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Plant Anatomy by B P Pandey: A Modern and Updated Approach to Plant Morphology and Development


Outline of the article ----------------------- H1: Plant Anatomy by B P Pandey: A Comprehensive Guide for Botany Students H2: Introduction H3: What is plant anatomy? H3: Why is plant anatomy important? H3: What are the main topics covered in the book? H2: The Cell-Structure and its Components H3: Chemical nature of protoplasm H3: Physical nature of protoplasm H3: Properties of protoplasm H3: The cell wall H3: The cell division H2: The Tissue H3: Types of tissue H3: Functions of tissue H3: Apical meristems H2: The Tissue System H3: The epidermal tissue system H3: The ground tissue system H3: The vascular tissue system H2: Anatomy of the Leaf and the Petiole H3: Structure of the leaf H3: Modifications of the leaf H3: Structure of the petiole H2: Ecological Anatomy H3: Adaptations of plants to different environments H3: Examples of ecological anatomy H2: Anatomy of the Floral Parts H3: Structure of the flower H3: Development of the flower H3: Structure of the fruit and seed H2: Anatomy in Relation to Taxonomy and Phylogeny H3: How anatomy helps in classification of plants H3: How anatomy reveals evolutionary relationships of plants H2: Embryology of Angiosperms H3: Pollination and fertilization H3: Development of the embryo and endosperm H3: Polyembryony and apomixis H2: Tissue and Organ Culture H3: Principles and techniques of plant tissue culture H3: Applications and limitations of plant tissue culture H2: Conclusion --- # Plant Anatomy by B P Pandey: A Comprehensive Guide for Botany Students ## Introduction Plant anatomy is the study of the internal structure and organization of plants. It is also known as plant morphology or phytotomy. Plant anatomy helps us to understand how plants grow, develop, function, and adapt to different environments. It also helps us to identify and classify plants based on their structural features. Plant anatomy is an important branch of botany, which is the science of plants. Botany students need to learn plant anatomy to gain a deeper insight into the diversity and evolution of plants. Plant anatomy also has many applications in agriculture, horticulture, forestry, medicine, biotechnology, and conservation. One of the best books for learning plant anatomy is "Plant Anatomy" by B P Pandey. This book was first published in 2001 by S. Chand Publishing. It has 643 pages and covers all the major topics related to plant anatomy. It also includes embryology of angiosperms, morphogenesis of angiosperm, and diversity and morphology of flowering plants. The book is written in a simple and lucid language, with clear diagrams and illustrations. It is suitable for degree, honors, and post-graduate students of botany. It is also useful for teachers, researchers, and professionals who are interested in plant anatomy. In this article, we will give you a brief overview of the main topics covered in the book. We will also provide some examples and facts to make it more interesting and informative. ## The Cell-Structure and its Components The cell is the basic unit of life. All living organisms are made up of one or more cells. Plants are multicellular organisms, which means they have many cells that perform different functions. The cell consists of two main parts: - The protoplasm, which is the living part of the cell. It includes the nucleus and the cytoplasm. - The cell wall, which is the non-living part of the cell. It surrounds and protects the protoplasm. ### Chemical nature of protoplasm Protoplasm is composed of various organic and inorganic substances that are essential for life. The organic substances include: - Carbohydrates, which are the main source of energy for the cell. They are made up of carbon, hydrogen, and oxygen atoms. Examples of carbohydrates are glucose, starch, cellulose, etc. - Proteins, which are the building blocks of the cell. They are made up of amino acids, which are linked by peptide bonds. Examples of proteins are enzymes, hormones, antibodies, etc. - Lipids, which are fats and oils that store energy and form membranes. They are made up of glycerol and fatty acids. Examples of lipids are triglycerides, phospholipids, steroids, etc. - Nucleic acids, which are the genetic material of the cell. They store and transmit information for the synthesis of proteins. They are made up of nucleotides, which consist of a nitrogenous base, a pentose sugar, and a phosphate group. Examples of nucleic acids are DNA and RNA. The inorganic substances include: - Water, which is the most abundant and important substance in the cell. It makes up about 70-90% of the protoplasm. It acts as a solvent, a medium for chemical reactions, a transport agent, and a temperature regulator. - Minerals, which are elements or compounds that are needed for various metabolic processes. They include macroelements (such as carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, potassium, calcium, magnesium, etc.) and microelements (such as iron, copper, zinc, manganese, molybdenum, boron, chlorine, etc.). ### Physical nature of protoplasm Protoplasm is not a homogeneous substance. It has a complex structure and organization. It consists of various organelles and inclusions that perform specific functions. The organelles are specialized structures that have their own membranes and DNA. They include: - The nucleus, which is the control center of the cell. It contains the chromosomes, which carry the genetic information. It also contains the nucleolus, which produces ribosomes. - The mitochondria, which are the powerhouses of the cell. They produce energy by breaking down glucose in a process called cellular respiration. - The chloroplasts, which are found only in plant cells. They contain chlorophyll, which is a green pigment that captures light energy for photosynthesis. - The endoplasmic reticulum (ER), which is a network of membranes that transports materials within the cell. It can be smooth (SER) or rough (RER). The RER has ribosomes attached to it, which synthesize proteins. - The Golgi apparatus, which is a stack of flattened sacs that modifies and packages proteins for secretion or storage. - The lysosomes, which are vesicles that contain digestive enzymes that break down waste materials and foreign substances. - The vacuoles, which are large sacs that store water, salts, sugars, pigments, and other substances. - The cytoskeleton, which is a network of protein filaments that provide shape and support to the cell. It also helps in cell movement and division. The inclusions are non-living substances that are stored or accumulated in the cell. They include: - Starch grains, which are insoluble carbohydrates that store energy. - Oil droplets or globules, which are lipids that store energy and act as buoyancy agents. - The primary wall, which is formed first during cell division. It is thin and flexible and allows cell growth and expansion. It is composed mainly of cellulose microfibrils embedded in a matrix of hemicellulose and pectin. - The secondary wall, which is formed later after cell growth has stopped. It is thick and rigid and provides strength and support to the cell. It is composed mainly of cellulose microfibrils arranged in layers with different orientations. It also contains lignin, which is a phenolic compound that imparts hardness and resistance to the wall. - The middle lamella, which is the outermost layer that cements adjacent cells together. It is composed mainly of pectin and calcium salts. It also contains some proteins and polysaccharides. ### The cell division The cell division is the process by which a cell divides into two or more daughter cells. It is essential for growth, development, reproduction, and repair of the organism. There are two types of cell division: - Mitosis, which is the division of the nucleus into two identical nuclei. It is followed by cytokinesis, which is the division of the cytoplasm into two equal parts. Mitosis results in two daughter cells that are genetically identical to the parent cell. Mitosis occurs in somatic cells (body cells) and produces diploid cells (cells with two sets of chromosomes). - Meiosis, which is the reduction division of the nucleus into four haploid nuclei. It is followed by cytokinesis, which is the division of the cytoplasm into four unequal parts. Meiosis results in four daughter cells that are genetically different from the parent cell. Meiosis occurs in gametes (sex cells) and produces haploid cells (cells with one set of chromosomes). Mitosis and meiosis have different phases: - Mitosis has four phases: prophase, metaphase, anaphase, and telophase. - Prophase: The chromosomes condense and become visible. The nuclear envelope breaks down. The spindle fibers form from the centrioles and attach to the centromeres of the chromosomes. - Metaphase: The chromosomes align at the equator of the cell. The spindle fibers pull them towards the opposite poles. - Anaphase: The sister chromatids separate and move to the opposite poles. The cell elongates as the spindle fibers contract. - Telophase: The chromosomes decondense and become invisible. The nuclear envelope reforms around them. The spindle fibers disappear. The cell divides into two daughter cells by cytokinesis. - Meiosis has two stages: meiosis I and meiosis II. Each stage has four phases: prophase I, metaphase I, anaphase I, telophase I, prophase II, metaphase II, anaphase II, and telophase II. - Meiosis I: The homologous chromosomes pair up and exchange segments in a process called crossing over. This creates genetic variation among the daughter cells. Then, the homologous chromosomes separate and move to the opposite poles. The cell divides into two haploid daughter cells by cytokinesis. - Meiosis II: The sister chromatids separate and move to the opposite poles. The cell divides into four haploid daughter cells by cytokinesis. ## The Tissue The tissue is a group of similar cells that perform a common function. There are three types of tissue in plants: - Meristematic tissue, which is composed of undifferentiated cells that divide rapidly and continuously. It is responsible for growth and development of the plant. It is found in regions such as root tips, shoot tips, cambium, etc. - Permanent tissue, which is composed of differentiated cells that have lost their ability to divide. It performs various functions such as support, transport, storage, photosynthesis, etc. It can be simple or complex. - Simple tissue, which is composed of one type of cell. It can be parenchyma (thin-walled living cells that fill spaces and store food), collenchyma (thick-walled living cells that provide flexibility and support), or sclerenchyma (thick-walled dead cells that provide rigidity and strength). - Complex tissue, which is composed of more than one type of cell. It can be xylem (conducts water and minerals from roots to shoots) or phloem (conducts food from leaves to other parts). - Secretory tissue, which is composed of specialized cells that secrete substances such as nectar, resin, latex, etc. It is found in various organs such as flowers, stems, leaves, etc. ## The Tissue System The tissue system is a group of tissues that work together to perform a specific function. There are three tissue systems in plants: - The epidermal tissue system, which covers and protects the external surfaces of the plant. It consists of epidermis (a single layer of cells that forms the outermost layer), cuticle (a waxy layer that prevents water loss), stomata (pores that allow gas exchange), trichomes (hairs that provide insulation or defense), and glands (structures that secrete substances). - The ground tissue system, which fills the spaces between the epidermal and vascular tissue systems. It consists of parenchyma, collenchyma, and sclerenchyma. It performs various functions such as storage, photosynthesis, support, etc. - The vascular tissue system, which transports materials throughout the plant. It consists of xylem and phloem. It also provides mechanical support to the plant. ## Anatomy of the Leaf and the Petiole The leaf is a flattened and green organ that is attached to the stem by a stalk called the petiole. The leaf is the main site of photosynthesis in plants. It also helps in transpiration, respiration, and gas exchange. The leaf has a complex structure and organization. It consists of three parts: - The leaf blade or lamina, which is the broad and flat part of the leaf. It has a dorsal (upper) and a ventral (lower) surface. It also has a margin (edge), an apex (tip), and a base (where it joins the petiole). - The leaf venation or venation pattern, which is the arrangement of veins in the leaf blade. The veins are extensions of the vascular tissue system that provide support and transport to the leaf. There are two types of leaf venation: parallel (veins run parallel to each other) or reticulate (veins form a network). - The leaf anatomy or internal structure, which is the organization of tissues in the leaf blade. The leaf anatomy can be studied by making a cross section or a longitudinal section of the leaf blade. The cross section of a typical dicotyledonous leaf shows three layers: - The upper epidermis, which is a single layer of cells that covers and protects the upper surface of the leaf. It has a thick cuticle and no stomata. - The mesophyll, which is the middle layer of cells that performs photosynthesis. It has two types of cells: palisade parenchyma (elongated cells that are arranged vertically and contain many chloroplasts) and spongy parenchyma (irregular cells that are arranged loosely and have air spaces between them). The mesophyll also contains vascular bundles (xylem and phloem) that run along the veins. - The lower epidermis, which is a single layer of cells that covers and protects the lower surface of the leaf. It has a thin cuticle and many stomata. The longitudinal section of a typical monocotyledonous leaf shows two layers: - The epidermis, which is a single layer of cells that covers both surfaces of the leaf. It has a thin cuticle and many stomata on both sides. - The mesophyll, which is a single layer of cells that performs photosynthesis. It has no differentiation into palisade and spongy parenchyma. It also contains vascular bundles that run parallel to each other. The petiole is a short and slender stalk that connects the leaf blade to the stem. It helps in supporting and orienting the leaf blade for maximum exposure to light. It also helps in transporting materials between the leaf and the stem. The petiole has a simple structure and organization. It consists of three parts: - The epidermis, which is a single layer of cells that covers and protects the surface of the petiole. It may have trichomes or glands. - The cortex, which is a layer of parenchyma cells that fills the space between the epidermis and the vascular tissue. It may store food or water. - The vascular tissue, which is a ring of vascular bundles that transport materials between the leaf and the stem. It may have collenchyma or sclerenchyma cells for support. ## Ecological Anatomy Ecological anatomy is the study of the structural adaptations of plants to different environmental conditions. Plants have to cope with various factors such as light, temperature, water, soil, wind, fire, etc. These factors affect the growth, development, and survival of plants. Plants show various anatomical modifications to adapt to different environments. Some examples of ecological anatomy are: - Xerophytes are plants that live in dry habitats. They have adaptations such as thick cuticle, sunken stomata, reduced leaf area, succulent tissues, etc. to reduce water loss and store water. Examples are cactus, euphorbia, etc. - Hydrophytes are plants that live in aquatic habitats. They have adaptations such as thin cuticle, abundant stomata, large air spaces, reduced vascular tissue, etc. to facilitate gas exchange and buoyancy. Examples are water lily, lotus, etc. - Halophytes are plants that live in saline habitats. They have adaptations such as salt glands, salt bladders, succulent tissues, etc. to excrete or store excess salts. Examples are mangrove, salicornia, etc. - Epiphytes are plants that grow on other plants. They have adaptations such as aerial roots, modified leaves, water-absorbing hairs, etc. to obtain water and nutrients from the air or rain. Examples are orchids, bromeliads, etc. - Parasites are plants that obtain nutrients from other plants. They have adaptations such as haustoria (specialized roots that penetrate the host tissues), reduced leaves and roots, modified flowers, etc. to exploit their hosts. Examples are mistletoe, dodder, etc. ## Anatomy of the Floral Parts The flower is a modified shoot that bears the reproductive organs of angiosperms (flowering plants). It is also the site of pollination and fertilization. The flower has a complex structure and organization. It consists of four whorls: - The calyx, which is the outermost whorl of the flower. It consists of sepals, which are usually green and leaf-like. They protect the flower bud and support the petals. The calyx may be free (sepals are separate) or fused (sepals are united). - The corolla, which is the second whorl of the flower. It consists of petals, which are usually colorful and showy. They attract pollinators and provide landing platforms for them. The corolla may be free (petals are separate) or fused (petals are united). - The androecium, which is the third whorl of the flower. It consists of stamens, which are the male reproductive organs. Each stamen has a filament (a stalk that supports the anther) and an anther (a sac that produces pollen grains). The androecium may be free (stamens are separate) or fused (stamens are united). - The gynoecium, which is the innermost whorl of the flower. It consists of carpels, which are the female reproductive organs. Each carpel has an ovary (a chamber that contains ovules), a style (a tube that connects the ovary to the stigma), and a stigma (a sticky surface that receives pollen grains). The gynoecium may be free (carpels are separate) or fused (carpels are united). The flower may have different types of symmetry: - Actinomorphic or radial symmetry, which means the flower can be divided into equal halves by any plane passing through the center. Examples are buttercup, rose, etc. - Zygomorphic or bilateral symmetry, which means the flower can be divided into equal halves by only one plane passing through the center. Examples are pea, orchid, etc. - Asymmetric or irregular symmetry, which means the flower cannot be divided into equal halves by any plane passing through the center. Examples are canna, fuchsia, etc. The flower may also have different types of attachment: - Hypogynous or superior ovary, which means the ovary is above the level of attachment of other floral parts. The flower is said to have a free hypanthium (a cup-like structure formed by the fusion of sepals, petals, and stamens). Examples are lily, tulip, etc. - Perigynous or half-inferior ovary, which means the ovary is at the same level of attachment of other floral parts. The flower is said to have an adherent hypanthium. Examples are cherry, apple, etc. - Epigynous or inferior ovary, which means the ovary is below the level of attachment of other floral parts. The flower is said to have an inferior hypanthium. Examples are banana, cucumber, etc. ## Anatomy of the Embryo and Young Seedling The embryo is a young plant that develops from a fertilized egg or zygote. It is enclosed within a seed coat and contains a food reserve called endosperm. The embryo has a simple structure and organization. It consists of three parts: - The radicle, which is the embryonic root. It grows downwards and anchors the plant in the soil. It also absorbs water


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