Morphology of Flowering Plants - Notes | Class 11 | Part 6: Plant families

Morphology of Flowering Plants - The Leaf

Semi-Technical Description of a Typical Flowering Plant

  • The plant is described beginning with its habit, vegetative characters, and then floral characters.
  • Then a floral diagram and a floral formula are presented.
  • Floral formula is represented by some symbols.
  • Fusion is indicated by enclosing the figure within brackets and adhesion by a line drawn above the symbols of the floral parts.
  • Floral formula also shows cohesion and adhesion within parts of whorls and between whorls.
  • A floral diagram gives information about the number of parts of a flower, their arrangement and relation.
Floral diagram of mustard plant (Family: Brassicaceae)

Floral formula: ⊕⚥K₂₊₂ C₄ A₂₊₄ G(₂)


Some Important Families

1. Fabaceae

This family was formerly known as Papilionoideae, a subfamily of Leguminosae. It is distributed worldwide.

Vegetative Characters

  • Trees, shrubs, or herbs; roots with nodules.
  • Stem: Erect or climber.
  • Leaves: Alternate; pinnately compound or simple. Leaf base pulvinate; stipulate; venation reticulate.

Floral Characters

  • Inflorescence: Racemose.
  • Flower: Bisexual, zygomorphic.
  • Calyx: Sepals five, gamosepalous; valvate or imbricate aestivation.
  • Corolla: Petals five, polypetalous, papilionaceous (with a posterior standard, two lateral wings, and two anterior petals forming a keel that encloses the stamens and pistil); vexillary aestivation.
  • Androecium: Ten, diadelphous, anthers dithecous.
  • Gynoecium: Ovary superior, monocarpellary, unilocular with many ovules, style single.
  • Fruit: Legume; seed one to many, non-endospermic.

Floral Formula

%⚥K(₅) C₁₊₂₊(₂) A(₉)₊₁ G₁

Fabaceae Floral Diagram

Economic Importance

  • Pulses: e.g., gram, arhar, sem, moong, soybean.
  • Edible oil: e.g., soybean, groundnut.
  • Dye: e.g., Indigofera.
  • Fibres: e.g., sun hemp.
  • Fodder: e.g., Sesbania, Trifolium.
  • Ornamentals: e.g., lupin, sweet pea.
  • Medicine: e.g., muliathi.

2. Solanaceae (Potato Family)

It is a large family widely distributed in the tropics, subtropics, and even temperate zones.

Vegetative Characters

  • Habit: Mostly herbs, shrubs, and small trees.
  • Stem: Herbaceous, rarely woody. Aerial; erect, cylindrical, branched, solid or hollow; hairy or glabrous. Underground stem in potato (Solanum tuberosum).
  • Leaves: Alternate, simple, rarely pinnately compound, exstipulate; venation reticulate.

Floral Characters

  • Inflorescence: Solitary, axillary or cymose (as in Solanum).
  • Flower: Bisexual, actinomorphic.
  • Calyx: Sepals five, united, persistent, valvate aestivation.
  • Corolla: Petals five, united; valvate aestivation.
  • Androecium: Stamens five, epipetalous.
  • Gynoecium: Bicarpellary, obliquely placed, syncarpous; ovary superior, bilocular, placenta swollen with many ovules, axile.
  • Fruits: Berry or capsule.
  • Seeds: Many, endospermous.

Floral Formula

⊕⚥K(₅) C(₅) A₅ G(₂)

Solanaceae Floral Diagram

Economic Importance

  • Food: e.g., tomato, brinjal, potato.
  • Spice: e.g., chilli.
  • Medicine: e.g., belladonna, ashwagandha.
  • Fumigatory: e.g., tobacco.
  • Ornamentals: e.g., petunia.

3. Liliaceae (Lily Family)

A characteristic representative of monocotyledonous plants. It is distributed worldwide.

Vegetative Characters

  • Perennial herbs with underground bulbs/corms/rhizomes.
  • Leaves: Mostly basal, alternate, linear, exstipulate with parallel venation.

Floral Characters

  • Inflorescence: Solitary/cymose; often umbellate clusters.
  • Flower: Bisexual; actinomorphic.
  • Perianth: Tepal six (3+3), often united into tube; valvate aestivation.
  • Androecium: Stamen six, (3+3).
  • Gynoecium: Tricarpellary, syncarpous, ovary superior, trilocular with many ovules; axile placentation.
  • Fruit: Capsule, rarely berry.
  • Seed: Endospermous.

Floral Formula

⊕⚥P(₃₊₃) A₃₊₃ G(₃)

Liliaceae Floral Diagram

Economic Importance

  • Ornamentals: e.g., tulip, Gloriosa.
  • Medicine: e.g., Aloe.
  • Vegetables: e.g., Asparagus.
  • Colchicines: e.g., Colchicum autumnale.

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