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Flower

• The flower is the reproductive part of a flowering plant, commonly referred to as a bloom or blossom.
• A flower contains both female and male reproductive organs, contributing to sexual reproduction.

Structure of Flower

• Flowers consist of two main types of whorls:
  • Accessory whorls
  • Essential whorls

Accessory Whorls

• Calyx:
  • Made up of sepals.
• Corolla:
  • Made up of petals.

Essential Whorls

• Androecium:
  • This is the male part of the flower.
• Gynoecium:
  • This is the female part of the flower.

Parts of a Flower

• Sepal:
  • Protects the flower bud.
• Petal:
  • Often brightly colored to attract pollinators.
• Thalamus:
  • The swollen tip of the pedicel; varies in shape (flat, conical, dome-shaped).
• Stamen:
  • Composed of the anther and filament.
• Pedicel:
  • The flower stalk connecting the flower to the rest of the plant.

Thalamus

• The thalamus serves as the base of the flower and supports the reproductive organs.

Nectar

• Nectar is a sweet liquid produced by nectarites in the flower.
  • Its primary function is to attract insects for pollination.

Calyx

• The calyx is the outermost whorl of the flower and is made up of sepals.
  • Sepals are usually green, though they can sometimes be colored.

Functions of Calyx

• Protects the flower during the bud stage.
• Prevents the drying out of inner flower parts.
• Sometimes may remain on the plant to protect the fruit.

Types of Sepals

• Petaloid:
  • Sepals that resemble petals.
• Gamosepalous:
  • Sepals that are fused together.
• Caducous:
  • Sepals that fall off after flowering.
• Deciduous:
  • Sepals that fall off after fertilization.
• Polysepalous:
  • Sepals that are free (not fused).

Corolla

• The corolla is the second whorl of the flower and consists of petals.
  • Petals are typically brightly colored to attract pollinators.

Types of Corollas

• Based on Cohesion:
  • Polypetalous:
  • Petals are free or individual.
  • Gamopetalous:
  • Petals are fused together.
• Based on Shape:
  • Papilionaceous:
  • Butterfly-shaped petals.
  • Campanulate:
  • Bell-shaped petals.

Androecium

• The androecium is the third whorl of the flower and consists of stamens, which are the male reproductive organs.

Structure of Androecium

• Filament:
  • A thin stalk that supports the anther.
• Anther:
  • Knob-like structure at the top of the filament.
• Connective:
  • The tissue that joins the lobes of the anther at the top.

Anther Structure

• The anther is typically divided into two lobes, each containing pollen sacs.
• Pollen Grains:
  • Found inside the pollen sacs, these are the male gametes and are powdery and granular in texture.

Types of Stamens

• Monadelphous:
  • Stamens united to form a single group.
• Diadelphous:
  • Stamens united into two groups.
• Polyadelphous:
  • Stamens united into more than two groups.
• Sygenious:
  • Anther fused while the filaments remain free.

Inflorescence

• Inflorescence refers to the arrangement of flowers on a floral axis.

Placentation

• Placentation describes how the placentae are distributed within the cavity of the ovary in flowers.