Exam Capsule Quick Revision Notes- Plant Systematics Short Notes

An attempt to classify organisms based on overall similarity, usually in morphology or other observable traits, regardless of their phylogeny or evolutionary relationship is called Taximetrics.

  • The term alpha diversity refers to Community and ecosystem diversity.
  • The diversity within a particular area or ecosystem
  • Numerical taxonomy is otherwise called Phenetics
  • Alpha diversity: The diversity within a particular area or ecosystem
  • Beta diversity refers to between habitat diversity.
  • The diversity of habitats over the total geographical area is Gama diversity.
  • Rule of priority of ICBN states that the earliest applicable, properly published name is the correct one.
  • Symbiotic origin of mitochondria and chloroplasts has been confirmed by Molecular taxonomy.
  • The symbiotic origin of mitochondria and chloroplasts has been confirmed by Molecular taxonomy
  • Kingdom-Phylum-Class-Order-Family-Genus-Species
  • Monophyletic group includes all descendant species of a single ancestor and the ancestor species itself.
  • taxonomic clade considers Monophyletic groups alone
  • A group of organisms is said to be paraphyletic, if all the members of the group have a common ancestor, but the group does not include all the descendants of the recent common ancestor.
  • Taxonomic groups that contain organisms, which are descendants of more than one ancestor are called polyphyletic group.
  • Archae domain eukaryotes derived
  • Linnaeus: 2 kingdoms
  • Chatton: 2 empires
  • The three domain system were proposed by Carl Woese
  • The five kingdom classification proposed by Robert Whittaker
  • Monera Kingdom of Whittaker’s five kingdom system of classification that includes the blue-green algae, nitrogen fixing bacteria and methanogenic archaebacteria.
  • Cavalier smith- 8 kingdom classification
  • Numerical Taxonomy is otherwise called as Adansonian classification.
  • Homonyms : Identical names for 2 or more different taxa
  • Species : A group of interbreeding natural populations that are reproductively isolated from other such species.
  • Gene flow is a concept best used to describe an exchange between  Populations
  • Taxon: A group of organisms with common ancestor and with concrete biological objects of classification worthy of being assigned to a definite category in the hierarchical classification.
  • Bacteria are classified mainly on biochemical and genetic characters.
  • Main application of phenetics is in classifying organisms.
  • The basic unit of numerical taxonomy is called OTU
  • illegitimate name:  Superfluous name , Later homonyms ,Tautonyms
  • A nomennudum is a name: Without a description
  • Date of the starting point of zoological nomenclature as fixed by the ICZN -1 January 1758
  • In disputes concerning homonyms, according to the ICZN rules, The ‘senior’ homonym can be replaced with the ‘junior’ homonym if it is scientifically more valid and appropriate
  • Chloroplast based DNA markers are now being used for the taxonomic identification of plants. This method is called DNA barcoding
  • The concept of DNA barcoding for molecular taxonomy of eukaryotes depends on Analyses of mitochondrial cytochrome oxidase gene sequences.
  • matK in plants and COI in animals are widely used for barcoding in plants and animals


Binomial Nomenclature

  • The same name is used in all languages avoiding difficulty of translation.
  • The system has been adopted internationally in Botany, Zoology and Bacteriology.
  • Every species can be unambiguously identified with just two words

Books and Authors

  • Systema Naturae - Carolus Linnaeus
  • Flora Lapponica is written by Carolus Linnaeus
  • The seven volumes of the “Flora of British India “was compiled by J D Hooker
  • Dioscorides wrote the book "De Materia Medica", which was a catalog of about 600 plants in the Mediterranean


  • Natural system of classification- Bentham and Hooker Classification
  • Artificial- Linnaeus System of classification
  • Phylognetic System of Classification

Bentham and Hooker system ofclassification

Merit : 

  • Placement of monocots after the dicots


  • Placement of Aseraceae in the beginning of gamopetae
  • Placement of Gymospermae in between dicots anad monocots.
  • Placement of family Orchidaceae in the beginning of monocts

In DNA barcode analysis for molecular taxonomy, the material recommended for taxonomical studies in prokaryotes is 16S RNA

Demerits of Engler and Prantl systemof classification

  • Derivation of parietal placentation from axile placentation.
  • Derivation of bisexual flower from unisexual flower.
  • Derivation of entomophily from anemophily.


  • When a single specimen is clearly designated in the original description, this specimen is known as: Holotype
  • In the typification, the specimen designated from the original material as the nomenclatural type, in conformity with Art. 9.9 and 9.10, if no holotype was indicated at the time of publication, or if it is missing, or if it is found to belong to more than one taxon is known as Lectotype
  • A specimen selected from the original material to serve as a nomenclatural type when no holotype was designated at the time of publication is called Lectotype
  • Species with wide geographical ranges of distribution, that develop locally adapted populations are known as Ecotypes
  • When a specific epithet exactly repeats the generic name it is known as Tautonym
  • Ideo type is a biological model which is expected to perform or behave in a predictable manner within a defined environment.

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