Biology of Flowers: Pollination and Parts

Study Notes

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

A flower has four main parts: sepal, petal, stamen, and pistil.
Each part plays a significant role in protecting, attracting pollinators, and reproducing.
Sepal: protects the other parts of the flower.
Petal: provides a unique appearance, shape, color, and scent to attract pollinators.
Stamen: the flower's male reproductive part, consisting of an anther and a filament.
Pistil: the flower's female reproductive part, composed of the ovary, stigma, and style.

Pollen is transferred from one flower to another through different vectors, including wind, water, birds, insects, butterflies, bats, and other animals.
Animals and insects capable of carrying and dispersing pollen grains are collectively called pollinators.

Essential for fertilization and production of enough seeds for dispersal and propagation.
Maintains genetic diversity within a population and develops an adequate number of fruits.
Crucial for ecosystem survival, as most crops and food and plant-based products depend on successful pollination.
Increases crop and fruit yields and has environmental benefits, such as producing oxygen and purifying water.

Two methods of pollination: abiotic (wind and water) and biotic (insects and other animals).
Abiotic pollination: does not require other organisms, used by 20% of plants (e.g., conifers, grasses, cereal crops).
Biotic pollination: requires the help of insects and other animals, used by 80% of plants (e.g., flowers with colors, shapes, and scents).

Most wind-pollinated flowers appear in spring before or while the leaves are only starting to emerge.
Flowers are typically small, without petals, odor, or nectar, with large and feathery stigmas.

Plants develop strategies to attract pollinators and effectively disperse their pollen.
Methods include visual cues, scent, food, mimicry, and entrapment.

Self-pollination: occurs when the plant fertilizes itself, resulting in genetically identical offspring.
Cross-pollination: requires a pollinator or vector to transfer pollen from one flower to another of the same species.

Between 200,000 to 300,000 invertebrate species are considered pollinators globally.
Around 2000 vertebrates (e.g., birds, mammals, and reptiles) also help pollinate plants and crops.
Bees are the primary plant pollinators.
At least 1500 crop plant species depend on pollinators for reproduction.
About 30% of the human diet, fibers, edible oils, and medicine come from plants and other plant-derived products, which are only possible due to pollinators and pollination.