Short Notes Plant Kingdom - Short Notes for NEET PDF Download

Classification of Plants

• Cryptogamae: Hidden reproduction; no seeds (Algae, Bryophytes, Pteridophytes)
• Phanerogamae: Visible seeds (Gymnosperms, Angiosperms)

Algae

Classification of Algae

Economic Importance:

• Primary producers in aquatic ecosystems
• Agar: Gelidium, Gracilaria (culture medium)
• Algin: Laminaria, Fucus (ice cream, paints)
• Carrageenan: Rhodophyceae (food industry)
• Iodine: Laminaria, Fucus
• Food: Porphyra, Laminaria, Sargassum
• Chlorella, Spirulina: Single Cell Protein (SCP)

Bryophytes (Amphibians of Plant Kingdom)

• Non-vascular; moist, shady habitats
• No true roots, stem, leaves (root-like: rhizoids)
• Plant body: gametophyte (haploid, dominant, photosynthetic)
• Sex organs: Antheridia (male), Archegonia (female) - multicellular, jacketed
• Water essential for fertilization (zooidogamy)
• Zygote → Sporophyte (diploid, dependent on gametophyte)
• Sporophyte: foot, seta, capsule (sporangium)
• Spores → germination → gametophyte

Classification:

Economic Importance:

• Ecological importance: soil formation, moisture retention
• Sphagnum: Peat (fuel), packing material, antiseptic in surgery

Pteridophytes (First Vascular Plants)

• Characteristics:
  • Vascular tissue present (xylem + phloem)
  • True roots, stem, leaves
  • Dominant phase: Sporophyte (diploid, independent, photosynthetic)
  • Leaves: Microphylls (small, unbranched vein) or Macrophylls (large, branched veins)
  • Sporophylls: leaf-like structures bearing sporangia (compact = strobili/cones)
  • Homosporous: One type of spore (e.g., Pteris) OR Heterosporous: Two types - microspores (male) + megaspores (female) (e.g., Selaginella, Salvinia)
  • Spore → germination → gametophyte (prothallus: small, multicellular, photosynthetic)
  • Gametophyte bears antheridia and archegonia; water needed for fertilization
• Classification:

  Class	Features	Examples
  Psilopsida	Rootless; simple sporophyte	Psilotum
  Lycopsida	Microphylls; terminal sporangia on sporophylls	Selaginella, Lycopodium
  Sphenopsida	Jointed stem; whorled leaves; homosporous	Equisetum (horsetail)
  Pteropsida	Macrophylls; most common ferns	Pteris, Adiantum, Marsilea, Azolla, Salvinia

• Economic Importance:
  • Ornamental plants
  • Medicinal (Male fern - anthelmintic)
  • Soil binders, food (some in tribal areas)

Gymnosperms (Naked Seeds)

• Characteristics:
  • Seeds not enclosed in fruit (naked seeds)
  • Mostly perennial, evergreen, woody trees/shrubs
  • Tap root system with coralloid roots (Cycas: cyanobacteria symbiosis)
  • Leaves: needle-like (reduce water loss) or compound (Cycas)
  • Sporophylls arranged in cones/strobili
  • Heterosporous: Male cones (microsporophylls with microsporangia) and Female cones (megasporophylls with ovules)
  • Pollen grains directly on ovules (pollination)
  • No archegonia in some (e.g., Gnetum)
  • Seeds with haploid endosperm (formed before fertilization)
  • Xylem: Only tracheids; Phloem: No companion cells
• Classification:

  Class	Features	Examples
  Cycadopsida	Unbranched stem; pinnate compound leaves; dioecious	Cycas
  Coniferopsida	Tall trees; needle-like leaves; monoecious or dioecious; woody cones	Pinus, Cedrus (deodar), Abies (fir)
  Ginkgopsida	Fan-shaped leaves; dioecious; living fossil	Ginkgo biloba
  Gnetopsida	Vessels in xylem; closest to angiosperms	Gnetum, Ephedra

• Economic Importance:
  • Timber (Pinus, Cedrus)
  • Paper pulp (softwood)
  • Resin, turpentine (Pinus)
  • Ornamental (Cycas, Thuja, Araucaria)
  • Food (Cycas seeds: sago after detoxification)

Angiosperms (Flowering Plants)

• Characteristics:
  • Seeds enclosed in fruit (covered seeds)
  • Most diverse group (~250,000 species)
  • Range: microscopic (Wolffia) to tall trees (Eucalyptus ~100m)
  • All habitats: terrestrial, aquatic, parasites, epiphytes, desert
  • Reproductive organ: Flower
  • Double fertilization: unique feature
  • Triploid endosperm (formed after fertilization)
  • Seeds enclosed in fruit
  • Xylem: vessels + tracheids; Phloem: sieve tubes + companion cells
• Classification:

  Feature	Dicotyledons	Monocotyledons
  Cotyledons	Two	One
  Root system	Tap root	Fibrous root
  Leaf venation	Reticulate	Parallel
  Flower parts	Multiples of 4 or 5	Multiples of 3
  Vascular bundles	Arranged in ring, open (with cambium)	Scattered, closed (no cambium)
  Secondary growth	Present	Absent (except in palms)
  Examples	Pea, Mustard, Rose, Sunflower	Wheat, Maize, Rice, Onion, Lily

• Economic Importance:
  • Food: cereals, pulses, vegetables, fruits, oils, spices
  • Timber, paper, fibers (cotton, jute)
  • Medicines, beverages (tea, coffee)
  • Ornamental plants

Plant Life Cycles - Summary