Introduction to Plant Reproduction

Study Notes

Involves the fusion of male and female gametes (sex cells).
This method often leads to greater genetic diversity in offspring.
Two main processes involved in sexual reproduction:
- Pollination: Transfer of pollen (male gametes) from the stamen to the pistil (female part) of a flower. Can be done by wind, insects, birds, or other animals.
- Fertilization: Fusion of the male and female gametes (sperm and egg) within the ovary to form a zygote.
Flowers: The primary reproductive structures in flowering plants (angiosperms).
Parts of a flower: Stamen (male part) with anther and filament; pistil (female part) with stigma, style, and ovary. Ovules inside the ovary develop into seeds.

Does not involve the fusion of gametes.
Results in offspring genetically identical to the parent plant.
Common methods include:
- Vegetative propagation: Producing new plants from parts of the parent plant, like stems, roots, or leaves.
  - Runners: Horizontal stems that grow along the ground, creating new plants at nodes.
  - Tubers: Swollen underground stems, like potatoes, that contain buds for new plant growth.
  - Bulbs: Underground stems surrounded by fleshy leaves, like onions, that produce new plants.
  - Cuttings: A piece of stem or leaf that grows into a new plant when planted in the right conditions.
  - Grafting: Joining a piece of one plant to another plant to create a new individual.
- Spore formation: Some plants reproduce through spores, small reproductive cells that grow into new plants under suitable conditions.
Advantages of asexual reproduction: Rapid increase in number of plants, producing genetically identical offspring suited to the environment.
Disadvantages: Lower genetic diversity, making the species vulnerable to disease or changes in the environment.

Wind pollination: Pollen is carried by wind currents to the pistil of another flower.
Insect pollination: Pollen is transferred by insects (e.g., bees, butterflies, moths) that are attracted to the flower's color, shape, and scent.
Other pollinators: Birds, bats, and other animals can also transfer pollen.

Seeds need to be dispersed away from the parent plant to compete for resources.
Methods of seed dispersal include:
- Wind dispersal: Seeds with light structures can be carried by wind.
- Animal dispersal: Seeds with hooks or fleshy coatings are eaten by animals, and the seeds pass through the digestive system and are deposited elsewhere.
- Water dispersal: Some seeds have structures that allow them to float on water and travel to new locations.

Essential for the survival of plant species and maintaining biodiversity.
Provides food and resources for humans and other organisms, including raw materials for various industries.