Comprehensive Notes on Morphology of Flowering Plants

Root System and Functions

  • Core Functions: Absorption of water/minerals, anchorage, storage of food, and synthesis of plant growth regulators (PGR).
  • Taproot System: Present in Gymnosperms and Dicot Angiosperms (e.g., Mustard).
  • Fibrous Root System: Characteristic of Monocot Angiosperms.
  • Adventitious Roots: Roots arising from parts other than the radicle (e.g., Sweet Potato).
  • Velamen Roots: Found in epiphytic plants like orchids (e.g., Vanda); contain hygroscopic epithem tissue for water absorption.

Parts of the Root and Modifications

  • Root Regions:
    • Root Cap: Protects the tender tip.
    • Meristematic Activity: Rapid cell division for growth.
    • Region of Elongation: Responsible for root length.
    • Region of Maturation: Epidermal cells form root hairs for absorption.
  • Storage Modifications:
    • Conical: Carrot (Daucus Carota).
    • Fusiform: Radish (Raphanus Sativus).
    • Napiform: Beetroot and Turnip.
  • Respiratory Roots: Pneumatophores found in swampy regions with small openings called pneumathodes for gas exchange.

Stem Structure and Modifications

  • General Functions: Conduction of water/minerals, photosynthesis, storage, and vegetative propagation.
  • Underground Storage: Potato (Solanum tuberosum), Ginger, Turmeric, Zaminkhand, and Colocasia (organs of perennation).
  • Support and Protection:
    • Stem Tendrils: From axillary buds; assist climbing (e.g., Cucumber, Watermelon, Grapevines).
    • Thorns: Woody, pointed axillary buds for protection (e.g., Bougainvillea, Citrus).
  • Photosynthetic Stems: Found in arid regions; flattened in Opuntia and cylindrical in Euphorbia.
  • Vegetative Spread: Runners in Grass/Strawberry; Stolons in Mint/Jasmine; Offsets in Eichhornia/Pistia; Suckers in Banana/Pineapple.

Leaf Morphology

  • Main Parts: Leaf base (may include a swollen pulvinus in legumes), Petiole (holds blade to light), and Lamina (blade).
  • Types of Leaves:
    • Simple: Lamina incision does not touch the midrib.
    • Compound: Incisions reach the midrib dividing it into leaflets. Includes Pinnately (leaflets on a rachis) and Palmately (leaflets at petiole tip).
  • Modifications: Tendrils (Pea), Spines (Cacti), Storage (Onion/Garlic), and Phyllodes (Australian Acacia).
  • Insectivorous Leaves: Pitcher plant and Venus’s fly trap.

Flower and Inflorescence

  • Inflorescence: Arrangement of flowers on the floral axis (modified shoot apical meristem).
  • Floral Whorls: Calyx (Sepals), Corolla (Petals), Androecium (Stamens), and Gynoecium (Pistil).
  • Symmetry:
    • Actinomorphic: Radial symmetry (Mustard, Chilli).
    • Zygomorphic: Bilateral symmetry (Pea, Beans).
    • Asymmetric: Cannot be divided into equal halves (Canna).
  • Ovary Position:
    • Hypogynous: Superior ovary (Mustard, Brinjal).
    • Perigynous: Half inferior ovary (Plum, Rose, Peach).
    • Epigynous: Inferior ovary (Guava, Cucumber).

Reproductive Characteristics and Fruits

  • Aestivation: Mode of arrangement of sepals/petals in floral buds.
  • Androecium Variations: Epipetalous (attached to petals), Monadelphous (one bundle - China rose), Diadelphous (two bundles - Pea), and Staminode (sterile stamen).
  • Gynoecium: Syncarpous (fused ovaries) or Apocarpous (free ovaries).
  • Fruit Types:
    • Drupe: Developed from monocarpellary superior ovaries (Mango and Coconut).
    • Parthenocarpic: Developed without fertilisation (Banana).
  • Seed Structure: Monocots (e.g., Maize) feature an aleurone layer, Scutellum (cotyledon), Coleoptile (plumule sheath), and Coleorhiza (radicle sheath).

Solanaceae (Potato Family)

  • Vegetative: Herbs/shrubs, alternate leaves, reticulate venation.
  • Floral Features: Bisexual, actinomorphic, valvate aestivation, epipetalous stamens, bicarpellary syncarpous gynoecium with superior ovary.
  • Floral Formula: \oplus \text{ } \unicode{x26A5} \text{ } K_{(5)} \text{ } C_{(5)} \text{ } A_5 \text{ } \underline{G}_{(2)}