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Description of flowering plants in botanical terms in relation to taxonomyNew Microsoft PowerPoint Presentation.pptx

The document describes key aspects of plant taxonomy and classification systems. It discusses: 1) The main parts of a flower - calyx, corolla, androecium, gynoecium - and their characteristics. 2) Taxonomy systems including artificial, natural, and phylogenetic and how they classify plants. 3) Modern trends in plant taxonomy including morphological, anatomical, palynological, chemotaxonomic, and numerical approaches.

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COLLEGE OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY ANDUAT, AYODHYA SUBJECT-BasicConceptsin LaboratoryTechniques(PGS603) ASSIGNMENT TOPIC : Description of flowering plants in botanical terms in relation to taxonomy Suggested by – Dr. Chandra Shekhar (Professor) Dept. of Public Health & Epidemiology Presented by SHARDENDU NARAYAN GIRI Id. No. :V-10600/18/23 , Phd, 1st Year, 1st Semester DEPARTMENT OF LIVESTOCK PRODUCTION MANAGEMENT
The Description of Flowers
 The flower is the reproductive unit in the angiosperms.  A typical flower has four different kinds of whorls  Calyx  Corolla  Androecium  Gynoecium  When a flower has both androecium and gynoecium, it is bisexual.  A flower having either only stamens or only carpels is unisexual.
Calyx  The calyx is the outermost whorl of the flower and the members are called sepals.  Generally, sepals are green, leaf like and protect the flower in the bud stage.  The calyx may be gamosepalous (sepals united) or polysepalous (sepals free).
Corolla  Corolla is Composed of petals.  Petals are usually brightly colored to attract insects for pollination.  Like calyx, corolla may also be gamopetalous (petals united) or polypetalous (petals free).  The shape and colour of corolla vary greatly in plants.  Corolla may be tubular, bell-shaped, funnel-shaped or wheel-shaped
Androecium  Androecium is composed of stamens.  Each stamen which represents the male reproductive organ consists of a stalk or a filament and an anther.  Each anther is usually bilobed and each lobe has two chambers, the pollen-sacs.  The pollen grains are produced in pollen-sacs.
 Stamens of flower may be united with other members such as petals or among themselves.  When stamens are attached to the petals, they are epipetalous or epiphyllous.  The stamens in a flower may either remain free (polyandrous) or may be united in varying degrees.  The stamens may be united into one bunch or one bundle (monoadelphous) or two bundles (diadelphous) or into more than two bundles (polyadelphous).  There may be a variation in the length of filaments within a flower.
Gynoecium  Gynoecium is the female reproductive part of the flower and is made up of one or more carpels.  A carpel consists of three parts namely stigma, style and ovary.  Ovary is the enlarged basal part, on which lies the elongated tube, the style.  The style connects the ovary to the stigma.  The stigma is usually at the tip of the style and is the receptive surface for pollen grains.  Each ovary bears one or more ovules attached to a flattened, cushion-like placenta.
 When more than one carpel is present, they may be free (as in lotus and rose) and are called apocarpous.  They are termed syncarpous when carpels are fused, as in mustard and tomato.  After fertilisation, the ovules develop into seeds and the ovary matures into a fruit.
Taxonomy
What is Plant Taxonomy?  The term “taxonomy” originates from two words, “taxis” meaning arrangement and “nomos” meaning laws.  The term taxonomy was coined by the Swiss botanist A. P. de Candolle in his book “Théorie élémentaire de la botanique”.  Plant taxonomy can be defined as the branch of botany which deals with characterization, identification, classification and nomenclature of plants based on their similarities and differences.  Characterization: To describe all the characteristics of the newly identified species  Identification: Identify the unknown species based on its characteristics and by comparing with already existing species  Classification: Placing and arranging the known species into different groups or taxa according to similarities and dissimilarities  Nomenclature: Giving the scientific name according to the convention.
 Organisms are categorized into different taxonomic categories according to the similarities and specific features.  The different taxonomic categories in their hierarchical order are: Kingdom Phylum Class Order Family Genus Species  The number of common characteristics decreases as we move from species to the kingdom, where species having fundamental similarities and organisms in the same kingdom having least common features.
Systems of Plant Taxonomy  There are three main types of systems for plant classification. 1.Artificial systems 2.Natural systems 3.Phylogenetic systems
Artificial systems  Artificial systems were the earliest systems, which attempted to classify organisms based on a few superficial characters.  Aristotle classified plants more than 2000 years ago on the basis of simple morphological characters into herb, shrub and trees.  Theophrastus in his book “Historia Plantarum or Enquiry into plants” attempted to arrange plants in various groups based on how plants reproduce and its uses. He is called “Father of Botany”.
 Carl Linnaeus is known as the “Father of Modern Taxonomy”.  In his book “Systema Naturae” (1735), he gave the hierarchical system of classification of the natural world into the plant kingdom, the animal kingdom and mineral kingdom.  He understood the importance of floral characters and classified plants based on the number of stamens present in them. It is also known as the sexual system of classification.  In “Species Plantarum” (1753), he gave a brief description of all the species known to him. He described around 7,300 plant species in it.  He gave the Binomial nomenclature system.  In “Philosophia Botanica”, he had given rules for naming every species. It is called binomial because each name has two components, genus name and species name, e.g. Solanum melongena (brinjal), Solanum tuberosum (potato) having the same genus but different species name.
Natural systems  In this system of classification, more characters were considered while classifying.  It was based on the natural similarities of vegetative and floral characters among the organisms.  It took into consideration various external and internal features like the anatomy of a cell, types of embryo and photochemistry.  Bentham and Hooker proposed the most important natural system of classification of flowering plants.  They classified plants into Cryptogams (non-flowering plants) Phanerogams (flowering plants)
Phylogenetic systems  This system is based on evolutionary sequence and genetic relationship.  This system was developed after the publication of Darwin’s theory of evolution.  Apart from the morphological characteristics found from fossil records, genetic constituents were also considered.  It has been widely accepted by biologists all over the world.  According to this system, all the organisms belonging to the same taxa originated from the common ancestor.
Importance of Plant Taxonomy  It gives a detailed overview of various morphological and anatomical structures of a plant species  It organizes all the information of plants into an orderly fashion  It indicates the phylogenetic relationship between species and its ancestry  Plant taxonomy enables to identify any unknown species and its place in the classification by comparing with known species  Analysis of genetic constituents can be done on the basis of systematics  It is used to scientifically name any species, which helps in the uniformity of the name around the world and avoids confusion  It helps to understand the biodiversity present at a place  It helps in recording all the living species known until now  Taxonomy is widely used in agriculture, medicine and forestry.
Modern/ Recent trends in taxonomy of flowering plants
1. Gross Morphological 2. Anatomical 3. Pollen Morphology or Palynological 4. Chemotaxonomy 5. Serotaxonomy 6. Palaeontological 7. Ontogenetical 8. Embryologyand Taxonomy 9. Numerical Taxonomy.
1. Gross Morphological • Turril says, the morphology, either of plants Or animals, now days includes a good deal more than the mere study of shape.  The term ‘morphology’ is very wide and includes anatomy, and much of cytology, ontogeny, embryology, paleontology and genetics.  He says, “even within morphology in a very strict sense the taxonomist is forced to consider matters which involve physiology.”  Turril says, that someone or other morphological classification provides the best basis for a general classification of the widest possible use, because morphological characters are, in general easier to use than others.
2. Anatomical  The study of morphology with a compound microscope is known as anatomy (histology).  According to some anatomists the anatomical features are more conservative than those of-gross morphology and are, therefore, of greater use in tracing phylogeny or organogenesis.  The following anatomical characters are of taxonomic significance:  Epidermal appendages, trichomes.  Structure of stomata.  The wood anatomy including the elements of the secondary xylem  The nodal anatomy of the axis, the leaf trace nature.  Floral anatomy.
3. Pollen Morphology or Palynological  The science of palynology or study of pollen morphology deals with the detailed study of pollen grains, i.e., the microspores of Spermatophyta, particularly of Angiosperms.  It mainly deals with the structure, walls, etc., of pollen grains.  Palynological studies help in the confirmation of relationship and affinities between the related taxa.
4. Chemotaxonomy  It is based on the classification of plants on the basis of their chemical constituents which are deeply concerned with the molecular characteristics.  The method of chemical taxonomy is simple in principle and is based on the investigation of the distribution of chemical compounds, or groups of biosynthetically related compounds in series of related plants.
5. Serotaxonomy:  Serotaxonomic test and consequent phylogenetic relationships between the taxa of angiosperms were established in Germany by Professor K. C. Mez (1866-1944) at the University of Koenigsberg in 1926, and this was modified in 1936.  He established that relationship between larger group of angiospermic plants could be determined by serological test; and the closely related taxa and plants could be arranged accordingly.  Serotaxonomy consists of the study and analysis of protein reaction of plants of different families with the blood serum of either rabbit or guineapig.
6. Palaeontological  Darrah has proposed the following palaeontological evidences in support of the phylogenetic evolution of the plants:  1. The invasion of land by an undifferentiated thalloid plant took place not later than Silurian.  2. The simple upright undifferentiated and protostelic axis formed in Silurian.  3. Enlargement of the plant body with specialization towards a division of labour-sterile and fertile, took place apparently in late Silurian.  4. Origin of the photosynthetic leaf took place in Devonian.
7. Ontogenetical  According to Gunderson the evolution of the flowering plants is based on floral structure and presumed organogenesis.  He points out that the flowering tendencies are widely accepted as progressive in organogenesis and agree with the findings in development.  Petals—from separate to united.  Petals—from actinomorphy to zygomorphy.  Sepals—from separate to united.  Ovary —from superior to inferior.  Carpels—from separate to united.  Placentation—from parietal to axile.
8. Embryology and Taxonomy  The comparative or phylogenetic embryology deals with the embryological data, which are used as a tool for ascertaining inter-relationships and taxonomic positions.  In a symposium on comparative Embryology of Angiosperms held at Delhi in 1967 the systematic positions of various families were discussed in the light of embryological data.  This symposium enabled to bring together in a comprehensive manner the scattered embryological literature on various families.
9. Numerical Taxonomy  It use mathematical principles for classifying the plants.  According to Sneath and Sokal (1973) “numerical taxonomy aims to develop methods that are objective, explicit and repeatable, both in evaluation of taxonomic relationships and in the erection of taxa.”  This science is based on evidence of similarities exhibited by observed and recorded characters of taxa, not on phylogenetic probabilities.  It is not concerned with producing new data but methods of handling them by means of electronic computers so as to reduce subjective element involved in comparing sets of data.
Description of flowering plants in botanical terms in relation to taxonomyNew Microsoft PowerPoint Presentation.pptx