Biology of Flower Structure and Pollination

Parts of a Flower

• A complete flower contains both male and female reproductive organs, but some flowers may only have one of the two.
• The four main parts of a flower are sepal, petal, stamen, and pistil.

Sepal

• The sepal protects the other parts of the flower and looks like tough green leaves surrounding the bud.

Petal

• The petals provide a unique appearance to the flower, attracting pollinators such as insects and hummingbirds with shape, color, and scent.

Stamen

• The stamen is the male reproductive part of the flower, consisting of an anther and a filament.
• The anther produces and disperses pollen grains containing male reproductive cells.
• The filament is the stalk supporting the anther.

Pistil

• The pistil is the female reproductive part of the flower, composed of the ovary, stigma, and style.
• The ovary contains the female reproductive cells and is found at the base of the pistil.
• The stigma is the sticky region at the top of the pistil that catches pollen grains.
• The style is the stalk of the pistil, found between the ovary and the stigma.

Pollination

• Pollination is the transfer of pollen grains from a flower's male anther to the female stigma.
• Pollination's primary purpose is to produce seeds and offspring for the next generation.

Methods of Pollination

• There are two methods of pollination: abiotic (wind and water) and biotic (insects and other animals).
• About 80% of plant pollination occurs with the support of animals, while the remaining 20% is through wind and water.

Wind Pollination

• Wind-pollinated flowers appear in spring, before or while the leaves are emerging.
• Characteristics of wind-pollinated flowers include lightweight, smooth, and small pollen, and large, feathery stigmas.
• Examples of wind-pollinated plants include conifers, grasses, cereal crops, ragweed, and cat-tail.

Animal Pollination

• Plants that rely on animals for pollination develop strategies to attract pollinators, such as visual cues, scent, food, mimicry, and entrapment.
• Plants produce sticky and barbed pollen for easier attachment and transfer to other flowers.
• Flowers display their petals, shape, color, and nectar guides to attract pollinators.

Types of Pollination

• There are two types of pollination: self-pollination and cross-pollination.
• Self-pollination occurs when the plant fertilizes itself, resulting in genetically identical offspring.
• Cross-pollination occurs when pollen is transferred from one flower to another of the same species, providing the offspring with desirable characteristics from both parents.

Importance of Pollination

• Pollination is essential for fertilization and production of seeds for dispersal and propagation.
• It is crucial for maintaining genetic diversity within a population and developing an adequate number of fruits.
• The ecosystem would not survive without pollination, and most crops and food products depend on successful pollination.
• Pollination also has environmental benefits, such as producing oxygen and purifying water.