Binomial System of Nomenclature

• Theophrastus, 4^th Century B.C.
  • classification of 500 known species
• 13^th Century A.D.
  • classified as Monocots or Dicots, based on stem structure
  • "numerous" species added
  • species "named" as Latin phrases describing plant
    first word indicated Genus (plural = "Genera")
    • Mint [Mentha] with flowers in a spike; leaves oblong, saw-toothed
      common name: spearmint
    • Mint [Mentha] with terminal flowers; leaves lance-shaped, saw-toothed
      common name: peppermint
  • 18^th Century
    • added fruit and flower characteristics to classification
    • world exploration produced 1,000's of new species
    • classification system became overwhelmed, and cumbersome
  • Linnaeus, 1753. Species Plantarum
    • listed all known plant species, with two word name [Genus species]
      plus Latin descriptive name [limited to 12 words]
    • two-word [binomial] name is now standard
      with Latin description as the official definition of the species
    • formal references to a species also includes the 'name' of the scientist [abbreviated for 'famous' botanists] who first described the species.
      • spearmint is Mentha spicata L. [for Linnaeus]
      • peppermint is M. piperita L.
    • all known species were classified into 24 "classes"
      based on superficial similarities
  • 1867 International Code of Botanical Nomenclature established
    • rules for naming new species:
      • publish binomial name and Latin description
      • reference type specimen, an annotated herbarium specimen
        stored in a stated Herbarium
    • Index Kewensis list of all recognized species

  Classification System

  • taxon [plural = 'taxa'] = standard classification unit
    • species [plural = 'species']
    • Genus [plural = 'genera']
    • Family [plural = 'families']
    • Order [plural = 'orders']
    • Class [plural = 'classes']
    • Phylum [plura = 'phyla']
      older botanical references use "Division" [plural = 'divisions']
    • Kingdom [plural = 'kingdoms']
  • non-standard taxa:
    • form [often merely a single gene difference]
    • variety
    • subspecies
    • species
    • subgenus
    • genus
    • supergenus
    • subfamily
    • family
    • superfamily
    • suborder
    • order
    • superorder
    • subclass
    • class
    • subphylum
    • phylum
    • Kingdom
    • Domain [proposed taxa above the Kingdom level]
      • Archaea
      • Bacteria
      • Eucarya
  • "Traditional" (Linnaean) system recognizes 2 Kingdoms
    • 1969. Whittaker proposed 5 Kingdom system
    • 1980s. Woese et al. proposed 6 Kingdom system
    • other, more complicated systems have been proposed; but are not accepted
  
  

  	KINGDOMS
  organism	2	5	6
  Archaebacteria	Plantae	Monera	Archaea
  true Bacteria			Bacteria
  Algae		Protista	Protista
  Slime molds
  Water molds
  Protozoa
  Sponges
  true Fungi	Plantae	Fungi	Fungi
  Bryophytes		Plantae	Plantae
  Vascular Plants
  Protoza	Animalia
  Sponges
  Multicellular animals		Animalia	Animalia

  theoretical considerations

  • systematics
    • systematic collection of data on similarities
    • organization of taxa to reflect these similarities
  • phylogeny
    • intent is to describe evolutionary relationships among taxa
    • based on [qualitative] similarities in inheritable traits
  • cladistics
    • attempt to quantify differences between taxa
      • 'quantify' similarities in [inheritable] traits
      • estimate similarities in DNA by DNA-hybridization
      • estimate similarities in DNA by genome sequencing

  Identification Keys

  • normally written as dichotomous keys
  • series of paired statements describing characteristics of organisms
  
  

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