Kerala PSC - Study Material :Biology(Classification of Plant Kingdom)

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• Plant Kingdom is broadly divide into two Cryptogamae and Phanerogamae.
• Cryptogams are flowerless and seedless plants whereas Phanerogams are flowering plants.
• Cryptogams are again divided into Thallophyta, Bryophyta and Pteridophyta.
• Thallophyta includes Algae, Fungi and Lichens
• Bryophytes are called "Amphibians of the plant kingdom".
• Bryophytes have no vascular tissue for conduction of water and food. They lack true roots, stem and leaves.
• Pteridophytes are the highest group in cryptogams. They are land plants that grow well in moist, shady and cool places. They have true root, stem and leaes. e.g, Dryopteris, Adiantum etc.
• Phanerogams are divided into two: Gymnosperms and Angiosperms.
• Gymnosperms are primitive flowering plants. Seeds are not enclosed in fruits. e.g, Pinus, Cycas, Cedrus.
• Angiosperms : More advanced flowering plants with well developed vascular tissues.
• They range in size from minute - floating duck weeds to giant eucalyptus and silk - cottom trees, and include plants of a great variety of forms - cacti, water lilies, sunflowers, orchids, pitcher plants, Indian pipe, etc.
• Flowering plants are divided into two classes -
1. Dicotyledons (Dicots), Monocotyledons (monocots).
• Dicotyledons : These plants have two cotyledons in their seeds eg., hard wood trees, pulses, most fruits and vegetables many spices, beverages crops and many ornamental crops.
• Monocotyledons : They have only one cotyledon in their seeds. e.g., Cereals, Bamboo, Sugarcane, banana, palms, lilies, orchid.
• On the basis of morphology, angiosperms are further classified into
1. Herbs
2. shrubs
3. trees
• Herbs are small plants with a soft stem.
• Medium sized plants with woody stems and branches are called Shrubs.
• Trees have tall, woody, stout trunk with profuse branching.
• On the basis of age, they are grouped as Annuals, biennials and perennials.
• Plants which complete their life cycle within one season are termed Annuals. e.g. rice, groundnut.
• Plants that complete their life cycle in two seasons are termed Biennials. e.g., radish, cabbage
• Plants that usually survive for a number of years and produce flowers and fruits during specific seasons are termed Perennials. e.g., mango, coconut, apple etc.