List of Sub-Topics in Plant Ecology:

• Introduction
• Scope of Study
• Importance of Study
• Early Studies and Pioneers
• Milestones in the Development
• Applications and Future Development
• Conclusion
• Related Topics

Biology is a branch of science which studies living beings that all plants and animals including humans. It is a word derived from Greek words (Greek: bios = life; logos = study). No one can say when the study of biology exactly began but Greeks can be considered as the pioneer of an organized study of this branch of science. Botany is the scientific study of plants, including their structure, growth, reproduction, metabolism, evolution, ecology, and interactions with the environment. It is a branch of biology that encompasses a wide range of topics related to plant life, from the molecular and cellular levels to the ecosystem and global scales. In this article we shall discuss scope and importance of the study of botany.

Botany is the scientific discipline dedicated to the study of plants, including their structure, function, growth, reproduction, evolution, classification, and ecological relationships. It encompasses a wide range of subdisciplines, from plant anatomy and physiology to ecology, genetics, taxonomy, and biotechnology. Botanists study plants in diverse habitats, from microscopic algae to towering trees, and investigate their interactions with the environment and other organisms.

Scope of the Study of Botany:

The scope of study within botany, the scientific study of plants, is extensive and encompasses various subdisciplines. Here’s an overview of the scope of study within botany:

• Plant Anatomy and Morphology: Botanists study the internal structure and external morphology of plants, including tissues, organs, and reproductive structures. This involves microscopic examination, dissection, and comparative analysis to understand the diversity of plant forms and adaptations.
• Plant Physiology: Botanists investigate the physiological processes that occur in plants, including photosynthesis, respiration, water and nutrient uptake, hormone regulation, and responses to environmental stimuli. Understanding plant physiology is crucial for elucidating how plants grow, develop, and interact with their environment.
• Plant Taxonomy and Systematics: Botanists classify and categorize plants into hierarchical taxonomic groups based on shared characteristics and evolutionary relationships. This involves identifying, naming, and organizing plant species into a hierarchical classification system, which provides a framework for understanding plant diversity and evolution.
• Plant Ecology: Botanists study the interactions between plants and their environment, including the relationships between plants and other organisms, such as animals, fungi, and microbes. Plant ecologists investigate plant distribution patterns, community dynamics, ecosystem processes, and responses to environmental factors such as climate change, habitat loss, and pollution.
• Plant Genetics and Molecular Biology: Botanists study the genetic makeup and molecular mechanisms underlying plant traits, inheritance, and evolution. This includes genetic mapping, DNA sequencing, gene expression analysis, and genetic engineering techniques to manipulate plant traits for agricultural, medical, and environmental purposes.
• Plant Biotechnology and Bioprospecting: Botanists explore the potential applications of plants in biotechnology, medicine, and industry. This includes research on plant-derived pharmaceuticals, biofuels, biodegradable materials, and genetically modified crops with improved traits such as pest resistance, drought tolerance, and nutritional value.
• Plant Evolutionary Biology: Botanists investigate the evolutionary history and relationships among plants, including the origin and diversification of plant lineages over geological time scales. This involves comparative studies of plant fossils, phylogenetic analyses, and molecular dating methods to reconstruct the tree of life and understand patterns of plant evolution.
• Plant Pathology and Plant-Microbe Interactions: Botanists study plant diseases caused by pathogens such as fungi, bacteria, viruses, and nematodes. This includes identifying plant pathogens, understanding disease mechanisms, and developing strategies for disease management and crop protection. Botanists also investigate beneficial plant-microbe interactions, such as symbiotic relationships with mycorrhizal fungi and nitrogen-fixing bacteria.
• Ethnobotany and Traditional Plant Knowledge: Botanists document and study the traditional uses of plants by indigenous peoples and local communities for food, medicine, clothing, shelter, and cultural purposes. This interdisciplinary field integrates botany with anthropology, ecology, and conservation to promote the conservation of traditional plant knowledge and sustainable use of plant resources.
• Plant Conservation and Biodiversity: Botanists work to conserve and protect plant biodiversity through initiatives such as habitat conservation, ex situ conservation (e.g., botanical gardens, seed banks), restoration ecology, and species reintroduction programs. Botanists also assess the conservation status of plant species, identify threats to plant diversity, and develop conservation strategies to mitigate these threats.

Overall, the scope of study within botany is broad and interdisciplinary, encompassing various aspects of plant biology, ecology, evolution, and applications in fields such as agriculture, medicine, biotechnology, and conservation.

Importance of Study of Botany:

The study of botany, the scientific discipline dedicated to the study of plants, is of immense importance for several reasons:

• Understanding Plant Diversity: Botany provides insights into the incredible diversity of plant life on Earth, ranging from tiny algae to towering trees. By studying plant taxonomy, morphology, and genetics, botanists contribute to our understanding of plant evolution and classification, which is crucial for conservation efforts and sustainable management of plant resources.
• Food Security: Plants are the foundation of the food chain and provide the majority of our food supply. Botanical research plays a vital role in improving crop productivity, enhancing crop resilience to environmental stresses, developing disease-resistant varieties, and exploring new crops with nutritional value. This research is essential for ensuring global food security in the face of population growth and climate change.
• Medicinal and Pharmaceutical Discoveries: Many plant species produce bioactive compounds with medicinal properties, which have been used for centuries in traditional medicine practices. Botanical research contributes to the discovery, identification, and characterization of medicinal plants and their active compounds. This knowledge is instrumental in the development of new pharmaceuticals and treatments for various diseases and health conditions.
• Environmental Conservation and Restoration: Plants play crucial roles in maintaining ecosystem stability, regulating climate, filtering water, preventing soil erosion, and providing habitat for wildlife. Botanical research informs conservation efforts aimed at protecting plant biodiversity, restoring degraded habitats, and preserving endangered plant species and ecosystems. Understanding plant ecology and ecosystem dynamics is essential for addressing environmental challenges such as habitat loss, deforestation, and climate change.
• Climate Change Mitigation: Plants play a significant role in the global carbon cycle by sequestering carbon dioxide through photosynthesis and storing carbon in biomass and soils. Botanical research contributes to our understanding of how plants respond to changing environmental conditions, including increasing temperatures, altered precipitation patterns, and rising atmospheric carbon dioxide levels. This knowledge is essential for predicting the impacts of climate change on plant communities and ecosystems and developing strategies for climate change mitigation and adaptation.
• Biotechnology and Genetic Engineering: Botanical research provides the foundation for biotechnological advances in agriculture, medicine, and industry. Genetic engineering techniques allow scientists to manipulate plant genomes to improve crop traits, increase resistance to pests and diseases, enhance nutritional value, and develop plants with novel characteristics. Botanical research also contributes to the production of plant-based biofuels, biodegradable materials, and pharmaceuticals through biotechnological approaches.
• Educational and Recreational Value: Botanical gardens, arboreta, and natural reserves serve as living laboratories for botanical research, education, and public outreach. These institutions provide opportunities for students, scientists, and the general public to learn about plant biology, ecology, and conservation. Botanical gardens also contribute to the preservation of plant diversity, cultural heritage, and aesthetic appreciation of plants.

The study of botany is essential for advancing our understanding of plants and their importance to human health, food security, environmental conservation, and sustainable development. Botanical research contributes to addressing pressing global challenges and improving the quality of life for current and future generations.

Early Studies and Pioneers in Botany:

Botany has a rich history dating back thousands of years, with early studies conducted by pioneering scientists and philosophers from various cultures around the world. Here are some key figures and their contributions to the early development of botany:

• Theophrastus (c. 371 – c. 287 BC): Often referred to as the “Father of Botany,” Theophrastus was a Greek philosopher and student of Aristotle. His two major botanical works, “Enquiry into Plants” and “On the Causes of Plants,” are among the earliest surviving botanical texts. Theophrastus classified plants based on their growth habits and physiological characteristics and described hundreds of plant species, including their medicinal uses.
• Al-Jahiz (776–869 AD): An Arab scholar and naturalist, Al-Jahiz made significant contributions to botany and zoology. His work “Kitāb al-Hayawān” (Book of Animals) discussed plant morphology, classification, and adaptation to environmental conditions. Al-Jahiz also proposed early concepts of natural selection and evolutionary theory.
• Ibn al-Baitar (1188–1248 AD): An Andalusian botanist and pharmacist, Ibn al-Baitar authored “Kitāb al-Jāmiʿ li-Mufradāt al-Adwiya wa al-Aghdhiya” (Compendium on Simple Medicaments and Foods), a comprehensive botanical encyclopedia that described over 1,400 medicinal plants and their uses. Ibn al-Baitar’s work had a significant influence on later botanical studies in both the Islamic world and Europe.
• Leonhart Fuchs (1501–1566): A German physician and botanist, Fuchs published “De Historia Stirpium” (1542), one of the first modern botanical texts featuring accurate illustrations and descriptions of plants. His work contributed to the development of botanical illustration and the study of plant taxonomy.
• Carolus Clusius (1526–1609): A Flemish botanist known for his contributions to the study of plants, Clusius played a key role in introducing many new plant species to cultivation in Europe. He also made important contributions to the understanding of plant morphology and classification.

These early studies and pioneering figures laid the foundation for modern botany, shaping our understanding of plant diversity, morphology, physiology, and medicinal properties. Their contributions continue to inspire and inform botanical research today.

Milestones in the Development in Botany:

The development of botany, the scientific study of plants, has been marked by several key milestones that have shaped our understanding of plant biology, ecology, and applications. Here are some significant milestones in the field of botany:

• Systematization of Plant Classification by Linnaeus (18th century): Carl Linnaeus introduced the binomial nomenclature system, still used today, which provides a standardized way of naming and classifying plants based on their genus and species epithet. Linnaeus’s work laid the foundation for modern plant taxonomy and systematics.
• Introduction of Evolutionary Theory by Darwin (19th century): Charles Darwin’s theory of evolution by natural selection revolutionized the study of botany by providing a theoretical framework for understanding the origin and diversification of plant species. Darwin’s ideas reshaped botanical research and contributed to the emergence of plant evolutionary biology as a distinct field.
• Discovery of the Cell by Hooke and Leeuwenhoek (17th century): Robert Hooke’s observation of cork cells and Antonie van Leeuwenhoek’s discovery of microscopic organisms laid the groundwork for the study of plant anatomy and cell biology. Advances in microscopy allowed botanists to explore the cellular structure and organization of plants in greater detail.
• Development of Plant Physiology by Sachs (19th century): Julius von Sachs is often considered the founder of modern plant physiology. His experimental studies on plant nutrition, metabolism, growth, and development laid the foundation for understanding the physiological processes that occur in plants. Sachs’s work helped establish plant physiology as a distinct discipline within botany.
• Elucidation of Photosynthesis by Calvin and Benson (20th century): Melvin Calvin and Andrew Benson elucidated the biochemical pathway of photosynthesis, which is essential for the production of carbohydrates and oxygen by plants. Their research provided insights into the mechanisms of carbon fixation and energy conversion in photosynthetic organisms.
• Discovery of Plant Hormones (20th century): The discovery of plant hormones, such as auxins, gibberellins, cytokinins, and abscisic acid, revolutionized our understanding of plant growth and development. Hormones play critical roles in regulating various physiological processes in plants, including cell elongation, flowering, fruit ripening, and responses to environmental stimuli.
• Advances in Molecular Genetics and Genomics (late 20th century-present): The advent of molecular techniques, such as DNA sequencing, genetic engineering, and genome editing, has transformed botanical research. Genome sequencing projects have provided insights into the genetic makeup and evolutionary history of plants, while genetic engineering techniques have enabled the manipulation of plant genomes for agricultural, medical, and industrial purposes.
• Integration of Botany with Ecology and Conservation Biology (20th century-present): Botanical research increasingly emphasizes interdisciplinary approaches that integrate botany with ecology, conservation biology, and environmental science. This holistic approach allows scientists to address pressing environmental challenges such as habitat loss, climate change, and biodiversity conservation from a plant-centric perspective.
• Emergence of Plant Biotechnology and Bioprospecting (late 20th century-present): Advances in biotechnology have opened up new avenues for exploiting the potential of plants in agriculture, medicine, and industry. Plant biotechnology encompasses the use of genetic engineering, tissue culture, and other techniques to modify plants for improved traits, such as disease resistance, nutritional value, and biofuel production.
• Digital Revolution in Botanical Research (21st century): The digital revolution has transformed botanical research by providing access to vast amounts of data, computational tools, and online resources. Digital technologies, such as remote sensing, geographic information systems (GIS), and biodiversity databases, facilitate the study of plant distributions, ecology, and conservation on large spatial and temporal scales.

These milestones represent key developments in the field of botany, reflecting advances in theory, methodology, and interdisciplinary collaboration. Botanical research continues to evolve, driven by technological innovations, new discoveries, and the need to address pressing global challenges related to food security, environmental sustainability, and human health.

Applications and Future Development in Botany:

Botany, the scientific study of plants, has numerous applications and promising avenues for future development. Here are some key applications and potential directions for future research in botany:

• Agriculture and Crop Improvement: Botanical research contributes to the improvement of crop plants through breeding, genetic engineering, and biotechnology. Future developments may involve the development of crops with improved traits such as higher yields, enhanced nutritional value, resistance to pests and diseases, and tolerance to environmental stresses such as drought and salinity.
• Medicinal Plants and Drug Discovery: Many plant species produce bioactive compounds with medicinal properties, making them valuable resources for drug discovery and pharmaceutical development. Future research may focus on identifying novel medicinal plants, characterizing their bioactive compounds, and exploring their therapeutic potential for treating various diseases and health conditions.
• Climate Change Adaptation and Mitigation: Botanical research plays a crucial role in understanding how plants and ecosystems respond to climate change and in developing strategies for adaptation and mitigation. Future developments may involve studying the impacts of climate change on plant distributions, phenology, and ecosystem functioning, as well as developing climate-smart agricultural practices and carbon sequestration strategies using plants.
• Biodiversity Conservation and Restoration: Botanical research contributes to the conservation and restoration of plant biodiversity and ecosystems threatened by habitat loss, pollution, invasive species, and climate change. Future efforts may involve identifying and prioritizing conservation areas, restoring degraded habitats, reintroducing endangered plant species, and implementing strategies for ex situ conservation (e.g., botanical gardens, seed banks).
• Plant-based Biofuels and Renewable Resources: Botanical research explores the potential of plants as renewable resources for biofuel production, biodegradable materials, and other sustainable products. Future developments may involve the genetic engineering of plants for improved biomass production, enhanced conversion of biomass into biofuels, and the development of bio-based materials with reduced environmental impact.
• Urban Greening and Ecosystem Services: Botanical research contributes to the design and management of urban green spaces, parks, and gardens that provide multiple ecosystem services, such as air purification, climate regulation, storm water management, and biodiversity conservation. Future developments may involve using green infrastructure and nature-based solutions to enhance urban resilience, human well-being, and social equity.
• Ethnobotany and Traditional Knowledge: Botanical research collaborates with indigenous communities and local knowledge holders to document and preserve traditional uses of plants for food, medicine, culture, and spirituality. Future efforts may involve integrating traditional ecological knowledge with scientific research to promote sustainable resource management, community empowerment, and cultural revitalization.
• Digital Technologies and Data-driven Research: The integration of digital technologies, such as remote sensing, geographic information systems (GIS), and big data analytics, is transforming botanical research by providing tools for data collection, analysis, visualization, and dissemination. Future developments may involve harnessing the power of artificial intelligence, machine learning, and citizen science to address complex botanical challenges and opportunities on a global scale.

The applications and future development of botany are diverse and interdisciplinary, reflecting the importance of plants in addressing global challenges related to food security, health, climate change, biodiversity conservation, and sustainable development. Botanical research continues to evolve, driven by technological innovations, interdisciplinary collaborations, and the quest for solutions to pressing environmental and societal issues.

Conclusion:

Botany encompasses a broad scope of study that includes the scientific investigation of plants, their diversity, structure, function, ecology, and applications. The importance of botany is evident across various domains, from agriculture and medicine to environmental conservation and climate change mitigation. Botany covers a wide range of subdisciplines, including plant anatomy, morphology, physiology, taxonomy, ecology, genetics, biotechnology, and ethnobotany. Botanical research extends from the cellular and molecular levels to ecosystems and global scales, exploring plant diversity, evolution, adaptation, and interactions with the environment. Botanical research involves both observational and experimental approaches, combining fieldwork, laboratory experiments, and computational analyses. Botanists study plants in diverse habitats and ecosystems, from tropical rainforests to arctic tundra, and investigate plant responses to environmental factors, such as light, water, nutrients, temperature, and climate change.

Plants provide the majority of our food supply and contribute to global food security through crop improvement, plant breeding, and genetic engineering. Many medicinal drugs are derived from plant compounds, making botanical research essential for drug discovery and pharmaceutical development. Botanical research contributes to the conservation and restoration of plant biodiversity and ecosystems, addressing challenges such as habitat loss, pollution, and climate change. Plants play a crucial role in mitigating climate change by sequestering carbon dioxide through photosynthesis and providing ecosystem services such as carbon storage, soil stabilization, and habitat restoration. Botanical research supports sustainable development by providing renewable resources, biofuels, biodegradable materials, and nature-based solutions for addressing environmental and societal challenges.

In summary, botany is a diverse and interdisciplinary field with far-reaching implications for human health, food security, environmental conservation, and sustainable development. The study of botany is essential for understanding and preserving the vital role that plants play in supporting life on Earth and addressing pressing global challenges in the 21st century and beyond.

Related Topics:

What do we study in Botany?

• Plant Anatomy
• Plant Physiology
• Plant Morphology
• Plant Taxonomy and Systematics
• Plant Evolution and Genetics
• Plant Biotechnology
• Plant Pathology
• Applied Botany
• Ethnobotany

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In the previous article, we have studied the importance of biology. In this article, we shall study different branches of biology.

On the Basis of Kind of Organism:

Depending upon the kind of organism, the branches of biology are as follows:

• Botany: Botany is the scientific study of plants which include algae, fungi, lichens, mosses, ferns, conifers, and flowering plants.
• Zoology:  Zoology involves the study of animals including their classification, their history, their anatomy, and physiology,
• Microbiology: Microbiology is the study of all living organisms that are too small to be visible to the naked eye. This includes bacteria, archaea, viruses, fungi, prions, protozoa, and algae, collectively known as ‘microbes’.
• Human Biology: Human biology is the branch of biology that deals with human beings and human populations. It includes all the aspects of the human as an organism including genetics, ecology, anatomy and physiology, anthropology, and nutrition. Human biology is related to other fields of biology such as medicine, primate biology, and biological anthropology.

On the Basis of Group of Organisms:

Depending upon the group of organisms under the study, the branches of biology are as follows:

• Bacteriology: The science and study of bacteria and their relation to medicine and to other areas such as agriculture (e.g., farm animals) and the industry is called Bacteriology.
• Virology: Virology is the study of viruses and virus-like agents, including (but not limited to) their taxonomy, disease-producing properties, cultivation, and genetics. It is often considered a part of microbiology or pathology.
• Mycology: Mycology is the branch of biology that deals with the study of fungi. It includes the research of their genetic and biochemical properties and their use in medicine and food along with their hazards.
• Entomology: Entomology is a branch of zoology that studies insects and how they interact with their environment, other species and humans.
• Ichthyology: Ichthyology is the branch of zoology devoted to the study of fishes, which includes bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha).
• Herpetology: Herpetology is the branch of zoology concerned with the study of amphibians,  reptiles. Batrachology is a further subdiscipline of herpetology concerned with the study of amphibians only.
• Ornithology: Ornithology is the scientific field dedicated to the study of birds.

On the Basis of Approach to Study:

Depending upon the approach of the study, the branches of biology are as follows:

• Anatomy: It is the scientific study focusing on the physical structures and parts of organisms (plants and animals).
• Morphology: Morphology is a branch of biology dealing with the study of the form and structure (internal and external)  of organisms and their specific structural features
• Histology: Histology is the scientific study of the fine detail of biological cells and tissues using microscopes
• Cytology: The study of structure and function of plant and animal cells.
• Physiology: The branch of biology dealing with the functions and activities of living organisms and their parts, including all physical and chemical processes is called physiology.
• Embryology: Embryology is the study of the development of an embryo from the stage of ovum fertilization through to the fetal stage.
• Taxonomy or Systematics: The science of identifying, naming, grouping and classifying plants and animals is called taxonomy or systematics.
• Ecology: Ecology is the scientific study of the interactions between organisms and their environment.
• Biogeology: The study of the interaction between the Earth’s biosphere and the lithosphere.
• Biogeography: Biogeography is a study of the distribution of various species and ecosystems geographically and throughout geological time and space.
• Paleontology:  the study of fossils to determine the structure and evolution of extinct animals and plants and the age and conditions of deposition of the rock strata in which they are found is called Palaeontology.
• Evolution: evolution is the branch of biology which studies the change in the characteristics of a species over several generations and relies on the process of natural selection.
• Genetics: Genetics is a branch of biology that deals with heredity and variations.
• Parasitology: Parasites are those organisms that live on or inside other organisms called the host and draw nourishment from the host are called parasites. The study of parasites is called parasitology. It includes the study of three major groups of animals: parasitic protozoa, parasitic helminths (worms), and those arthropods that directly cause disease or act as vectors of various pathogens.
• Pathology: It is a branch of biology which studies diseases in plant and animals and their treatment.
• Immunology: The immune system protects us from infection through various lines of defense. Immunology is the study of the immune system.
• Eugenics: The study of or belief in the possibility of improving the qualities of the human species or a human population, especially by such means as discouraging reproduction by persons having genetic defects or presumed to have inheritable undesirable traits. Thus it is a science which aims to improve the human race through controlled heredity.
• Biochemistry: Biochemistry is the study of the processes behind all living organisms,

On the Basis of Agriculture and Allied Industries:

With respect to agriculture and allied industries, the branches of biology are as follows:

• Agriculture: It is a branch of biology which deals with raising crops and live stocks such as cows, buffaloes, etc.
• Veterinary Science:  The branch of medicine that deals with the causes, diagnosis, and treatment of diseases and injuries of animals, especially domestic animals.
• Marine Biology: Marine biology is the study of marine organisms, their behaviours, and their interactions with the environment.
• Horticulture: Horticulture is the science and art of producing, improving, marketing, and using fruits, vegetables, flowers, and ornamental plants.
• Animal Husbandry: It is the branch of agriculture concerned with animals that are raised for meat, fibre, milk, eggs, or other products. It includes day-to-day care, selective breeding and the raising of livestock like cows, buffaloes, etc.
• Sericulture: Sericulture, or silk farming, is the rearing of silkworms for the production of raw silk.
• Pisciculture: The breeding, rearing, and transplantation of fish by artificial means is called pisciculture.
• Tissue Culture: Tissue culture, a method of biological research in which fragments of tissue from an animal or plant are transferred to an artificial environment in which they can continue to survive and function.
• Molecular Biology: Molecular biology is a branch of science concerning biological activity at the molecular level. The field of molecular biology overlaps with biology and chemistry and in particular, genetics and biochemistry.
• Biotechnology: Biotechnology is the use of biological processes, organisms, or systems to manufacture products intended to improve the quality of human life.
• Cloning: Cloning is a process of asexual reproduction to create offspring that are genetically identical to the parent.
• Bioengineering: It is the branch of biology which with the help of engineering science help in making artificial limbs, joints and other parts of the body using engineering materials and techniques. It also includes the improvement of crops for disease resistance and yield.
• Biomedical Engineering: Biomedical engineering is the application of engineering principles to the fields of biology and health care. Biomedical engineers work with doctors, therapists and researchers to develop systems, equipment, and devices in order to solve clinical problems. The job includes the design, development, production, and maintenance of medical instruments.
• Nuclear biology: Nuclear biology or radiobiology is a branch of biology which studies the effect of radioactivity on living cell and also deals with the development and production of nuclear medicines for diagnosis and treatment of the diseases.
• Space Biology: The study of the survival of living things in a space is called space biology.
• Genomics: Genomics is a study of the genomes of organisms. Its main task is to determine the entire sequence of DNA or the composition of the atoms that make up the DNA and the chemical bonds between the DNA atoms.
• Bioinformatics: Bioinformatics is the application of information technology to the study of living things, usually at the molecular level. Bioinformatics involves the use of computers to collect, organize and use biological information to answer questions in fields like evolutionary biology.
• Biometrics: Biometrics is a technological and scientific authentication method based on biology and used in information assurance (IA). Biometric identification authenticates secure entry, data or access via human biological information such as DNA or fingerprints.
• Forensic science: The forensic sciences are used around the world to resolve civil disputes, to justly enforce criminal laws and government regulations, and to protect public health. The field of forensic science depends on other branches of science, including physics, chemistry, and biology, with its focus being on the recognition, identification, and evaluation of physical evidence. It has become an essential part of the judicial system to achieve information relevant to criminal and legal evidence.
• Genetic Engineering: Genetic engineering refers to the direct manipulation of DNA to alter an organism’s characteristics (phenotype) in a particular way.

On the Basis of Medical Sciences:

On basis of medical sciences, the branches of biology are as follows:

• Gynecology and Obstetrics: Gynaecology normally means treating women who aren’t pregnant, while obstetrics deals with pregnant women and their unborn children, but there is lots of crossover between the two.
• Orthopedics: It is a branch of medical science which is devoted to the diagnosis, treatment, prevention, and rehabilitation of injuries, disorders, and diseases of the body’s musculoskeletal system. This system includes bones, joints, ligaments, muscles, nerves, and tendons.
• Opthalmology: It is the branch of medicine that deals with the anatomy, physiology, and diseases of the eyeball and orbit.
• Dentistry: It is a branch of medicine that consists of the study, diagnosis, prevention, and treatment of diseases, disorders, and conditions of the oral cavity.
• Oncology: Oncology is the branch of medicine that researches, identifies and treats cancer.
• Cardiology: Cardiology is a branch of medicine that concerns diseases and disorders of the heart, which may range from congenital defects through to acquired heart diseases such as coronary artery disease and congestive heart failure.
• Urology: Urology is a surgical specialty that deals with the treatment of conditions involving the male and female urinary tract and the male reproductive organs.
• Nephrology: Nephrology is a branch of medical science that deals with diseases of the kidneys.
• Pediatrics: Pediatrics is the branch of medicine dealing with the health and medical care of infants, children, and adolescents from birth up to the age of 18.
• Dermatology: Dermatology is the branch of medicine dealing with diagnosing and treating skin diseases affecting the skin, hair, and nails.
• Physiotherapy: Physiotherapy is a branch of medicine which uses a treatment method that focuses on the science of movement and helps people to restore, maintain and maximize their physical strength, function, motion and overall well-being by addressing the underlying physical issues.

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The body of a typical flowering plant can be divided into the underground root system and aerial shoot system. The shoot system is heterogeneous.  The shoot system (stem) is an aerial and erect part of the plant body that grows upwards. It is usually above the soil and develops from the plumule of the embryo of a germinating seed. It consists of a stem, branches, leaves, flowers, fruits, and seeds. In this article, we shall very important of a plant, the leaf.

The leaf is lateral, generally flattened structure borne on the stem. A leaf may be defined as “A dorsoventrally compressed, lateral appendage of the stem, produced at the nodes and is specialized to perform photosynthesis. It develops at the node and bears a bud in its axil. The axillary bud later develops into a branch. Leaves originate from shoot apical meristems and are arranged in an acropetal (outward) order. They are the most important vegetative organs for photosynthesis.

Characteristics of Leaf:

• The leaf is a thin, expanded, green structure. The green colour is due to the presence of chlorophyll pigment.
• An auxiliary bud is present at the axil of each leaf.
• It is borne on the stem at the node, hence it is exogenous.
• It does not contain apical bud required for continuous growth hence it has limited growth.
• The lamina possesses prominent vascular strands called veins.
• Leaf bears abundant stomata for the exchange of gases.

The Structure of the Leaf:

A typical leaf consists of three main parts: leaf base, petiole, and lamina. The leaf is attached to the stem by the leaf base (hypo-podium) and may bear two lateral small leaf-like structures called stipules. The leaves with stipules are called stipulate leaves and the leaves without stipules are called ex-stipulate leaves. The main functions of stipules are to protect the bud and carry out photosynthesis. In monocotyledons, the leaf base expands into a sheath covering the stem partially or wholly. In some leguminous plants, the leaf base may become swollen, which is called the pulvinus. It protects the young axillary bud.

The petiole (mesopodium) is a cylindrical or sub-cylindrical smooth or grooved stalk of the leaf which lifts the lamina above the level of the stem.  Leaves that possess petiole are called petiolate leaves and those without petioles are called non-petiolate or sessile leaves. In papaya the petiole is hollow. The petiole help to hold the blade to light and also in conduction. Long thin flexible petioles allow leaf blades to flutter in wind, thereby cooling the leaf and bringing fresh air to the leaf surface.

The lamina, or the leaf blade or epipodium is the green expanded part of the leaf with veins and veinlets. There is, usually, a middle prominent vein, which is known as the midrib. Veins provide rigidity to the leaf blade and act as channels of transport for water, minerals and food materials. The shape, margin, apex, surface, and extent of incision of lamina varies in different leaves. The main functions of the lamina are photosynthesis and transpiration.

In dicots, the leaves are dorsiventral because its dorsal and ventral surfaces are structurally different. In monocots the dorsal and ventral surfaces of leaves are structurally identical, hence they are called isobilateral.

In some plants the shape and form of leaves are such that it is difficult to distinguish between the two surfaces, such leaves are called centric or cylindrical leaves. e.g. onion, garlic, etc.

Venation:

The arrangement of veins and the veinlets in the lamina of a leaf is termed as venation. Veins and veinlets are skeletal as well as conducting prominences visible on the surface of the lamina, especially the under surface in dorsiventral leaves.

Functions of Venation:

• Venation provides skeletal support to the lamina so that it can remain stretched for its optimum functioning,
• Veins and veinlets reduce the effect of wilting.
• They are important for the conduction of water and nutrients.

Types of Venation:

Reticulate Venation:

When the veinlets form a network, the venation is termed as reticulate. e.g. leaves of dicots,  Peepal (Ficus religiosa) (पीपल), Shoe-Flower (Hibiscus rosasinensis) (जास्वंदी), etc.(exceptions: Calophyllum, Corymbium, Eryngium).  It is further divided into two types.

Pinnate or Unicostate Reticulate Venation: 

The lamina has a single principal vein or midrib which extends from its base to apex. It gives rise to lateral veins along its entire length. Veins bear veinlets. The veinlets form reticulations. e.g. Mano, Peepal.

Palmate or Multicostate Reticulate Vena­tion: 

A number of prominent or principal veins arise from the tip of the petiole and reach either the apex or margins of the lamina. They give rise to lateral veins connected by reticulations of veinlets. It may be convergent (as in Ziziphus (बेर), Smilax) or divergent ( as in grapevine, lufia).

Parallel Venation:

When the veins run parallel to each other within a lamina, the venation is termed as parallel venation. There is a single principal vein or midrib that runs from base to the apex of the lamina. The lateral veins run parallel to one another without forming anastomoses e.g. leaves of monocots, maize, grass, banana (Musa paradisiaca), canna. etc. It is further divided into two types.

Pinnate or Unicostate parallel Venation: 

There is a single principal vein or midrib that runs from base to the apex of the lamina. The lateral veins run parallel to one another without forming anastomoses e.g. banana, canna

Palmate or Multiicostate convergent parallel Venation: 

Several parallel principal veins arise from the base of the lamina and converge towards the apex, e.g., Bamboo, Grass, etc.

Palmate or Multiicostate Divergent parallel Venation: 

Several parallel principal veins arise from the base of the lamina and proceed towards the margins, e.g., Fan Palm (Livistonia).

Furcate Venation:

The veins branch dichotomously. The finer branches do not form a reticulum. (e.g., ferm Adiantum, Circeaster)

Types of Leaves:

A leaf is said to be simple, when its lamina is entire or when incised, the incisions do not touch the midrib.

When the incisions of the lamina reach up to the midrib breaking it into a number of leaflets, the leaf is called a compound.

A bud is present in the axil of petiole in both simple and compound leaves, but not in the axil of leaflets of the compound leaf.

Types of Compound Leaves:

Pinnately Compound Leaves:

In a pinnately compound leaf, a number of leaflets are present on a common axis, the rachis, which represents the midrib of the leaf as in neem. They are further classified as

Unipinnate Compound Leaves: If the leaflets arise on primary rachis itself then it is known as unipinnate compound leaf. If the number of leaflets is odd it is known as imparipinnate compound leaf and if it is an even then it is known as a paripinnate compound leaf. Example: Azadirachta indica (Neem)

Bipinnately Compound Leaves: In this type, the primary rachis gets branched once and the leaflet arises on the secondary rachis. Example: Mimosa pudica (Touch me not)

Tripinnately Compound Leaves: In this type, the rachis gets branched twice and the leaflet arises on the tertiary rachis. Example: Moringa oleifera (drumstick)

Decompound Compound Leaves:

In this type, the rachis gets branched thrice or more than thrice and the leaflets arise on the ultimate branches. Example: Coriandrum sativum (coriander)

Palmately Compound Leaves:

In palmately compound leaves, the leaflets are attached at a common point, i.e., at the tip of the petiole, as in silk cotton.  On the basis of the number of leaflets they are further classified as

• Unifoliate Palmately Compound Leaves: With a single leaflet. Examples: Citrus limon (lemon), Citrus maxima (papanas).
• Bifoliate Palmately Compound Leaves: With two leaflets. Example: Bauhinia Yunnanensis (butterfly tree / kanher).
• Trifoliate Palmately Compound Leaves: With three leaflets. Example: Clover (Ran methi).
• Quadrifoliate Palmately Compound Leaves: With four leaflets. Example: Oxalis, MarsileaMultifoliate Palmately Compound Leaves: With more than four leaflets. Examples: Baobab, Umbrella plant.

Phyllotaxy:

Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. This is usually of three types alternate, opposite and whorled.

• In an alternate type of phyllotaxy, a single leaf arises at each node in an alternate manner, as in China rose, mustard and sunflower plants.
• In the opposite type, a pair of leaves arise at each node and lie opposite to each other as in Calotropis and guava plants.
• If more than two leaves arise at a node and form a whorl, it is called whorled, as in Alstonia.

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In this article, we shall study the modification in stem in some plants for performing the functions other than its primary function. Primary functions of the stem are

• To support and orient the leaves in a manner that they are exposed to maximum sunlight and for efficient gaseous exchange during photosynthesis and respiration.
• To conduct water and minerals from roots to leaves and manufactured food from leaves to different parts of the plant.
• To bear flowers and fruits

Some stems perform the function of storage of food, support, protection, and vegetative propagation. The secondary functions of the stem are

Underground Modification of Stem:

Since underground, they may seem like roots but they have characteristics of the stem, like the presence of nodes and internodes, scaly non-green leaves and buds. This modification serves two functions it acts as perennating structures by remaining leafless and dormant in winter but giving off aerial shoots under favourable conditions (next season) and Store food and become thick and fleshy.

Rhizome:

It is a prostrate, dorsoventrally thickened brownish stem, which grows horizontally under the surface of the soil. It shows distinct nodes and internodes. It shows distinct nodes and internodes. It bears scale leaves on nodes, It possesses terminal bud and axillary buds in the axil of each scale-leaf present at the node. Adventitious roots are present. e.g. Ginger (अद्रक), Turmeric (हलदी).

Stem Tuber:

Tubers are actually the swollen tips of ends of special underground branches swollen due to the storage of food as starch. The tubers show nodes and internodes. Nodes bear scale leaves with axillary buds, commonly called eyes. Under favourable conditions eyes sprout and produce aerial roots. Thus tubers help in vegetative propagation. They do not produce adventitious roots. e.g. Potato (आलू).

Bulb:

It is a condensed disc like an underground stem. The upper surface of the disc-like stem is conical and bears centrally placed apical bud and many concentrically arranged overlapping scale leaves. Scale leaves store food.  When the scale leaves surround the apical bud in the form of concentric rings, it is called a tunicated bulb. The lower surface of the stem produces adventitious roots. e.g. onion (प्याज).

When the scale leaves partially surround the apical bud by overlapping each other, it is called a scaly bulb. The lower surface of the stem produces adventitious roots. e.g. garlic (लहसुन).

Corm:

It is condensed disc-like underground, fleshy, spherical stem with flattened base, It grows vertically, bears many scale leaves, distinct nodes and internodes, buds and adventitious roots. e.g.  Saffron (केसर), yam (जिमीकंद), gladiolus.

Sub Aerial Modification Of Stem:

Stems are weak, therefore lie prostrate on the ground or may get partially buried in the upper layer of soil. The plants bearing such stems are called creepers. Their stems serve the function of vegetative propagation.

Runner:

The basal internodes of the bud elongate horizontally and trail along the soil carrying the bud to a distance from the mother plant where it gets fixed to the soil by means of adventitious roots and develops a new daughter plant. This branch carrying the bud is called a runner.  It grows in all the direction and a single plant soon covers a large area by its pro­geny. e.g. Grass, Oxalis, Centella asiatica, strawberry, etc.

Stolon:

When a weak lateral branch which grows upwards then arches down to meet the soil, strike roots and produce daughter plants. The difference between the runner and stolon is, runner grows horizontally, while stolen grow obliquely upward and then arches to the ground. e.g. Mint (‘Pudina’), Jasmine.

Offset:

Like runner but thicker and shorter, grow for a short distance then produce cluster (rosette) of leaves above and adventitious roots below; generally in aquatic plants. It is just like the runner, only it is shorter and thicker. e.g. water hyacinth (Eichhornia crassipes), pistia (Pistia stratiotes), water lettuce

Sucker:

An underground runner that grows horizontally for a distance under soil then emerges obliquely upwards, strikes roots and forms daughter plants. e.g. Chrysanthemum, Mentha arvensis, banana, pineapple etc.

Aerial Modification of Stem:

The whole stem or its part (axillary or terminal bud) gets modified to perform definite functions. It is a stem because they show characteristics like a) Arise in the axil of leaf b) Bear nodes and internodes c) may bear leaves, buds, flowers.

Stem Tendrils:

Stem or its branches get modified into green threadlike, spirally coiled leafless structures called tendrils which are meant for climbing. They twine around neighbouring objects and help weak plants to climb. These may be branched or unbranched. A scale leaf is always present at the point of branching of the tendril. e.g. Grapevine, cucumber, pumpkins, watermelon, etc.

Thorns:

These are straight, pointed, hard or woody structures sometimes they bear leaves, flowers or may be branched. Axillary buds of stems get modified into thorns (e.g. Citrus, Duranta, and Aegel). In Carrissa, terminal buds get modified into thorns. Thorns are used as organs of defence against grazing animals or climbing (e.g. Bougainvillea) and to check transpiration.

Phylloclade:

These are fleshy, green flattened or cylindrical branches of unlimited growth with nodes and internodes. The leaves are modified into spines or scales to check transpiration. This modification of stem is observed in plants growing in dry regions. The stem takes part in photosynthesis and stores water. e.g. Opuntia, Euphorbia, Casuarina, Cocoloba etc.

Cladode or Cladophylls:

It is a phylloclade with limited growth i.e. with only one or two internodes; help in photosynthesis. These are a green cylindrical or flattened leaf-like branches. In Asparagus, the cladodes are one internode long and in Ruscus, the cladodes are two internodes long. They help in photosynthesis.

Bulbil:

These are modified vegetative or floral buds with stored food and meant for vegetative propagation. In Dioscorea, bulbils are condensed axillary buds while in Agava and lily the floral buds develop into bulbil. They detach to develop into a new plant.

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The body of a typical flowering plant can be divided into the underground root system and aerial shoot system. The shoot system is heterogeneous. The shoot system (stem) is an aerial and erect part of the plant body that grows upwards. It is usually above the soil and develops from the plumule of the embryo of a germinating seed. It consists of stem, branches, leaves, flowers, fruits, and seeds.

The Stem:

The stem is negatively geotropic (moves above the soil), negatively hydrotropic (moves away from the water) and positively phototropic (moves towards the light). Branches arise from axillary buds present in the axil of leaves. Each axillary bud is a small, compact, underdeveloped shoot covered with a large number of overlapping leaf primordia. Internodes of this bud enlarge and develop into a branch. Therefore the development of branches is exogenous (exo = outside).

Characteristics of Stem:

• Stem arises as a prolongation of plumule (one end of an embryo).
• The shoot system is heterogeneous and consists of stem, branches, leaves, and flowers.
• The stem is negatively geotropic (moves above the soil), negatively hydrotropic (moves away from the water) and positively phototropic (moves towards the light). 
• The stem bears nodes and internodes. The regions of the stem where leaves are born are called nodes while internodes are the portions between two nodes.
• The stem bears vegetative buds which could be terminal (apical bud) for the plant to grow upwards or axillary (bud in the axil of the leaf) which give rise to lateral branches. The stem bears floral buds (terminal or axillary) that grow into flowers
• The young stem is green in colour and thus it is photosynthetic. The mature stem is generally green when young and later often become woody and dark brown.
• Lateral branches of the stem are exogenous in origin.

Functions of the Stem:

Primary functions of the stem are

• To support and orient the leaves in a manner that they are exposed to maximum sunlight and for efficient gaseous exchange during photosynthesis and respiration.
• To conduct water and minerals from roots to leaves and manufactured food from leaves to different parts of the plant.
• To bear flowers and fruits

Some stems perform the function of storage of food, support, protection and vegetative propagation. The secondary functions of the stem are

• Storage:  Some stems store food and water in some plants e.g. potato
• Perennation: The underground stems help tide over the unfavourable growing periods e.g. ginger, turmeric.
• Vegetative propagation: e.g. rose, and sugarcane the stem can be used for vegetative propagation.
• Photosynthesis: In xerophytes (desert plants) the leaves are reduced to thorn, the stem possessing chlorophyll takes up the function of photosynthesis. e.g.Opuntia
• Protection: In some plants, the axillary bud modifies into the thorn and protects the plants from grazing animals e.g. citrus, Duranta.
• Support, Climbing and Clinging: Tendrils or hooks are modified branches or buds. They coil around
  the support and help the plant to climb e.g. grapevine.

Types of Stem: 

The stem may be

• aerial (erect, rigid, strong and upright as in herbs, shrubs, and trees) or
• subaerial (weak, unable to stay upright and trail on the ground as creepers or climb up as climbers) or
• underground (buried in soil and produces aerial branches under favourable conditions only

Branching of Stem:

There are three main forms of branching.

• Excurrent:  the main trunk goes the entire height of the tree, with branches forming patterns; e.g. Evergreens, pinus.
• Decurrent: The main trunk continues up about halfway, then splits into more than one main branch; eg. fruit trees.
• Columnar or Coudex: The main trunk continues the full height of the tree, with the branches forming only at the top; eg. Palm trees, coconut tree.

Lateral Branching:

Branching is racemose or cymose according as the lateral buds are less vigorous or more vigorous than the apical bud.

Racemose Branching:

In racemose or monopodial branching the apical bud of the plant grows indefinitely giving rise to a straight stem axis or podium on which the lateral buds grow in acropetal succession, i.e. older branches are borne near the base and younger branches towards the apex.

This type of branching is the commonest among young Phanerogams. as the plant grows older, the apical bud often gets lost and some side branches become very strong so that the plant loses its monopodial character.

Instead of there being a single leaf at each node there be a whorl of leaves, the branches at each node will also be whorled. Then it is called whorled racemose.

Types of Buds:

Small lateral or terminal protuberance on the stem of a vascular plant that may develop into a flower, leaf, or shoot is called bud. Buds arise from meristem tissues. Flower buds are modified leaves. Buds are classified as follows:

Types of Buds on the Basis of Their Function:

Vegetative buds:

They contain embryonic leaves or shoots. They grow into new branches and shoots.

Floral buds:

They contain embryonic flowers. They grow into flowers. They are also referred as reproductive buds.

Mixed buds:

They contain both embryonic leaves and flowers. They may gro into vegetative parts like soot or leaf or into a flower part.

Tendrillar buds:

They grow into tendrils.

Types of Buds on the Basis of Its Position:

On the basis of the position of the buds, they are classified as terminal or apical buds and lateral buds.

Terminal or apical buds:

They develop at the apex of the main stem or branch. e,g, cabbage is a large apical bud

Lateral buds:

They develop into lateral branches or flowers. They are further classified as axillary buds, accessory buds, and sub-petiolar buds. Axillary buds are lateral buds that arise in the axil of the leaf, e.g. Sunflower, Citrus, Rose. Accessory buds are more than one bud that arises in the axil of a single leaf. e.g. Cucurbita, Luffa, Brinjal, Chilly, Bougainvillaea. Subpetiolar buds are axillary buds those are covered by a sheathing leaf base and appear to arise from the leaf base. As they remain dormant for a quite long time they are also referred as dormant buds. When they gro they are referred as sprouting buds. e.g. Dalbergia sissoo (Shisam) and Mulberry.

Bud Scales:

In some plants, buds are covered by overlapping scales, these scales are called bud scales. These bud scales are tough and may be modified leaves, leaf bases, petioles or stipules. e.g. Jackfruit, Ficus, and Magnolia.

Winter Buds:

In extremely cold regions plants bear specially protected buds called winter buds. During cold period leaves fall but the winter buds remain intact. During spring the bud opens with developing young leaves. e.g. Cauliflower, Cabbage.

Adventitious Buds:

They arise at a position other than their normal position. Epiphyllous or foliar buds arise on leaves. e.g. Begonia, Bryophyllum, etc. Cauline buds arise from the cut or pruned end of branches. e.g. Sweet potato, Coffee, Aegle, etc. Radical buds develop on the roots. e.g. Sweet potato, Dahlia, Dalbergia.

Turions Buds: 

A turion bud is a resistant plant bud that is found in certain aquatic plants and can allow the plant to survive winter in the vegetative state. e.g. Ultricularia, Potamogeton.

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In this article, we shall study the modification of roots for the purpose of food storage, respiration, support, etc. Roots in some plants change their shape and structure and become modified to perform functions other than absorption and conduction of water and minerals. They are modified for support, storage of food and respiration. We shall study the modification of roots for tap root system and adventitious system.

Modification of Tap Roots:

Modifications of Tap Root for Storage of Food:

Taproots of carrot, turnip and adventitious roots of sweet potato, get swollen and store food. The secondary roots remain thin. Hypocotyl, i.e. the embryonic region between cotyledons and radicle may also join the taproot in storing food. The stem is reduced and disc-shaped in the beginning and bears radical leaves.  Depending upon their shapes they are further classified into four types.

Modifications of Tap Root for Better Respiration:

The plants growing in saline, swamps, marshy places, and salt lakes are called halophytes. Such plants e.g.  Rhizophora growing in swampy areas (mangroves), many roots come out of the ground (negatively geotropic) and grow vertically upwards. Such roots, called pneumatophores. They help to get oxygen for respiration. The roots appear like conical spikes coming out of the water.  They occur in large numbers near the tree trunk. Exposed root tips possess Rhizophora minute pores (lenticels or pneumatothodes) through which roots respire. e.g. Rhizophora, Avicennia, Sonnerita, Heritiera (सुंद्री found in Sunderbans, Bengal).

Characteristics of Respiratory Roots:

• These are modified tap roots.
• These are non-green and non-photosynthetic
• They are found in marshy habitats like swamp and mangroves near seashores
• They grow vertically upward in response to gravity i.e. they are negatively geotropic.
• These roots are covered with cork and the gaseous exchange takes place through pores called lenticels

Nodulated Roots:

In legumes (pea family), the secondary roots of primary tap root bear small tubercles or swellings which are called root nodules. These nodules shelter nitrogen-fixing bacteria Rhizobium leguminosarum. They help in fixing atmospheric nitrogen into nitrates which can be absorbed by the roots.

Modifications of Adventitious Roots:

Modifications of Adventitious Root for Storage of Food:

Simple Tuberous Roots: 

These roots are creeping and become swollen and do not assume any shape. They are always borne singly. These roots arise from nodes of prostrate stem and enter in the soil. e.g. sweet potato (Ipomoea batatus) (शकरकंद).

Fasciculated Tuberous Roots: 

It is a cluster of adventitious roots for the storage of food. These roots have a definite shape. e.g. Dahlia, Asparagus (शतावरी)

Nodulose Roots:

Only apices of roots become swollen like single beads. e.g. mango, ginger, turmeric

Beaded or Moniliform Roots:

Roots alternately swollen and constricted which has beaded or moniliform appearance. e.g. Grasses, sedges, momordica.

Annulated Roots:

Looks like number of disc placed one above the other. e.g. Ipecac

Modifications of Adventitious Roots for Support:

Prop Roots:

The hanging structures that support a banyan tree are called prop roots. Roots develop from tree branches hang downwards and ultimately penetrate the ground, thus provide support to heavy branches. A banyan growing in Indian Botanical garden, Owrah (Kolkata) has nearly 1700 such prop roots and has a very large spread. The tree is about 200 years old. Another example is the mangrove plant Rhizophora.

Characteristics of Prop Roots:

• They arise from the branches of the stem.
• They hang down vertically and enter the soil.
• They are quite long.
• They behave like a pillar and give support to the plant.

Stilt Roots:

The stems of maize and sugarcane have supporting roots coming out of the lower nodes of the stem. These are called stilt roots. They are mainly found in monocots, shrubs and small trees. They grow obliquely downwards and penetrate the soil. Their primary function is to provide support to the plant. In plants like maize, bajra, sugarcane, jowar, they grow in whorls.  In screwpine(केवडा) or Pandanus (a tropical palm-like tree) these roots arise only from the lower surface of the obliquely growing stem to provide support. Another example is bamboo.

Characteristics of Stilt Roots:

• They develop from basal nodes of the stem.
• They grow obliquely from the stem.
• They are shorter in length
• They provide support to the plant as the ropes provide to the tent.

Climbing Roots:

Such plants produce roots from their nodes, by which they attach themselves to some support and climb over it. Weak climbers twine around and clasp the support with the help of climbing roots arising from their nodes. e.g. Money plant, black pepper (kali mirch), betel (pan). In Ivy, adhesive disc grows from climbing roots.

Clinging Roots: 

Special clinging roots arise, enter the crevices of support and fix the epiphyte. e.g. epiphytes orchids

Buttress Roots:

They are present at the basal part of the stem and spread in different directions in the soil. They are vertically elongated and horizontally compressed. They look like planks e.g. Ficus, Bombax, Terminalia.

Modifications of Adventitious Roots for Special Functions:

Epiphytic Roots:

Some plants like orchids grow on horizontal branches of big trees in the forest to get sunlight. They are autotrophic. These plants are called epiphytes. They develop special areal hanging roots called epiphytic roots. These roots are spongy. Due to the presence of velamen tissue are hygroscopic and have a porous wall. They absorb moisture from the atmosphere. e.g. vanda, dendrobium, etc. These roots are also called assimilatory roots due to their partial capacity of photosynthesis.

Sucking Roots or Haustoria or Parasitic Roots:

These are highly specialized and microscopic roots, developed by parasites to absorb nourishment from the host. In partial parasites penetrate only xylem element of the host and absorb water and minerals. E.g. Viscus album. In total parasites, they establish contact with both xylem and phloem of the host. Thus absorb water, minerals, and nutrients. e.g. Cuscuta, Orobanche, Viscum, Lorathus.

Floating Roots: 

Spongy, floating roots filled with air, arise from nodes of some aquatic plants, and help in floating and respiration. eg. Jussiaea

Photosynthetic or Assimilatory Roots: 

Roots which when exposed to sun develop chlorophyll, turn green and manufacture food. e.g. Tinospora (gilo) and orchids. In Tinospora, the roots arise as green hanging threads. Other examples are Taeniophyllum, Trapa ( Singhara), and Podostemon.

Characteristics of Assimilatory Roots:

• These are modified adventitious roots.
• These are green and photosynthetic
• They are found in diverse habitats like aquatic, terrestrial and epiphytes.
• They grow horizontally in response to gravity and hence referred as diageotropic similarly, they show branching pattern and hence they are also referred as plagiotropic.
• Gaseous exchange takes place through the general surface.

Mycorrhizal Roots: 

This is a symbiotic association between higher plants and fungus. In some plants, roots become associated with fungal hyphae. This association of a fungus with higher plants is called mycorrhiza. The fungus absorbs water and minerals from the soil, in turn, the plant provides organic food to the fungus. Example: Pinus, Monotropa

Reproductive Roots:

Adventitious roots of some plants develop buds that give rise to leafy shoots. These roots help propagation. Example: sweet potato

Contractile Roots:

These roots can be found on underground rhizome, bulb, tuber, corm, etc. of some plants. They maintain a proper level of the plant in the soil. Example: Cracus, Freesia, Canna.

Root Thorns:

In some plants, roots are modified by hard pointed thorn-like structures called root thorns. e.g. Pothos armatus and Acanthorrhiza.

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In this article, we shall study morphology of root, different regions of root, and different types of roots.

Morphology:

Morphology is a branch of biology dealing with the study of the form and structure of organisms and their specific structural features

Importance of Morphology:

• Knowledge of morphology is essential for the recognition or identification of organism.
• It is an important criterion for the classification of organisms.
• It gives information about the range of variations found in a species.
• Knowledge of morphology is required for studying various aspects of plant life like anatomy, physiology, genetics, ecology, etc.
• Deficiency and toxicity symptoms are morphological changes that occur in response to a shortage or excess of minerals.
• It forms the basis for breeding experiments.
• It helps in deciding methods of food processing and preservation.
• An ecological study of adaptation by the organism to the environment is studied using morphology.

Morphology of Flowering Plant:

The body of a typical flowering plant can be divided into the underground root system and aerial shoot system. The root system is homogeneous and consists of the main root and its lateral branches. The shoot system is heterogeneous and consists of stem, branches, leaves, and flowers. The parts of the plant body which are mainly concerned with important functions of nutrition and growth are called vegetative parts. e.g. root, stem, and leaves. The parts which perform the function of sexual reproduction are called floral or reproductive parts. e.g. flower.

The Root System:

The root system is the descending (growing downwards) portion of the plant axis. When a seed germinates, the radicle is the first organ to come out of it. It elongates to form the primary or the taproot. It gives off lateral branches (secondary and tertiary roots) and thus forms the root-system.

Characteristics of Roots:

• The root develops from the radicle of the embryo present in the seed.
• They are cylindrical generally non-green structures.
• They are homogeneous because they produce similar organs such as secondary and tertiary roots from the pericycle. i.e. they are endogenous.
• They are not differentiated into nodes and internodes.
• They do not produce dissimilar organs like leaves, buds.
• They are positively geotropic (moves towards the soil), positively hydrotropic (moves towards the water) and negatively phototropic (moves away from the light). 
• Generally, they are non-green and cannot synthesize food.
• The apex of the root is sub-terminal; because its tip is protected by a thimble-like structure called the root cap.
• It bears lateral rootlets which are always endogenous in origin.
• Root hairs are present near the tip of finer branches of root to increase the surface area of absorption of water and minerals.

Functions of Root:

• Its main functions are the absorption of water and minerals from the soil.
• It provides a proper anchorage to the plant parts.
• It transport absorbed water and minerals to the stem through the xylem.
• Storing reserve food material and synthesis of plant growth regulators are its other functions.
• By undergoing modifications in their structure, roots perform special physiological functions like food storage, assimilation, absorption of atmospheric moisture, sucking food from the host, better gaseous exchange and mechanical functions like floating (buoyancy), stronger anchorage and climbing.

Regions of the Root:

Root Cap Region:

The root is covered at the apex by a thimble-like structure called the root cap (Calyptra). It is produced by a meristematic zone. It protects the tender apex of the root as it makes its way through the soil. The cells of root cap secret mucilage which lubricates the passage of the root through soil. Mucilage also helps in the absorption of water and uptake of nutrient ions. Multiple root caps are present in pandanus (Screwpine). As the root grows further down in the soil, root cap wears out but it is constantly renewed. In aquatic plants like Pistia and water hyacinth (Eichornia)(जल कुंभी) root cap is like a loose thimble, called root pocket.

The Region of Meristematic Cells or Region of Cell Division:

Meristematic means rapid increasing or rapid growth. A few millimetres above the root cap is the region of meristematic activity. The cells of this region are very small, thin-walled and with a dense protoplasm and divide actively. In monocots, the root cap is formed by the independent group of cells known as Calyptrogen. The apical meristem consists of :

1. Dermatogen (outermost layer whose cells mature into epiblema and root cap);
2. Periblem (inner to dermatogen whose cells mature into cortex) and
3. Plerome (the central region whose cells mature into stele). 

The Region of Elongation:

The cells proximal to this region undergo rapid elongation and enlargement and are responsible for the growth of the root in length. This region is called the region of elongation.

The Region of Maturation:

The cells of the elongation zone gradually differentiate and mature. Hence, this zone, proximal to the region of elongation, is called the region of maturation. Matured cells differentiate into various tissues like root hairs and permanent region.

From this region some of the epidermal cells form very fine and delicate, thread-like structures called root hairs. This region is called the piliferous region. The root hairs are elongated, single-celled tubular structures that remain in contact with soil particles. The root hairs increase the surface area of absorption. Root hairs are short-lived and are replaced every 10 to 15 days. These root hairs absorb water and minerals from the soil.

The permanent region (zone of differentiated cells) lies behind the root hair zone and is without hairs. It produces lateral roots, anchors the plant in soil and conducts water and minerals upwards. The enlarged cells in this region undergo differentiation to form different types of primary root tissues like cortex, endodermis, xylem, phloem, etc.

Types of Root System:

Taproot System:

In a majority of the dicotyledonous plants, the direct elongation of the radicle leads to the formation of the primary root which grows in the soil. It gives off lateral branches (secondary and tertiary roots) and thus forms the taproot system. All lateral branches are produced in acropetal succession, i.e. the older and longer branches are near the base and younger and shorter ones are near the apex of the main root. The primary roots and its branches constitute the taproot system. Taproot system is the characteristics of most of the dicots. e.g. roots in the mustard (Brassica) (सरसों), sunflower (Helianthus) (सूरजमुखी) plant.

This system of roots provides a very strong anchorage as they are able to reach very deep into the soil. The deep feeder root system is also called the racemose taproot system. In some plants, the taproot remains short but the secondary roots grow horizontally to large extend along the surface of the soil and do not penetrate deep in the soil. such roots are called surface feeders.

Characteristics of Tap Root System:

• It develops from the radicle of the embryo.
• It is always underground.
• There is one main root with branches arising in an acropetal manner.
• The main or primary root persists throughout the life of the plant.
• These roots penetrate deep into the soil. Hence they act as a deep feeder.

Adventitious or Fibrous Root System:

In monocotyledonous plants, the primary root is short-lived and is replaced by a large number of roots. A cluster of slender, fibre-like roots arises from the base of the radicle and plumule which constitute the fibrous system of roots. e.g. roots in wheat (गेहूँ), maize (मक्का), sugarcane (गन्ना). In some plants, like grass (घास), Monstera (a tropical American vine having roots that hang like cords and cylindrical fruit with a pineapple and banana flavour) and the banyan (बरगद) tree, roots arise from parts of the plant other than the radicle and are called adventitious roots. Such roots can develop from the base of stem, nodes or from leaves. They do not branch profusely,  are shallow and spread horizontally, do not grow deep in the soil, hence cannot provide strong anchorage to the plant.

Characteristics of Adventitious Root System:

• It may arise from any part of the plant except radicle.
• It may be underground or aerial.
• Many roots arise in clusters of the same size.
• The primary root is short-lived and in plant’s life, it is replaced by adventitious roots.
• These do not penetrate deep in the soil.

Note:

Some aquatic plants like Utricularia, Wolfia, Ceratrophyllum, Myriophyllum, and Lemna do not have roots. Their submerged parts perform the functions of the root.

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