Plant Kingdom: Classification

• Plant Kingdom: Classification and Characteristics

Hierarchy of Classification

• Ernst Haeckel proposed a 3 Kingdom Classification in 1864 and coined "Ecology" in 1866.
• Carl Linnaeus in 1735, gave a 2 kingdom classification
• Robert Whittaker in 1969, proposed 5 kingdoms: Monera, Protista, Fungi, Plantae, and Animalia.
• Carl Woese proposed 3 domains in 1997

Taxonomy

• Taxonomy is the science of describing, naming, and classifying all organisms.

Classification Groups (in order)

• Kingdom
• Phylum (animals)/Division (plants)
• Class
• Order
• Family
• Genus
• Species

General Classification

• Classification is based on: Prokaryote v/s Eukaryote cell structure, Unicellular/Multicellular organization, Modes of nutrition, and further classification into subgroups

Kingdom Monera

• Microscopic and Prokaryotic
• Examples: Archaebacteria, Eubacteria, Cynobacteria (Blue-green algae)
• Lacks a well-defined nucleus and membrane-bound organelles
• Cell wall may or may not be present
• Can be autotrophic/heterotrophic
• Archaebacteria: Mostly autotrophs, few are photosynthetic
• Eubacteria: Cell wall and plasma membrane are present, contains cytoplasm and Ribosomes

Kingdom Protista

• Unicellular eukaryotic organisms
• Locomotion through appendages
• Cell wall is absent (e.g., Euglena)
• Nutrition: Autotrophic/Heterotrophic
• Includes: Unicellular algae (diatoms) and protozoa

Phylum Protozoa

• Unicellular, mostly aquatic, solitary, or colonial
• Free-living, parasitic, or symbiotic
• Examples: Euglena, Amoeba, Paramecium, Plasmodium

Paramecium

• Uses cilia for movement and locomotion
• Cilia also helps move food to the oral cavity

Euglena

• Has a tail-like structure (flagellum) to help in cell movement

Amoeba

• Moves and captures food using pseudopods (false feet)

Kingdom Fungi

• Most are multicellular, except yeast
• Cell wall is present and made of complex sugar chitin
• May have a symbiotic relationship (e.g., Lichen = Blue-green algae + Fungi) where both benefit
• India's first lichen park is in Uttarakhand
• Colour change in lichen are due to global warming
• Used in medicine (Penicillin) and bakery (Yeast)
• Alexander Fleming discovered Penicillin (1st antibiotic)
• Mode of nutrition: Heterotrophic, Saprophytic (decays organic material as food), Parasitic (dependent on protoplasm)

Kingdom Plantae

• Multicellular and Eukaryotes
• Cell wall made up of cellulose is present
• Autotrophic and Sedentary

Kingdom Plantae Classification

• Based on differentiation of plant body, presence/absence of vascular tissues, ability to bear seeds, enclosure of seeds within fruits, and ability to produce flowers
• Plantae is split into Plants with and without differentiated body parts
• Plants with undifferentiated body parts are Thallophyta
• Differentiated plants are split based on vascular tissue

Angiosperms:

• Classified into monocots (one cotyledon) and dicots (two cotyledons)

Thallophyta

• Plants do not have well-differentiated body parts and are called algae
• Mostly aquatic (e.g., Spirogyra, Ulothrix, Ulva, and Chara)
• Eukaryotic, Non-motile, and Autotrophic
• No distinguished root, stem, or body
• Different pigments are present; some are edible and toxic

Bryophyta

• Known as "Amphibians of Plant Kingdom"
• Well-differentiated body with stem and leaves
• Root-like structures present (Rhizoids)
• Autotrophic and non-motile
• Found in damp and moist areas (e.g., Riccia, Moss (Funaria), Marchantia)
• Reproduction is through water
• Male part: Antheridium
• Female part: Archegonium

Pteridophyta

• First terrestrial plants
• Differentiated into roots, stem, and leaves
• Well-developed reproductive organs are hidden
• Specialized tissues for food and water conduction (vascular tissues are present)
• Leaves are made of leaflets that bear spores called Sporophylls
• Examples: Marsilea, fern, Horsetails

Cryptogams vs. Phanerogams

• Cryptogams: Seeds/flowers/fruits are absent, reproductive organs are hidden, less evolved plants (thallophytes, bryophytes, pteridophytes)
• Phanerogams: Seeds/flowers/fruits are present, reproductive organs are exposed, highly evolved plants (Gymnosperm, Angiosperm)

Gymnosperms

• Gymno: Without cover
• Sperma: Seeds without fruit - Primitive and simple seeds
• Usually perennials, evergreen, and mostly woody plants
• True roots, stem, and leaves are present
• Xylem vessel absent
• Examples: Pinnes and Deodar, Cycas

Angiosperms

• Angio: Covered
• Sperma: Seed
• Flowering plants with seeds enclosed in fruit
• Highly evolved
• Ovary modifies into fruit
• Seeds have an embryo inside that develop inside the ovary
• Embryos have structure called Cotyledons (seed leaves)
• The ovary becomes a fruit, earlier ovules become seeds