Alternation of generations of angiosperms. Presentation on the topic "Alternation of generations.". Simple and complex life cycles

PLANTS PRODUCTION

Lecture 22

TYPES OF PLANTS REPRODUCTION

Reproduction is a characteristic property of all living beings.

vegetative reproduction. Asexual reproduction. sexual

Reproduction. The value of the sexual process.

Generation alternation

Reproduction is a characteristic property of all living beings. Reproduction is just as necessary as growth, irritability, heredity, etc. The essence of reproduction lies in the fact that each organism reproduces auxiliary individuals for itself. Thanks to this, the existence of the species is maintained. The process of reproduction is based on the ability of cells to divide and differentiate.

As living beings are diverse, so are the methods of reproduction. But the differences relate mainly to the details of the process. According to the main fundamental features, three methods of plant reproduction are distinguished - vegetative reproduction, asexual and sexual.

Vegetative propagation. This type of reproduction is characteristic of higher and lower plants. The formation of new individuals during vegetative reproduction occurs due to vegetative organs, parts of the vegetative body.

An example of vegetative reproduction is the reproduction of some unicellular plants by dividing a cell into two daughter cells. This is how chlorella, chlorococcus, pinnularia and many others breed. unicellular algae. Vegetative propagation occurs by budding yeast. Yeast is a single-celled fungus that reproduces vegetatively very quickly, separating its smaller part from the cell. This method of reproduction is called budding.

In multicellular algae, vegetative propagation occurs by fragments of filaments or fragments of thalli (for example, in spirogyra, cladophora).

Very varied ways vegetative propagation in flowering plants. New individuals of the species develop at the expense of vegetative organs.

The roots of many plants give adventitious buds from which new shoots develop. Over time, they take root and continue to exist as independent plants. Raspberries, gooseberries, thistle, bindweed, dandelion and many other plants propagate by root cuttings and in the form of root shoots.

Leaves rarely form adnexal buds. Sometimes buds develop from fallen leaves, less often - on a plant. In the latter case, the plants are called viviparous. The core, gloxinia, certain ferns, begonia, bryophyllum, lilies, hyacinths and some other species can reproduce using leaves.

Scraps and fragments of stems - stem cuttings - in nature reproduce cacti, elodea, hornwort, duckweed, etc. Artificially, a huge number of plants reproduce by stem cuttings: apple trees, pears, willows, currants, grapes, roses, chrysanthemums, etc.

For vegetative propagation, modified shoots - tubers, bulbs, rhizomes - and mustaches and lashes are also used. In connection with this function, their morphological and anatomical structure changes.

characteristic feature vegetative reproduction is that the properties and characteristics of the mother plant are very fully and accurately reproduced in the offspring. The seed progeny of flowering plants does not always repeat the characteristics of parental forms, it is very variable and diverse. Many valuable varietal qualities are lost during seed reproduction. For this reason, vegetative propagation is widely used in agricultural practice, especially in horticulture and floriculture. Reproduction of apple trees, pears, roses by grafting is one of the options for artificial vegetative propagation.

asexual reproduction. It is characterized by the fact that specialized haploid cells, the so-called spores, are formed to reproduce offspring. Each spore, falling into favorable conditions, gives rise to a new individual.

A spore is a cell with a more or less dense shell. Its contents - cytoplasm, nucleus, mitochondria, plastids or proplastids - are the usual components of a living cell. In addition, spores contain spare nutrients- oil drops, protein crystals, starch, sugar.

controversy aquatic plants They have flagella, with the help of which they actively move in the water. Such disputes are called zoospores. Spores of terrestrial plants and some aquatic plants without flagella. They are carried by wind or water currents. They are called actual disputes or aplanospores.(from Greek a - no, pianos - travel).

Spores are formed in ordinary vegetative cells of the mother organism or in special multicellular formations - sporangia. Multicellular sporangia are characteristic of terrestrial plants. The strong walls of the sporangium protect the spores and sporogenous tissue from drying out. In algae, sporangia are simpler, since drought does not threaten these plants.

In single-celled plants, such as Chlamydomonas, spores are formed by dividing the contents of the cell into several parts. Each part of the protoplast, even inside the mother cell, is covered with its own membrane and takes shape as an independent cell. Then the shell of the mother cell is mucilaginous, the mucus is washed out by the flow of water, a hole is formed through which spores emerge. Each of them gives rise to a new chlamydomonas. The dispute is formed 4-8.

In higher plants, during the formation of spores, reduction division (meiosis) occurs, so the spores in these plants are haploid cells.

Asexual reproduction is characterized by: very high intensity of reproduction; one plant produces thousands and thousands of spores; very homogeneous offspring, all individuals of which almost repeat the signs and properties of the mother plant.

As can be seen from this characteristic, asexual and vegetative reproduction have much in common. It is in both cases that only one organism participates in the formation of offspring, and for this reason a very homogeneous, low-variable offspring is formed. These features bring together vegetative and asexual reproduction. They differ in that during asexual reproduction, special reproductive organs are formed, while this does not happen during vegetative reproduction - new individuals develop from vegetative organs. Differences, apparently, relate to details, but the main features of asexual and vegetative reproduction are common, therefore they are sometimes combined into a general type of asexual reproduction and are considered as variants of this process.

sexual reproduction . This type of reproduction differs significantly from asexual and has an important biological significance for the evolution of the species.

During the sexual process, special cells of sexual reproduction are formed - germ cells or gametes(from the Greek gametes - spouse), Unlike spores, each individual gamete cannot give rise to a new individual, this process is preceded by the process of fusion of two gametes - fertilization. The cell that is formed as a result of fertilization is called zygote(from the Greek zygo. - yoke).

Morphologically, the zygote is characterized by the fact that it has two sets of chromosomes, that is, it is diploid. The zygote is characterized by high physiological activity. After a certain period of rest or without it, it vigorously divides, and its derivatives also divide, as a result of which multicellular body. The end result of the development of the zygote is the formation of a new individual.

Gametes rarely, only in some lower plants, belong to one organism. But even in this case they are not quite identical. More often, gametes formed by different individuals copulate (merge). Morphologically, they may be the same, but they differ physiologically.

There are three forms of the sexual process. The sexual process is called isogamous (from the Greek isos - equal, gamos - marriage) if the gametes are the same. In this case, the gametes are morphologically not differentiated into male and female. Their shape and size are the same, they are mobile. The sexual process is called heterogamous (from the Greek heteros - different, gamos - marriage), if the gametes differ in size and shape, but retain mobility. Isogamy is observed, for example, in chlorococcus, cladophora, heterogamy in eudorina; both forms of the sexual process are observed in different types chlamydomonas.

In the vast majority of plants, gametes are differentiated into male and female. They differ in their size, structure and functions. The female gamete is a large, immobile cell, it retains a certain supply of nutrients. It is called an egg. Hence the name of the process oogamy (Greek oop - egg). Male gametes are very small and mobile cells, with one, two or many flagella. They are called spermatozoa (from the Greek sperma - seed, zoon - animal). Typical gametes are haploid cells. The reduction in the number of chromosomes occurs as a result of meiosis, which in animal organisms occurs directly during the formation of gametes, and in plants - in a different phase of the development cycle. When a zygote is formed, a double number of chromosomes is restored as a result of fertilization.

Gametes are formed in gametangia: female - in archegonia, male - in antheridia. The structure of these organs varies widely and is studied in the course of taxonomy of lower plants.

The value of the sexual process. Sexual reproduction is not very intense. Its meaning is different.

As a result of the sexual process, a more viable "updated" offspring is formed. The hereditary basis of the zygote is, of course, richer than that of any individual gamete or spore. Therefore, as a result of the sexual process, a more diverse, more variable and plastic offspring develops. The relative survival of sexual offspring is higher. Since individual variability is clearly manifested in it, it becomes possible to exist in relatively diverse conditions. The range of the species is expanding, new varieties are appearing. Pronounced individual variability provides rich material for natural selection. All these prerequisites ensure the biological progress of the species.

Thus, if the sexual process almost does not increase the number of species, then it improves its "quality" - increases its viability. With these results, the sexual process is fundamentally different from asexual.

With asexual reproduction, the number of individuals increases significantly, but in qualitatively there are no shifts. The signs of the maternal generation in asexual offspring are repeated almost unchanged. As you can see, the sexual and asexual processes complement each other, so most species are characterized by alternation of generations.

Generation alternation. The essence of the phenomenon lies in the fact that in the development cycle of each species, the forms of reproduction and nuclear phases alternate sequentially. If the starting point is fertilization and, consequently, the formation of a zygote, then the development cycle is as follows.

An individual develops from a zygote, which consists of diploid cells (diplont) and reproduces asexually, forming spores. On this basis, such an organism is called a sporophyte (from the Greek sporus - growth and phyton - plant). Spores are haploid cells; during their formation, a reduction in the number of chromosomes occurs. From the moment of spore formation, the haploid phase of the development cycle begins. The individual developing from the spore consists of haploid cells (haplont) and reproduces sexually, forming gametes. For this reason, the haplont is otherwise called a gametophyte (from the Greek gametes - spouse and phyton). As a result of fertilization, a zygote is formed again, and the development cycle is repeated.

In the development cycle, two key moments are distinguished, in which a change in nuclear phases occurs: meiosis, typical in the formation of spores, as a result of which the diploid phase is replaced by a haploid one, and fertilization, in which the haploid phase is replaced by a diploid one.

At different species, depending on their evolutionary advancement, the alternation of generations is carried out in different forms.

A. In many algae, only the zygote is diploid. Its first division is meiosis. Consequently, the entire vegetative life of the species takes place in the haploid phase. This life cycle is called haplontic. It is inherent in many green algae (chlamydomonas, ulotrix, spirogyra).

B. The species is represented by individuals morphologically identical, but differing cytophysiologically. Some of them are diplonts, others are haplonts. The first formed from the zygote, reproduce by spores, that is, they are sporophytes. The latter, formed from spores, reproduce sexually, forming gametes, that is, they are gametophytes. Since both generations are morphologically the same, the cycle of development of such plants is called isomorphic diplohaplont (dictyota of the brown algae type, ulva of the green type).

B. In some species, there are few of them, only gametes are haploid, and the entire vegetative life of the species is carried out in the diploid phase. Such a life cycle is called diplont (fucus from the type of brown algae).

D. In the vast majority of plants, the haploid and diploid phases are developed unequally, one of them predominates, more often diploid, the second, haploid, is reduced. Since the diploid and haploid phases are morphologically unequal, the development cycle is called heteromorphic diplohaplontic.

Lower plants show a huge variety of forms of reproduction and development cycles. Most higher plants have a heteromorphic diplohaplon development cycle. In typical cases, a sporophyte (diplont) is a morphologically well-developed green autotrophic plant that attaches itself to the soil and exists independently. The gametophyte (haplont) often loses the ability to exist independently, develops on the sporophyte and feeds on it, that is, heterotrophically.

The alternation of generations is a biologically important phenomenon that contributes to the survival of a species in the struggle for existence. Consider reproduction and alternation of generations on specific examples.

Alternation of generations - a natural change in organisms of generations that differ in the way. Organisms of many species can reproduce both asexually and sexually. In this regard, they speak of asexual and sexual generations of this species. The alternation of these generations in plants and animals has many common features. The boundary separating the sexual and asexual generations in the development cycle is a process. At the same time, as a result of the fusion of haploid ( i.e., containing a single set), a diploid ( i.e., containing a double set) zygote appears, and the sexual generation passes into asexual.

Development cycle of bryophytes: 1 - gametophyte; 2 - sporophyte; 3 - sporangium; 4 - dispute; 5 - young gametophyte; 6 - antheridium; 7 - archegonium; 8 - egg; 9 - sperm.

Life cycle of a hydroid polyp: 1 - hydroid polyp; 2 - the formation of jellyfish with testes and ovaries by asexual - budding; 3 - eggs and sperm; 4 - zygote; 5 - development of a new colony of polyps.

The development cycle of angiosperms: 1 - male gametophyte; 2 - female gametophyte; 3 - egg; 4 - pollen grain; 5 - young sporophyte; 6 - endosperm; 7 - cotyledons; 8 - ; 9 - microspores; 10 - macrospores.

Change of nuclear phases in plants: 1 - brown alga dictyota (gametophyte and sporophyte are equally developed); 2 — cuckoo flax moss (gametophyte dominates); 4 - green algae spirogyra (only zygotes are diploid). GAM - , OPL - , ZIG - zygote, MEY -

A regular change in the life cycle of organisms of generations that differ in the method of reproduction. In this case, one or more asexual generations of organisms are replaced by a generation of sexually reproducing organisms.

It is characteristic of organisms that reproduce both sexually and asexually.

There are alternation of generations:

primary

secondary

Primary alternation of generations consists in the regular alternation of sexual and asexual generations

Occurs:

Protozoa

Algae

higher plants.

In plants sexual generation represented by the gametophyte asexual- sporophyte.

Fern life cycle

Gametophytes (growths) with juvenile sporophytes germinating on them

Generation alternation:

isomorphic - similarities in morphology and lifespan between sporophyte and gametophyte

heteromorphic - differences in these traits

Secondary alternation of generations

widely found in animals.

It is noted in the forms of heterogony and metagenesis.

heterogony consists in the primary alternation of the sexual process and parthenogenesis.

Parthenogenesis - a form of sexual (but same-sex reproduction) reproduction of organisms, in which female germ cells (eggs, eggs) develop without fertilization.

Parthenogenesis:

rudimentary or rudimentary (does not go beyond the initial stages of embryonic development)

complete natural parthenogenesis (ends with the development of sexually mature individuals). It occurs in all types of invertebrates and in all vertebrates except mammals (parthenogenetic embryos die on early stages embryogenesis)

Example: in trematodes sexual reproduction is regularly replaced by parthenogenesis. In a number of organisms, heterogony depends on the season (rotifers, daphnia and aphids reproduce in autumn by zygogenesis (by fertilization of eggs and the formation of zygotes), and in summer - parthenogenesis.

Metagenesis consists in the alternation of sexual reproduction and vegetative (asexual) reproduction.

For example, hydra usually reproduce by budding, but when the temperature drops, they form germ cells. In coelenterates, at some stages of development, there is a transition from sexual reproduction to vegetative. In some marine coelenterates, the polypoid generation regularly alternates with the medusa. The polypoid generation is characterized by reproduction by the so-called strobilation (transverse constrictions), for the medusoid generation - sexually (fertilization of eggs, the formation of larvae and the development of polyps).

Questions for self-control?

Name the main methods of reproduction

List the forms of the sexual process, explain what is their essence?

What are the features of the sexual process in unicellular and multicellular organisms?

What is alternation of generations?

In what groups of organisms does alternation of generations occur and what are the features?

GENERATION ALTERNATION GENERATION ALTERNATION

a regular change in the life cycle of organisms of generations (generations, bionts) that differ in the way of reproduction. Animals distinguish between primary and secondary Ch. p. Primary Ch. p., characteristic of many the simplest, they consider the change of sexual generation by a generation that reproduces by non-sex cells (agametes). So, in foraminifers, alternating generations are represented by sexual and asexual individuals - gamonts and agamonts. Reduction division (meiosis) occurs before the formation of agametes, so the sexual generation is haploid, as are gametes, while the zygote and agamons are diploid. In sunflowers, some flagellates, meiosis is associated with the formation of gametes, to-rye are unities, a haploid stage of the life cycle. The same relationship is characteristic of all multicellular animals. Secondary Ch. p. found in animals in two forms. The alternation of the normal sexual process with parthenogenesis called. heterogony, and the alternation of sexual reproduction with asexual - metagenesis. Heterogony is characteristic of trematodes, some roundworms and rotifers, a number of arthropods, etc. Metagenesis is characteristic of tunicates and coelenterates, in which the sexual generation is represented by single free-swimming jellyfish, and asexual by sessile polyps. In plants, a haploid generation is distinguished - sexual, or gametophyte, and diploid - asexual, or sporophyte. The reproductive organs that form gametes develop on the gametophyte, while it can be bisexual (sphagnum, isosporous ferns, club mosses) or dioecious (certain brown algae, heterosporous ferns, club mosses and all higher plants). Organs of asexual reproduction (sporangia, zoosporangia) develop on the sporophyte, forming haploid spores as a result of meiosis, which then germinate into new sexual generations. The gametophyte and sporophyte are the same morphologically and in terms of life span (isomorphic N. p.) or sharply different (heteromorphic N. p.). Higher plants are characterized only by heteromorphic N. n. In algae, both forms are found. With isomorphic generational change, each of them is represented by an independently living individual (certain green, brown and many red algae), so that in the life cycle there are two (with a bisexual gametophyte) or three (with a dioecious gametophyte) independent and identical plants. With heteromorphic generational change, both develop either independently of each other (kelp, isosporous ferns, club mosses, horsetails), or one of the generations, being deprived of independent development, exists at the expense of the other (mosses and all seed plants), but one of the generations always prevails - either the gametophyte or the sporophyte. In higher plants, only bryophytes belong to the gametophytic line of evolution (with a predominance of gametophyte development in the peak), in which sporophyte, called. sporogon, develops in the form of a box with spores on the greenest plant, which is a gametophyte. All other higher plants belong to the sporophyte line of evolution (with a predominance in the sporophyte development cycle). At the same time, the sporophyte is a leafy plant, sporangia develop on Krom, and the gametophyte (growth) is less developed, short-lived and represented by a bisexual thallus living independently (all equally spore ferns, club mosses, horsetails), or microscopic. formations that develop partially or completely on the sporophyte and due to it (heterosporous ferns and club mosses, gymnosperms, flowering). (see SPOROPHYT, GAMETOPHYT).

.(Source: Biological encyclopedic Dictionary." Ch. ed. M. S. Gilyarov; Editorial: A. A. Babaev, G. G. Vinberg, G. A. Zavarzin and others - 2nd ed., corrected. - M.: Sov. Encyclopedia, 1986.)

Change of generations in the life cycle of organisms. At the same time, generations (generations) differ in the ways of reproduction. In some protozoa (for example, in foraminifera), the generation that reproduces with the help of gametes is replaced by a generation that reproduces with non-sex cells. In tunicates and coelenterates, single free-swimming jellyfish represent the sexual generation, and polyps (sessile or colonial forms) represent the asexual generation.
In plants, the alternation of generations is expressed by a change in the development cycle of the haploid - sexual generation, or gametophyte, and diploid - asexual, or sporophyte. On the gametophyte, the reproductive organs develop, forming gametes; on the sporophyte - organs of asexual reproduction ( sporangia or zoosporangia), which as a result meiosis form haploid spores that give rise to a new sexual generation. At different plants either the sexual or asexual generation predominates in the development cycle. With the predominance of the sexual generation (in mosses), the sporophyte, or sporogon, develops on a green plant (gametophyte) in the form of a box with spores. With the predominance of the asexual generation (in ferns, club mosses, horsetails, gymnosperms), the sporophyte is represented by a green plant on which sporangia develop, and the gametophyte is poorly developed. outgrowth growing separately or developing on a sporophyte.

.(Source: "Biology. Modern Illustrated Encyclopedia." Editor-in-Chief A.P. Gorkin; M.: Rosmen, 2006.)

See what "ALTERNATION OF GENERATIONS" is in other dictionaries:

In plants, the alternation in the development cycle of two generations of sexual (gametophyte) and asexual (sporophyte). Invertebrates have a change in the life cycle of two or more generations of individuals that differ in form, function, lifestyle, and sometimes ... Big Encyclopedic Dictionary

alternation of generations- The natural change of different ways of reproduction of generations in the process of the life cycle; in animals, primary Ch.p. is distinguished, as well as heterogony and metagenesis; in many plants, Ch.p. represented by the formation of the gametophyte (sexual generation) and ... ... Technical Translator's Handbook

GENERATION ALTERNATION- English alternation of generation German Generationswechsel French alternance des générations see > ... Phytopathological dictionary-reference book

A regular change in organisms of generations that differ in the type of reproduction. Animals have primary and secondary Ch. p. The primary Ch. p., characteristic of many protozoa, is considered the change of sexual generation by generation, ... ... Great Soviet Encyclopedia

alternation of generations- ANIMAL EMBRYOLOGY different ways reproduction in the life cycle of animals. There are: 1) Alternation of generations, in which both generations are outwardly indistinguishable, but reproduce in different ... ... General Embryology: Terminological Dictionary

In plants, the alternation in the development cycle of two generations of sexual (gametophyte) and asexual (sporophyte). Invertebrates have a change in the life cycle of two or more generations of individuals that differ in form, function, lifestyle, and sometimes ... ... encyclopedic Dictionary

alternation of generations- kartų kaita statusas T sritis ekologija ir aplinkotyra apibrėžtis Augalų ir grybų haplofazės ir diplofazės kaita per gyvenimo ciklą. atitikmenys: engl. allelobiogenesis; allelogenesis; metagenesis vok. Allelogenesis, f; Metagenesis, f rus. change ... ...

alternation of generations- kartų kaita statusas T sritis ekologija ir aplinkotyra apibrėžtis Kai kurių bestuburių gyvūnų dauginimosi būdo kaita per jų gyvenimo ciklą – kaitaliojasi lytinė ir nelytinė kartos. atitikmenys: engl. allelobiogenesis; allelogenesis; metagenesis… … Ekologijos terminų aiskinamasis žodynas

Alteration of generation, digenesis, heterogenesis alternation of generations. Regular change of different methods of reproduction of generations in the course of the life cycle; in animals, primary Ch.p. is distinguished, as well as heterogony And… … Molecular biology and genetics. Dictionary.

alternation of generations- kartų kaita statusas T sritis augalininkystė apibrėžtis Raidos cikle dviejų kartų – haploidinės (gametofito) ir nelytinės diploidinės (sporofito) – pasikeitimas. atitikmenys: engl. alloiobiogenesis; heterogenesis; metagenesis rus. alternation ... ... Žemės ūkio augalų selekcijos ir sėklininkystės terminų žodynas

Plants have a biological phenomenon called alternation of generations. Alternation of generations describes the life cycle of a plant, how it changes between sexual and asexual phases (generations). The sexual phase of plants that produces, or is called the gametophyte generation. The asexual phase forms and is called the sporophyte generation. Each generation develops from the next, continuing the cyclical process. , including algae also exhibit this type of life cycle.

Reproduction of plants and animals

Plants and some animals are able to reproduce both and. In asexual reproduction, the offspring is an exact copy of the parent. different types asexual reproduction commonly found in both plants and animals include parthenogenesis (offspring develops from an unfertilized egg), budding (offspring develops through a bud on the parent's body), and fragmentation (offspring develops from a part or fragment of the parent). Sexual reproduction involves combining (cells containing only one set) to form (containing two sets of chromosomes).

In multicellular animals, the life cycle consists of one generation. A diploid organism produces haploid sex cells through. All other body cells are diploid and produced. A new diploid organism is created by the fusion of male and female germ cells during fertilization. In diploid organisms, there is no alternation of generations between haploid and diploid phases.

In vegetable multicellular organisms life cycles vary between diploid and haploid phases. In the diploid (sporophyte) phase, haploid spores are produced through meiosis. As haploid spores develop through mitosis, the multiplied cells form the haploid structure of gametophytes. The gametophyte is the haploid phase of the cycle. After maturation, the gametophyte produces male and female gametes (sex cells). When haploid gametes combine, they form a diploid zygote. The zygote develops through mitosis, forming a new sporophyte. Thus, unlike animals, plant organisms can alternate between diploid (sporophyte) and haploid (gametophyte) generations.

Vascular and non-vascular plants

Alternation of generations is observed in both vascular and non-vascular plants. Vascular plants contain a vascular tissue system that transports water and nutrients throughout the plant body. Non-vascular plants do not have such a system and need moist habitats to survive. These include mosses, anthocerotes and liver mosses. These plants look like green mats of vegetation with stems protruding from them. The primary phase of the life cycle of non-vascular plants is the generation of gametophytes. The gametophyte phase consists of green mossy vegetation, while the sporophyte phase consists of elongated stems with sporangia at the ends.

The primary phase of the life cycle of vascular plants is the generation of sporophytes. In vascular plants that do not produce seeds, such as ferns and horsetails, the sporophyte and gametophyte generations are independent. For example, in ferns, a branch with leaves is a mature diploid formation of sporophytes. The sporangia on the underside of the leaves produce haploid spores, which germinate to form haploid fern gametophytes (prothallium). These plants thrive in humid conditions, as water is essential for fertilization.

Vascular plants that produce seeds do not always depend on moist habitats to reproduce. The seeds protect the developing embryos. In both flowering and non-flowering plants (conifers), the generation of gametophytes is completely dependent on the dominant generations of sporophytes. IN flowering plants reproductive structure - flower. The flower produces both male microspores and female megaspores.

The microspores themselves are contained in pollen and are produced in the stamen of the plant, developing into male germ cells. Female megaspores are produced in plant pistils and develop into female gametes. During pollination, pollen is carried by wind, insects or other animals to the female part of the flower. Male and female gametes unite and develop into a seed, and the ovary forms a fruit. In conifers, pollen is produced in male cones, and in female cones after the embryo is formed.