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Asexual Reproduction in Fungi and Plants

• Budding

  • Yeasts reproduce by forming small, bud-like projections.

  • Buds gradually grow and detach from the parent, forming new yeast cells.

• Spore Formation

  • Fungi such as bread moulds propagate by producing spores.

  • Spores are tiny, spherical, unicellular bodies with protective walls.

  • They can withstand unfavourable conditions and germinate into new individuals when conditions improve.

• Fragmentation

  • Mosses, a type of non-flowering plant, grow on damp surfaces and produce green mat-like patches.

  • They form spores in cup-like structures that germinate into new moss plants.

• Reproduction in Non-flowering Plants

  • Ferns: Large non-flowering plants that produce spores on their leaves.

  • Pine Trees: Form cones that contain seeds; seeds germinate and give rise to new plants.

Experiential Learning on Spores

• Microscope Observation

  • Place water on a slide and leave it undisturbed for two days to observe fibrous structures called hyphae.

• Vegetative Propagation

  • Plants can propagate from roots, stems, or leaves.

  • Ruberous Roots: Store sugars and give rise to new plants in the next sowing season.

  • Rhizomes: Underground stems, like ginger and banana, develop buds and can propagate new plants.

Plant Propagation Techniques

• Rhizome Cutting

  • Rhizomes can be cut into sections, each containing a bud, for planting.

• Modified Stems

  • Potatoes are modified stems that can grow into new plants from pieces planted in soil.

• Budding in Cacti

  • Cacti develop buds that grow roots and can become separate plants.

• Bulbs

  • Underground stems with thick leaves propagate onions, garlic, and tulips.

• Runners

  • Long, thin stems that grow horizontally (e.g., strawberries) produce new plants wherever they touch the soil.

Vegetative Propagation Through Leaves

• Bryophyllum

  • Produces buds on leaf margins that detach and grow into new plants.

• Brahma Kamal

  • Can propagate by planting a piece of its leaf in moist soil.

Artificial Methods of Vegetative Propagation

• Cutting

  • Plants like roses can be propagated through stem cuttings that develop roots.

• Grafting

  • Joining a fast-growing or disease-resistant base plant (stock) with a stem cutting (scion) from another variety.

• Layering

  • Bending lower branches of plants (e.g., jasmine, grapevine) and covering them with soil to induce root growth.

• Tissue Culture

  • Specialized method growing a mass of cells from plant tissue in specific conditions to form new plants.

Sexual Reproduction in Plants

• Structure of Flowers

  • Most plants with flowers are known as flowering plants. They contain male (stamens) and female (pistils) reproductive parts.

  • Components: Sepals (protect flower parts), petals (attract pollinators), and reproductive structures.

  • A typical flower has four parts: sepals, petals, stamens, and a carpel (pistil).

• Pollination

  • Transfer of pollen grains from the anther to the stigma can occur via self-pollination (same plant) or cross-pollination (different plants).

  • Different pollinators (birds, insects, wind) facilitate this process, which is crucial for fertilisation.

Fertilisation and Seed Development

• Steps to Fertilisation

  • Pollen tube grows down the style to the ovary, where male gametes fertilise the female gametes in the ovule, creating a zygote.

  • The ovule develops into a seed, which eventually becomes a fruit.

Seed Germination and Dispersal

• Germination

  • Conditions must be favourable for seeds to germinate, with the embryo developing into a new plant.

• Dispersal Methods

  • By Water: Seeds like coconuts have fibrous coverings to allow floating.

  • By Wind: Light seeds with hair structures travel far.

  • By Exploding Pods: Some plants, like balsams, explode to release seeds.

  • Animal Ingestion: Animals transporting seeds via consumption and excretion.

Importance of Plant Propagation

• Understanding both asexual and sexual reproduction in plants aids in agricultural practices and maintaining plant biodiversity.