The Plant Kingdom includes all autotrophic, multicellular, eukaryotic organisms that perform photosynthesis. Plants are essential for life as they:
- Produce oxygen
- Act as primary producers
- Maintain ecological balance
Plants show a wide range of diversity—from simple algae to complex flowering plants.
Basis of Classification
Plants are classified based on:
- Body organization (thallus or differentiated body)
- Vascular tissues (xylem and phloem)
- Reproduction (spores or seeds)
- Presence of flowers
- Seed type (naked or enclosed)
Classification of Plant Kingdom
Plants are divided into five major groups:
- Algae
- Bryophytes
- Pteridophytes
- Gymnosperms
- Angiosperms
1. Algae
Characteristics:
- Mostly aquatic
- Simple thalloid body
- No differentiation into root, stem, leaf
- Photosynthetic
Types of Algae
1. Chlorophyceae (Green Algae)
- Pigment: Chlorophyll a & b
- Store food as starch
Examples: Spirogyra, Chlamydomonas
2. Phaeophyceae (Brown Algae)
- Pigment: Fucoxanthin
- Store food as laminarin
Examples: Sargassum, Laminaria
3. Rhodophyceae (Red Algae)
- Pigment: Phycoerythrin
- Store food as floridean starch
Examples: Gelidium, Polysiphonia
2. Bryophytes (Amphibians of Plant Kingdom)
Characteristics:
- Mostly terrestrial
- Require water for reproduction
- Lack vascular tissues
- Dominant gametophyte
Types:
- Liverworts (Marchantia)
- Mosses (Funaria)
Importance:
- Soil formation
- Prevent soil erosion
3. Pteridophytes
Characteristics:
- First vascular plants
- True roots, stems, and leaves present
- Reproduce via spores
Examples:
- Fern
- Equisetum
Life Cycle:
- Sporophyte dominant
- Gametophyte small and independent
4. Gymnosperms
Characteristics:
- Naked seeds (not enclosed in fruit)
- Vascular plants
- Mostly woody
Examples:
- Pinus
- Cycas
Key Features:
- Cones present
- Pollination by wind
5. Angiosperms (Flowering Plants)
Characteristics:
- Seeds enclosed in fruits
- Presence of flowers
- Double fertilization
Types of Angiosperms
1. Monocots
- One cotyledon
- Parallel venation
- Fibrous roots
2. Dicots
- Two cotyledons
- Reticulate venation
- Tap root system
Plant Life Cycles
Plants show alternation of generations:
1. Haplontic
- Dominant haploid phase
2. Diplontic
- Dominant diploid phase
3. Haplodiplontic
- Both phases multicellular
Important Differences
Bryophytes vs Pteridophytes
| Feature | Bryophytes | Pteridophytes |
|---|---|---|
| Vascular tissue | Absent | Present |
| Dominant phase | Gametophyte | Sporophyte |
Gymnosperms vs Angiosperms
| Feature | Gymnosperms | Angiosperms |
|---|---|---|
| Seeds | Naked | Covered |
| Flowers | Absent | Present |
Important NEET & CBSE Points
- First vascular plants: Pteridophytes
- Amphibians of plant kingdom: Bryophytes
- Naked seeds: Gymnosperms
- Double fertilization: Angiosperms
- Dominant phase in bryophytes: Gametophyte
Quick Revision Notes
- Algae → aquatic
- Bryophytes → no vascular tissue
- Pteridophytes → vascular
- Gymnosperms → naked seeds
- Angiosperms → flowers
Frequently Asked Questions (FAQs)
Q1. Why are bryophytes called amphibians?
Because they live on land but require water for reproduction.
Q2. What are gymnosperms?
Plants with naked seeds.
Q3. What is double fertilization?
Fusion of two male gametes with female gametes in angiosperms.
Q4. Which plants have vascular tissues?
Pteridophytes, gymnosperms, and angiosperms.
Conclusion
The Plant Kingdom showcases a gradual evolution from simple to complex organisms. Understanding these groups helps in grasping plant diversity and evolution—making this chapter highly important for CBSE exams and NEET preparation.