Learning Objectives
- Understand modes of reproduction in plants
- Learn about asexual reproduction methods
- Understand sexual reproduction in flowering plants
- Know about seed dispersal and its methods
Key Concepts
Modes of Reproduction
Asexual reproduction: New plant from a single parent without seeds. Faster and produces identical offspring (clones).
Sexual reproduction: Involves fusion of male and female gametes. Produces seeds. Results in variation.
Asexual Reproduction Methods
- Vegetative propagation: New plant from vegetative parts (stem, root, leaf). Examples: potato (tuber), ginger (rhizome), Bryophyllum (leaf), rose (stem cutting).
- Budding: A bud grows on parent and detaches as new organism. Example: Yeast, Hydra.
- Fragmentation: Parent body breaks into fragments, each growing into new organism. Example: Algae (Spirogyra).
- Spore formation: Spores are tiny cells with thick walls that grow into new plants in favourable conditions. Example: Ferns, mosses, bread mould.
Sexual Reproduction in Flowering Plants
Flower parts: Sepals, Petals, Stamens (male), Pistil (female).
Stamen: Male part consisting of anther (produces pollen) and filament.
Pistil: Female part consisting of stigma, style, and ovary (contains ovules).
Pollination: Transfer of pollen from anther to stigma. Self-pollination (same flower) or Cross-pollination (different flower, by insects, wind, water).
Fertilisation: Fusion of male gamete (in pollen) with female gamete (in ovule). After fertilisation, ovule becomes seed, ovary becomes fruit.
Seed Dispersal
Seeds are dispersed to avoid overcrowding. Methods:
- By wind: Light seeds with wings/hair (maple, dandelion)
- By water: Seeds that float (coconut)
- By animals: Sticky/hooked seeds (Xanthium), fleshy fruits eaten by animals
- By explosion: Pods burst and scatter seeds (pea, balsam)
Summary
Plants reproduce asexually (vegetative propagation, budding, fragmentation, spores) or sexually (pollination → fertilisation → seed formation). Flowers have male (stamen) and female (pistil) parts. Seeds are dispersed by wind, water, animals, and explosion.
Important Terms
- Pollination: Transfer of pollen to stigma
- Fertilisation: Fusion of male and female gametes
- Stamen: Male reproductive part (anther + filament)
- Pistil: Female reproductive part (stigma + style + ovary)
- Seed dispersal: Spreading of seeds away from parent
Quick Revision
- Asexual: vegetative propagation, budding, fragmentation, spores
- Flower = Sepals + Petals + Stamen (male) + Pistil (female)
- Pollination → Fertilisation → Seed + Fruit
- Ovule → Seed, Ovary → Fruit
- Dispersal by: wind, water, animals, explosion