Topics to be learn :

  • Kingdom Plantae
  • Sub-kingdom – Gymnosperms
  • Sub-kingdom – Angiosperms

Classification of Plants

Introduction to Classification

  • Classification categorizes things based on properties.
  • Organisms grouped by common features.

Robert Whittaker's Five Kingdom System (1959)

  • Five kingdoms: Monera, Protista, Fungi, Plantae, Animalia.

Botanist Eichler's Classification (1883)

  • Kingdom Plantae divided into: Cryptogams, Phanerogams.

Basis for Classification

  • Presence or absence of organs.
  • Presence or absence of separate conducting tissues.
  • Presence or absence of seeds.
  • Seeds enclosed in fruits or not.
  • Number of cotyledons in seeds: one or two.

Criteria for Plant Classification

  • Flowering plants divided into gymnosperms and angiosperms.
  • Non-flowering plants are non-seed-bearing.
  • Thallophyta lack roots, stem, leaves.
  • Vascular plants have conducting tissues.
  • Non-vascular plants lack vascular tissues.
  • Seed-bearing vs. non-seed-bearing plants.
  • Gymnosperms vs. angiosperms based on seeds in fruits.
  • Dicotyledons vs. monocotyledons based on cotyledons.

Sub-kingdom: Cryptogams (Reproduce via spores)

Division I - Thallophyta:

Habitat Mainly water habitats, Freshwater and marine environments.

Structure

  • Lack specific parts: root, stem, leaves, flowers.
  • Autotrophic: contain chlorophyll.
  • Algae: diverse, unicellular or multicellular.
  • Sizes: microscopic to macroscopic.
Examples: Unicellular: Spirogyra, Ulothrix, Multicellular: Ulva, Chara, Sargassum.
  • Fungi in Thallophyta: Types: yeasts, molds, Chlorophyll absence.
  • Chloroplasts Found in plant cells, not animal cells, Enable photosynthesis.

Spirogyra:

  • Description: Green filamentous alga, Freshwater habitat.
  • Function Photosynthesis: synthesizes food.
  • Structure Chlorophyll presence, Thread-like chloroplasts, Contain pyrenoids.

Division II - Bryophyta:

Habitat: Moist soil, requires water for reproduction.

Structure

  • Mostly thalloid, some mosses.
  • Multicellular, autotrophic.
  • Flat, ribbon-like body.
  • Lack true roots, have rhizoids.
Examples: Funaria (moss), Riccia, Marchantia.


Marchantia: (Bryophyte)

  • Amphibious: soil for growth, water for reproduction.

Structure

  • Flat, ribbon-like.
  • Lacks true roots, stems, leaves.
  • Rhizoids instead of roots.
  • No conducting tissues.

Division III - Pteridophyta:Structure
  • Well-developed roots, stems, leaves.
  • Lack flowers and fruits.
  • Conducting tissues present.
  • Reproduce via spores.
Examples: Nephrolepis, Adiantum, Pteris.

Ornamental Plants:
  • Description: Seen in gardens, For aesthetic purposes.
  • Features: No flowers or fruits, Attractive leaves, Reproduce via spores in sori.

Sub-kingdom - Phanerogams:

Characteristics
  • Flowers, fruits, seeds present.
  • Further classified: gymnosperms, angiosperms.

Gymnosperms:Description
  • Perennial, woody, evergreen.
  • Unbranched stems.
  • Leaves form crown.
  • Male and female flowers on separate sporophylls.
  • Seeds naked.
Examples: Cycas, Thuja, Picea, Pinus.

Angiosperms:Description
  • Seeds enclosed in fruits.
  • Possess roots, stems, leaves.
  • Flowers as reproductive organs.
Classification:Monocots, dicots based on cotyledons.

Difference between Monocot and Dicot:

Hibiscus (A dicot plant):

  • Root: Tap root.
  • Stem: Erect, branched.
  • Leaf: Simple, alternate, reticulate venation.
  • Flower
  • Pedicillate, complete, bisexual.
  • Sepals: 5, fused.
  • Petals: 5, fused.
  • Stamens: indefinite, fused into staminal tube.
  • Pistil: 5 carpels fused.

Onion (Allium cepa) (A monocot plant):

  • Description: Small herb with tunicated bulb.
  • Root: Fibrous.
  • Stem: Underground stem (bulb).
  • Leaves: Hollow, tubular.
  • Flower
  • Complete, bisexual.
  • Perianth: 6 lobes in two whorls of 3 each.
  • Stamens: 6, epiphyllous.
  • Pistil: 3 carpels fused, superior ovary.

Maize (Monocotyledonous plant):

  • Single cotyledon in seed.
  • Fibrous roots, hollow false stem.
  • Leaves with parallel venation.
  • Flowers with trimerous symmetry.