The flower is the reproductive unit in angiosperms. It typically consists of four whorls arranged on a fleshy base called the thalamus or receptacle.

• Calyx (Sepals): The outermost whorl, usually green; protects the flower in the bud stage and performs photosynthesis.
• Corolla (Petals): Often brightly colored to attract pollinators like insects and birds.
• Androecium (Stamens): The male reproductive part; produces pollen grains.
• Gynoecium (Carpels/Pistils): The female reproductive part; contains ovules that develop into seeds.

Morphologically, a flower is considered a modified determinate shoot. This concept is supported by several anatomical and developmental evidences:

• The thalamus represents a condensed axis with highly reduced internodes.
• Floral organs (sepals, petals, etc.) are homologous to leaves but modified for reproduction.
• Occasionally, the thalamus may continue to grow, showing a "proliferous" habit, which proves its shoot-like nature.

These are symbolic and graphical representations used to describe the characteristics of a flower.

Floral Formula: A shorthand notation representing the symmetry, sex, and number of floral parts.
Floral Diagram: A cross-sectional ground plan showing the arrangement and cohesion/adhesion of floral parts.

The evolution of reproductive organs marks a transition from leaf-like structures to highly specialized filaments and ovaries.

A. Stamen Evolution

• Primitive: Broad, leaf-like structures with embedded microsporangia (e.g., Degeneria).
• Advanced: Differentiation into a slender filament, a distal anther, and a connective.

B. Carpel Evolution

• Primitive: Open, leaf-like structures (megasporophylls) that folded to protect ovules (Conduplicate carpels).
• Advanced: Complete closure forming a distinct ovary, style, and stigma.

Placentation is the arrangement of ovules within the ovary.

Fruits develop from the mature ovary, while seeds develop from fertilized ovules.

Evolutionary Trends:

• Evolution from simple follicles to complex fleshy fruits to aid animal-mediated dispersal.
• Development of wings or hairs for wind dispersal.

Types of Fruits:

• Simple: Develop from a single ovary (e.g., Mango, Pea).
• Aggregate: Develop from a multicarpellary, apocarpous gynoecium (e.g., Raspberry).
• Multiple: Develop from an entire inflorescence (e.g., Pineapple, Jackfruit).

Germination is the process where the embryo within the seed grows into a seedling.

• Epigeal Germination: The hypocotyl elongates, pushing the cotyledons above the soil (e.g., Bean, Castor).
• Hypogeal Germination: The epicotyl elongates, and cotyledons remain underground (e.g., Pea, Maize).
• Viviparous Germination: Seeds germinate while still attached to the parent plant (common in Mangroves).