Biological Sciences
Plant Reproductive Cycle
The plant reproductive cycle involves the process of producing new plants through the formation of seeds. It typically includes pollination, fertilization, and seed dispersal. In flowering plants, the cycle begins with the production of flowers, followed by pollination and fertilization, leading to the development of seeds. This cycle ensures the continuation of plant species.
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10 Key excerpts on "Plant Reproductive Cycle"
- Shoichi Kawano(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
BIOLOGICAL APPROACHES AND Copyright © 1990 Academic Press Limited EVOLUTIONARY TRENDS IN PLANTS ISBN 0-12-402960-4 All rights of reproduction in any form reserved 274 K. M. Urbanska II. Reproduction in the Angiosperms - Different Ways and Means, the Same Effect Reproduction has a very special place amongst the basic functions of a live organ-ism: it secures the formation of the offspring. Reproductive behaviour of flowering plants is frequently characterized both by sexual and asexual processes, and influ-enced not only by genetic make-up but also phenotypic plasticity. All these differ-ences notwithstanding, a successful reproduction has but one outcome viz. the ap-pearance of active descendants contributing to the population turnover. The essential role of reproduction has been recognized in the numerous defini-tions which identify the reproductive process with the formation of new individu-als, but some authors still emphasize the production of propagules rather than the appearance of the new plants (Table 1). Last but not least, some scientists (e.g. Grime, 1979) renounce the term reproduction and propose to replace it by regeneration, whereas others (e.g. Harper, 1977) limit the reproduction to some specified conditions (Table 1). TABLE 1 Some definitions of reproduction Definition Authors) Ability of organism to produce new individuals of the same kind; this process is essential to preservation of species. Hartmann, 1959 Reproduction involves the formation of a new individual from a single cell; this is usually (though not always, e.g. apomicts) a zygote. In this process, a new individual is reproduced by the information that is coded in all that cell. Harper, 1977 Production of sexual or asexual propagule which starts a new developmental cycle and a new organism.
eBook - ePubEmbryology of Flowering Plants: Terminology and Concepts, Vol. 3
Reproductive Systems
- T B Batygina(Author)
- 2019(Publication Date)
- CRC Press(Publisher)
PART ONE–PLANT REPRODUCTION
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OVERVIEW
Reproductive Biology
Reproductive processes have exceptional significance not only in regular renewal of plant cover, but also in restoration of the foundation of our existence — the diverse world of plants, which has been disturbed in consequence of the continuous rise in anthropogenic pressures. Hence, repeated attempts to draw the attention of scientists to the problems of reproduction, and especially seed propagation, are well justified.Levina (1981) undertook one such attempt in her book Reproductive Biology of Seed Plants. Problem Review (Fig. 1 ). While highly appreciating this work and realizing its importance for the development of our knowledge on reproductive processes in plants and approaches to their investigation, we find that certain aspects of concepts that entered our scientific practice in the context of reproductive biology should now be critically evaluated. This needs to be done because the reproductive biology in Levina’s work is represented as a new synthetic approach to the study of reproductive cycles. The question that could and should be raised nowadays is whether the notion “reproductive biology” reflects a new scientific problem and consequently a new scientific approach, or whether it is only a more modern designation of a particular area of research in botany.According to Levina, plant reproductive biology developed gradually from the direction of plant reproduction and propagation studies, which was earlier referred to as “biology of propagation”. She emphasized that reproductive biology is first of all distinguished by a larger volume of investigations, connected with various levels of study of propagation processes. The biology of propagation has been studied just at the organism level and has taken into consideration hereditary morphophysiological peculiarities of an organism, whereas reproductive biology is studied at the species level and reflects the dependence of propagation on the ecological situation.
eBook - PDF- Rajesh Singh(Author)
- 2020(Publication Date)
- Delve Publishing(Publisher)
Similarly, the vegetative method has different sub -methods like cutting, budding, layering, separating, and grafting which are being used for producing the new plant which is similar to their parent plant. The sexual reproduction process takes place through pollination. Pollination is a process known as the sexual process which is used by the plants for reproduction. In this method, there is an involvement of male and female gametes that fuses together to form a new plant through an embryo. There are typically two types of pollination methods like self-pollination and cross-pollination which is being explained in detail. 2.1. INTRODUCTION Reproduction is a process that takes place in order to produce the new offspring in the plants. Therefore, the reproduction process is required for the generation of new individuals. Plants that are present on the land are considered to have asexual reproduction process, where the offspring are found to be genetically identical to their parents or sexual by creating a genetic variation. The life cycle of the plants basically involves two alternating generations: sporophytes that are making the spores and the gametophyte that is producing the make and the female gametes. During the evolution in the land plant, the life cycle has been altered from the gametophyte generation. It is observed that the structure that is making the gametes and spores, and the way through which the reproductive cells are being exchanged and dispersed. It also becomes altered, as the plants become to adapt the living in the drier environments. Flowers are representing the reproductive organ of the flowering plants and considered to be very important for the identification as it is typically providing the characters that are steadily being expressed within a taxon. Plant Reproduction 31 This is because the floral characteristics are basically under strong genetic control and it is not affected by the changes in the environments.
eBook - ePub- Charles Adams, Mike Early, Jane Brook, Katherine Bamford(Authors)
- 2015(Publication Date)
- Routledge(Publisher)
4CHAPTERLevel 3Plant reproduction
Figure 4.1 Bees and other pollinating insects are attracted to large, colourful fl owers. The Iris shown has blue fl owers, a colour attractive to bumble bees, and tepals which can support the bee’s weight with nectar guides directing the bees towards nectaries at their baseThis chapter includes the following topics:• Inflorescence types• Pollination syndromes• Cross- and self-pollination mechanisms• The relevance of cross-and self-pollination to horticulture• Fertilization• Seed structure – endospermic and non-endospermic seeds• Seed dormancy• Seed quality – testing and treatments• Seed provenance and conservation• Fruit development, structure and classification• Asexual reproduction and vegetative propagationPrinciples of Horticulture. 978-0-415-85909-7 © C.R. Adams, M.P. Early, J.E. Brook and K.M. Bamford. Published by Taylor & Francis. All rights reserved. Figure 4.2 Inflorescences which are designed to maximize pollen dispersal and capture: (a) in a Betula (birch) left, female catkins; right, male catkins; (b) in grassesReproduction is the process by which new individuals are formed and hence the species is perpetuated. In plants this can be asexual, by means of a range of vegetative structures or it can be sexual resulting in seeds. Sexual reproduction has two key advantages for the plant. It gives rise to variation in a plant's offspring, enabling it to withstand environmental pressures and it also provides the means by which plants can colonize new areas, through dispersal of seeds, often enclosed within a fruit. Although plants produced from seed are genetically variable and will not be uniform in their growth and other characteristics such as size, flower colour etc., this variation can be controlled by skilled plant breeders (see F1 hybrids p. 47
eBook - PDF- Cecie Starr, Christine Evers, Lisa Starr, , Cecie Starr, Cecie Starr, Christine Evers, Lisa Starr(Authors)
- 2020(Publication Date)
- Cengage Learning EMEA(Publisher)
Life Cycles of Flowering Plants 29.1 Plight of the Honeybee 611 29.2 Flower Structure and Function 612 29.3 Sexual Reproduction in the Flowering Plant 615 29.4 Seeds and Fruits 618 29.5 Early Development 620 29.6 Asexual Reproduction in Plants 622 29.7 Plant Hormones 623 29.8 Growth Responses 628 29 A shower of pollen from a heliconia flower sprays the face of a spiderhunter sipping nectar from it. Pollen that sticks to the bird’s feathers can be transferred to another flower—pollinating it—on a subsequent visit. CONCEPT CONNECTIONS You may want to review what you learned about meiosis in sexual reproduction (Section 9.5), and the life cycles of angiosperms (15.7). This chapter also revisits plant cell structure and function (3.6, 28.5), starch (2.7), receptor proteins (3.3), turgor pressure (4.5), pigments (5.3), clones (7.1), asexual reproduction (9.2), senescence (9.4), polyploidy (10.8), cell signaling (13.6), viruses (14.7), gametophytes and pollen (15.2), arthropods (16.5), animal hormone function (26.2), circadian rhythms (26.4), monocots and eudicots (28.2), stem structure (28.3), root structure (28.4), and plant growth (28.6). Evolutionary themes include adaptive traits (12.3), convergent evolution (12.6), factors that reduce genetic diversity (13.5), mechanical isolation (13.6), and coevolution (13.7). iStockphoto.com/momnoi Copyright 2021 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
eBook - PDF- Mary Ann Clark, Jung Choi, Matthew Douglas(Authors)
- 2018(Publication Date)
- Openstax(Publisher)
32 | PLANT REPRODUCTION Figure 32.1 Plants that reproduce sexually often achieve fertilization with the help of pollinators such as (a) bees, (b) birds, and (c) butterflies. (credit a: modification of work by John Severns; credit b: modification of work by Charles J. Sharp; credit c: modification of work by "Galawebdesign"/Flickr) Chapter Outline 32.1: Reproductive Development and Structure 32.2: Pollination and Fertilization 32.3: Asexual Reproduction Introduction Plants have evolved different reproductive strategies for the continuation of their species. Some plants reproduce sexually, and others asexually, in contrast to animal species, which rely almost exclusively on sexual reproduction. Plant sexual reproduction usually depends on pollinating agents, while asexual reproduction is independent of these agents. Flowers are often the showiest or most strongly scented part of plants. With their bright colors, fragrances, and interesting shapes and sizes, flowers attract insects, birds, and animals to serve their pollination needs. Other plants pollinate via wind or water; still others self-pollinate. 32.1 | Reproductive Development and Structure By the end of this section, you will be able to do the following: • Describe the two stages of a plant’s lifecycle • Compare and contrast male and female gametophytes and explain how they form in angiosperms • Describe the reproductive structures of a plant • Describe the components of a complete flower • Describe the development of microsporangium and megasporangium in gymnosperms Sexual reproduction takes place with slight variations in different groups of plants. Plants have two distinct stages in their lifecycle: the gametophyte stage and the sporophyte stage. The haploid gametophyte produces the male and female gametes by mitosis in distinct multicellular structures. Fusion of the male and females gametes forms the diploid zygote, which develops into the sporophyte.
eBook - PDFPlant Physiology 7A
A Treatise: Physiology of Development: Plants and Their Reproduction
- F.C. Steward(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
T h e complexity of the responses and their sensitive adjustment to 3. PHYSIOLOGY OF R E P R O D U C T I O N 235 environmental and other factors, which will be discussed below, is evidence of this. M a n y higher plants have evolved at least two distinct mechanisms of reproduction : vegetative and sexual (cf. Chapter 1 by W e t m o r e and Steeves). W h e n reproducing vegetatively, some part—usually multicellular—is separated from the parent body to give rise to an entire and independent new plant, although it has been questioned sometimes, according to context, whether the members of such a clone are to be regarded, strictly, as separate individuals. Genetically this new plant is, of course, identical with its parent, apart from occasional somatic mutations. T h e second—sexual—method of reproduction is of course the only possible mechanism in all higher animals and also the only natural one in numerous higher plants (e.g., in almost all gymnosperms). Here, the new organism arises from the fusion of the haploid gametes, and in general the new individual has a unique genetic constitution which differs from that of either parent. T h e production of gametes in higher plants involves the production of specialized reproductive organs in flowers. In general, therefore, the appearance of the floral organs is regarded as the onset of sexual reproduction in higher plants. Some authors include in a third category, distinct from vegetative reproduction, those cases in which a single somatic cell m a y give rise to the new plant (but without nuclear fusion), and this would com-prise such cases as parthenogenetic production of seeds and agamo-spermy. However, in the following pages all cases in which an organism arises as a seed from the normally sexual reproductive parts, will be included in the discussion of sexual reproduction ; all others will be classed as vegetative reproduction.
eBook - PDF- Emea, N(Authors)
- 2018(Publication Date)
- Agri Horti Press(Publisher)
This ebook is exclusively for this university only. Cannot be resold/distributed. Plant Reproduction 211 DIAGRAM OF A DICOT PLANT One of the simplest methods of reproduction is when one cell divides and becomes two equal halves that will grow large enough to split again. With plants and animals that reproduce this way, each generation is identical to the one before. CELL DIVIDING DIAGRAM WITH ONE PARENT CELL Plant reproduction may be sexual, in which two parents produce a genetically different individual; or asexual, involving the propagation of plants that are genetically identical to the parent. THE SEXUAL PLANT LIFE CYCLE Sexual reproduction is important in providing genetic variability. All plants that reproduce sexually must go through meiosis. Meiosis is a unique kind of cell division during which the paired sets of chromosomes present in sexually mature plants, called sporophytes, are halved. Because they have the two sets of chromosomes, one from the male parent and the other from the female, the cells of sporophytes are called diploid . During this process, pairs of homologous, or identical, chromosomes, one from each parent, line up together. Crossing-over, or the exchange of genetic material between these homologous chromosomes, may occur at this time. Crossing-over is critical for producing some of the genetic variability in resulting offspring. Meiosis typically produces four haploid cells, each with one set of chromosomes, from a single diploid cell. These haploid cells become gametes-eggs and sperm. Without meiosis, sexually reproducing organisms would not have a mechanism for reducing the total chromosome number by half so that genetic variability can be introduced via crossing-over. Meiosis is a critical step that must occur prior to the fusion of sperm and egg, which restores the diploid chromosome number. Alternating Generations Plants undergo a two-phase cycle of sexual reproduction This ebook is exclusively for this university only.
- Caula A. Beyl, Robert N. Trigiano, Caula A. Beyl, Robert N. Trigiano(Authors)
- 2016(Publication Date)
- CRC Press(Publisher)
65 5 Sexual Reproduction and Breeding Timothy A. Rinehart, Robert N. Trigiano, Phillip A. Wadl, and Haley S. Smith In this second edition of Plant Propagation Concepts and Laboratory Exercises , we have combined the first edition Chapters 36, “Sexual Reproduction in Angiosperms,” and 37, “Breeding Horticultural Plants,” into this single chapter, “Sexual Reproduction and Breeding.” These top-ics are so closely related that we believe that concepts are best presented as one unit. In addition to combining the aforementioned chapters, we have added some high-resolution microscopic photographs of mitotic events that are comparable to the line drawings depicting the vari-ous phases of mitosis. We have maintained some black-and-white figures for clarity of presentation. Lastly, we have included in this edition a simple laboratory exer-cise involving the observation and frequency of mitotic phases in the cells of onion as seen in longitudinal sec-tions of root tips on prepared slides. Many horticultural crops are produced exclusively by vegetative or asexual means. Asexual reproduction using grafting, rooted cuttings, and various other meth-ods ensures clonal fidelity of a cultivar. Phenotypic and genetic variation in these crops is undesirable, especially if the consumer is expecting to purchase a plant that they have seen growing somewhere else or pictured in a catalog. For example, all Cornus florida L. (flowering dogwood) ‘Cherokee Sunset’ plants have yellow variegated leaves and pink bracts subtending the floral disk, and are produced exclusively by a grafting technique (Chapter 25). There is little variation using this technique, and it produces Concept Box 5.1 • Most plants exhibit alternation of generations. In this case, the plant generations are the sporophytic or diploid (2n) phase that produces spores and the gametophytic or haploid (n) phase that produces gametes. • The four parts of flowers are sepals, petals, anthers, and pistils.
eBook - ePubScience Knowledge for Primary Teachers
Understanding the Science in the QCA Scheme
- Linda Gillard(Author)
- 2013(Publication Date)
- David Fulton Publishers(Publisher)
pollination. Landing on a stigma of another type of flower means that the pollen does not develop further, but if it lands on a ripe stigma of the right type of flower, then it starts to grow. A tube emerges and grows through the style down towards the ovary. To enable this growth, it digests the style tissue, which both makes room for the growth and provides the energy needed. Once in the ovary, it grows towards a weak spot on the surface of the ovule and the nuclei carried in the pollen tube pass into the ovule and fuse with the female nuclei, and this fusion is fertilisation. The ovule is now called the seed and the ovary is called the fruit. These structures continue to develop and eventually the seeds will be dispersed (with or without the fruit) and some will settle where they can successfully germinate and grow into a new plant.Pollination depends on pollen being transferred from a ripe anther to a ripe style. In order for the greatest variation in the next generation, it is better if the pollen from one individual plant is used to pollinate a different plant (cross pollination). However, it is possible that it will be transferred from one flower to another flower on the same plant or even be transferred within the same flower (self pollination). The advantage of sexual reproduction is that it produces variety and, because of the way the sex cells develop, even self pollination gives rise to a new mixing of the parent’s genetic material, and so even self pollination is beneficial.Plant life cyclesA life cycle is a way of showing the developmental stages during the life of an organism. In some organisms, the stages are very distinct and look very different. Two good examples are the frog and the insect.Figure 3.4 Life cyclesWithin this life cycle are the processes of pollination and fertilisation already discussed. Once the seed has developed and been dispersed, it can then germinate to produce the young plant. This seedling begins to feed by photosynthesis, which enables it to grow and mature and so eventually produce flowers and new seeds. The seed contains the embryo plant and dried food reserves provided by the parent plant to enable it to germinate, a sort of packed lunch to last until it can make its own food! The seeds of many plants in our climate are adapted to remain dormant over the winter. Germination
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