PLANT CLASSIFICATION AND SYSTEMATICS

PLANT CLASSIFICATION AND SYSTEMATICS

DEFINITIONS

Plant Taxonomy or Taxonomy

  • The science that finds, identifies, describes, classifies, and names different plants.

  • Coined by Augustin Puramus de Candolle in 1813.

Taxonomy vs. Systematics

  • Taxonomy: Focuses on methods and principles of classification, including naming and describing plants.

  • Systematics (Biosystematics): Broader field including taxonomy, evolutionary processes, and phylogeny studies.

Taxonomists

  • Scientists specializing in classification and naming of species, emphasizing evolutionary relationships in naming conventions.

GOALS OF PLANT SYSTEMATICS

  • Plant Identification: Recognizing and naming species. ( ma identify kung anong plant siya )

  • Plant Classification: Organizing plants into hierarchical categories. ( kung anong group ng plant siya belong )

  • Plant Description: Detailing characteristics of different species. ( gumagawa na ng scientific report/paper )

HISTORY OF PLANT SYSTEMATICS

  • Late 19th century: (1) Development of natural classification systems correlating closely related organisms. (2) assigning plant names on the basis of phylogenetic relationship.

  • Key milestones:

    • 1866: John Hogg and Ernst Haeckel propose the concept of Protoctista.

    • 1969: Whittaker introduces the 5-kingdom system.

    • 1990: Concepts of kingdoms Archaebacteria, Archezoa, Chromista, and Protista arise.

  • Modern taxonomy started in mid-1700s with Carolus Linnaeus's Systema Naturae, outlining his new and revolutionary method for classifying and, especially, naming living organisms.

  • The goal of modern plant systematics is to understand each of these evolutionary lines and to have a system of names or nomenclature that reflects their relationships accurately.

  • Every species had both a genus name and a species plant epithet, the basis of our present binomial system of nomenclature

TYPES OF CLASSIFICATION SYSTEMS

Cladistics

  • Refers to a biological classification system that involves the categorization of organisms based on shared traits.

Plesiomorphy

  • Ancestral traits retained through evolution; can share these traits (symplesiomorphies).

Apomorphology

  • Derived states defining specific clades, which include

    • Autapomorphies: Traits that are exhibited only by one species or group

    • Synapomorphies: Refers to entire clades which can be classified by the presence of a particular trait

Homoplasy

  • Shared traits among organisms that do not arise from a common ancestor, due to convergence or evolutionary reversal.

Artificial Systems of Classification

  • Based on easy-to-observe key characteristics.

    • Examples of classifications include:

      • Based on Type of Nutrition: Autotrophic Plants and Heterotrophic plants.

      • Based on Water Requirement: Mesophytes, Xerophytes, Hydrophytes, Halophytes.

      • Based on Habitat: Aquatic, Terrestrial, Aerial plants.

      • Based on Body Appearance: Trees, Shrubs, Herbs, Vines.

      • Based on Life Span: Annuals, Biennials, Perennials.

LEVELS OF TAXONOMIC CATEGORIES

  • Kingdom: Plantae

  • Division: Magnoliophyta

  • Class: Liliopsida (Monocots), Magnoliopsida (Dicots)

  • Order: Liliales, Fabales

  • Family: Liliaceae, Fabaceae (Leguminosae)

  • Genus: Hymenocaulis, Lupinus

  • Species: Hymenocaulis texensis, Lupinus caribaea

  • Scientific names follow binomial form: Genus + Species epithet.

EXAMPLES OF TAXONOMIC CATEGORIES

  • Corn:

    • Kingdom: Plantae

    • Division: Tracheophyta

    • Class: Magnoliopsida

    • Order: Poales

    • Family: Poaceae

    • Genus: Zea L.

    • Species: Zea mays L.

HIERARCHY OF BIOLOGICAL CLASSIFICATION

  • Species

  • Genus

  • Family

  • Order

  • Class

  • Phylum

  • Kingdom