Seeds & Plant Description Notes 🌱✨

5.7 What is a Seed?

  • Seeds develop from fertilized ovules 🌼→🌰
  • Every seed has:
    • Seed coat (protective outer layer)
    • Embryo (baby plant inside)
  • The embryo contains:
    • Radicle (will become root)
    • Embryonal axis (main stem part)
    • Cotyledons (seed leaves 🌿 – 1 in maize, 2 in peas)

5.7.1 Dicot Seeds (e.g., beans, gram)

  • Seed coat has 2 layers:
    • Outer: Testa
    • Inner: Tegmen
  • Special marks on seed coat:
    • Hilum – scar where seed attached to fruit
    • Micropyle – tiny pore above hilum
  • Embryo has two fleshy cotyledons storing food 🥑
  • Radicle + Plumule at ends of embryonal axis (plumule becomes shoot)
  • Two types:
    • Endospermic (e.g., castor): Has food-storing endosperm tissue
    • Non-endospermous (e.g., bean/gram): No endosperm in mature seed

5.7.2 Monocot Seeds (e.g., maize)

  • Usually endospermic (stores food in endosperm) 🌽
  • Seed coat fused with fruit wall
  • Aleurone layer separates embryo from endosperm (protein-rich!)
  • Embryo has:
    • One shield-shaped cotyledon (called scutellum)
    • Plumule covered by coleoptile (sheath)
    • Radicle covered by coleorhiza (sheath)

5.8 Describing Flowering Plants 🌸

  • Describe in this order:
    1. Habit (plant shape/size)
    2. Vegetative parts: Roots → Stem → Leaves
    3. Floral parts: Inflorescence → Flower details
  • Use floral formula with symbols:
    • \( \mathbf{Br} \) = Bracteate
    • \( \mathbf{K} \) = Calyx
    • \( \mathbf{C} \) = Corolla
    • \( \mathbf{P} \) = Perianth
    • \( \mathbf{A} \) = Androecium
    • \( \mathbf{G} \) = Gynoecium
    • \( \underline{\mathbf{G}} \) = Superior ovary
    • \( \overline{\mathbf{G}} \) = Inferior ovary
    • \( \overrightarrow{\mathcal{O}} \) = Male plant
    • \( \overrightarrow{\mathcal{Q}} \) = Female plant
    • \( \oplus \) = Actinomorphic (radial symmetry) ⭐

🌟 Important for NEET 🌟

  • Dicot vs. monocot seeds (cotyledon number, endosperm presence)
  • Seed parts: Hilum, micropyle, testa, tegmen, radicle, plumule
  • Monocot seed specials: Scutellum, coleoptile, coleorhiza
  • Floral formula symbols (especially \( \mathbf{G} \), \( \underline{\mathbf{G}} \), \( \oplus \))
  • Endospermic vs. non-endospermic seeds (examples: castor vs. gram)