Plant Reproduction
1. Sexual Reproduction
Sexual reproduction in plants involves the fusion of male and female gametes. This process takes place in the flowers, where pollen grains (male gametes) fertilize ovules (female gametes). Flowers are designed to attract pollinators such as bees, butterflies, and birds, ensuring the successful transfer of pollen.
2. Process After Fertilization
After fertilization, the fertilized ovule develops into a seed. The surrounding ovary begins to transform into a fruit that will protect and aid in the dispersal of the seeds. During this time, the zygote undergoes several divisions to form the embryo, while the ovule’s tissue develops into the seed coat.
3. Structure of a Seed
A seed comprises three main parts:
- Embryo: The young plant that will develop into a mature plant.
- Stored Food: Nutrients that provide energy to the embryo during germination.
- Seed Coat: A protective outer layer that shields the seed from damage and dehydration.
4. Seed Germination
Seed germination is the process by which a seed develops into a new plant. Optimal conditions such as moisture, warmth, and oxygen are necessary for germination. Initially, the seed absorbs water, swells, and eventually cracks open, allowing the embryo to emerge as a seedling.
5. Dispersal of Seeds
Seeds need to disperse from the parent plant to reduce competition and foster growth in new environments. There are several modes of seed dispersal:
- (a) Need of Seed Dispersal: Helps prevent overcrowding and allows plants to colonize new habitats.
- (b) Agents of Dispersal: Various agents such as wind, water, and animals assist in spreading seeds.
- (c) Water: Some seeds can float on water and are carried to new locations.
- (d) Animals: Animals eat fruits and excrete the seeds elsewhere, aiding in dispersal.
- (e) Self-Explosion: Certain plants have mechanisms that allow seeds to be forcibly ejected from the parent plant.
6. Vegetative Reproduction in Plants
Vegetative reproduction is a form of asexual reproduction where new plants grow from parts of the parent plant. This can happen through tubers, rhizomes, or cuttings. It offers a quick and efficient way for plants to reproduce and colonize an area.