Plant Kingdom Notes 🌿

🌱 Mosses

• Life Cycle: Gametophyte is the main stage
  • Stage 1: Protonema (creeping green filaments from spores)
  • Stage 2: Leafy stage (upright stems with spiral leaves)
• Reproduction:
  • Vegetative: Fragmentation/budding in protonema
  • Sexual: Antheridia (♂) & archegonia (♀) at shoot tips → Zygote → Sporophyte (foot + seta + capsule)
• Fun Fact: Moss sporophytes have special capsules for spore dispersal 💨
• Examples: Funaria, Polytrichum, Sphagnum

🌿 Pteridophytes (Ferns & Horsetails)

• Uses: Medicine, soil-binders, and decoration 🏡
• Habitat: Cool, damp, shady places
• Evolutionary Milestone: First plants with vascular tissues (xylem & phloem)!
• Plant Body: Sporophyte dominant
  • Leaves: Microphylls (small, e.g., Selaginella) or Macrophylls (large, e.g., ferns)
  • Sporangia: On leaf-like sporophylls (sometimes form cones 🎋)
• Reproduction:
  1. Spores (from meiosis) → Prothallus (tiny photosynthetic gametophyte)
  2. Prothallus needs water & shade to survive 💧
  3. Antherozoids (♂) swim to archegonia (♀) → Fertilization → New sporophyte
• Spore Types:
  • Homosporous: One spore type (most pteridophytes)
  • Heterosporous: Two spore types (Selaginella, Salvinia):
    • Megaspores → Female gametophytes
    • Microspores → Male gametophytes
• Key Innovation: Retention of female gametophyte → Evolutionary step toward seeds! 🌱
• Classification:

  Class	Examples
  Psilopsida	Psilotum
  Lycopsida	Selaginella, Lycopodium
  Sphenopsida	Equisetum (horsetails)
  Pteropsida	Dryopteris, Pteris (ferns)

🌲 Gymnosperms (Naked Seeds)

• Seeds: Not covered by ovary (exposed before/after fertilization)
• Examples: Medium/tall trees (e.g., Sequoia – world’s tallest tree 🌲), shrubs
• Cool Adaptations:
  • Roots: Tap roots; some with fungal partners (Pinus) or N₂-fixing bacteria (Cycas)
  • Leaves: Needle-shaped → Less surface area + thick skin + hidden pores → Saves water! 💧

💡 NEET Must-Knows

1. Pteridophytes = First vascular plants (xylem/phloem)
2. Heterospory → Key step toward seeds (e.g., Selaginella)
3. Dominant stages:
   • Bryophytes: Gametophyte
   • Pteridophytes: Sporophyte
4. Water essential for fertilization in pteridophytes (sperm swims!)
5. Gymnosperm seeds = naked (no fruit covering)