and lupine seeds.
Sometimes a remnant of neocellous tissue is left in the ripe seed, known as perisperm , and the seed is called perisperm, as in the beet seed.
fruits
Fertilization is followed by a stimulation of the different ovary tissues and sometimes to some other flower tissues to form the fruits . In some cases, we find that the formation of fruits is not linked to fertilization, as in the case of bananas , girlish grapes , and navel oranges, where the fruits are formed without fertilization . These fruits do not contain seeds, and it is believed that this is due to the fact that the ovaries of the flowers of these plants contain a large amount of hormones. In many cases, it was possible to produce strawberries or tomatoes without seeds, by spraying them with certain hormones. Therefore, the process of spraying with hormones or pollen extract may lead to the formation of fruits without seeds , but fertilization is necessary to produce seeds. It is due to the activity of hormones that some tissues of the flower turn into the fruit, so that the wall of the ovary turns into the wall of the fruit, and the ovules turn into seeds, and the covers of the ovule turn into the seed palace. As the hilum of the ovule becomes the hilum of the seed. The neocellus presperm and the primary endosperm nucleus become the endosperm tissue , and the egg becomes an embryo (Fig. 94).
The fruit usually results from the disclosure of the ovary of the flower , but other parts of the flower or inflorescence may be included in the formation of the fruit, such as the fruits of apples, which are included in the formation of the flower’s stalk, and the fruits of figs, which are included in the formation of the inflorescence .
The function of the fruits is to carry the seeds , protect them, and provide them with the necessary food until they complete their growth.