Plant Reproduction

Plant Reproduction and Development

• Key Terms:

  • Seedling

  • Stigma

  • Style

  • Embryo

  • Nucleus

  • Endosperm

  • Zygote

Review of Plant Characteristics

• Multicellular organisms: Plants consist of multiple cells.

• Photosynthetic capacity: Ability to synthesize food using sunlight.

• Cellulosic cell wall: Provides structure and protection.

• Plastids: Organelles in the cytoplasm involved in photosynthesis and storing starches.

• Life cycle with alternation of generations: Alternates between a haploid gametophyte and diploid sporophyte phase.

Forms of Reproduction in Angiosperms

Asexual Reproduction

• Requires a single parent.

• Does not involve fusion of gametes.

• Offspring are genetically identical to the parent (clones).

Sexual Reproduction

• Involves two parents.

• Includes self-pollination or cross-pollination.

• Requires fusion of sperm cell and egg cell during fertilization.

• Offspring are genetically diverse.

Review of Major Plant Groups

Land Plants

• Classified into two main categories:

  • Non-Vascular Plants:

    • Hornworts

    • Liverworts

    • Mosses

  • Vascular Plants:

    • Pteridophytes (ferns, horsetails, lycophytes)

    • Spermatophytes (seed-bearing)

      • Gymnosperms (cone-bearing)

      • Angiosperms (flowering)

Asexual Reproduction Methods

Vegetative Methods

• Runners:

  • Horizontal stems that grow along the ground, forming new plants (e.g., strawberries).

• Rhizomes:

  • Underground stems that grow horizontally (e.g., ginger).

• Tubers:

  • Swollen underground stems that store nutrients (e.g., potatoes).

• Bulbs:

  • Storage organs with fleshy leaves (e.g., onions).

Artificial Methods

• Cutting:

  • A part of stem, root, or leaf is cut and planted (e.g., roses).

• Layering:

  • A stem is bent, covered with soil, and roots develop (e.g., jasmine).

• Grafting:

  • Attaching a stem or bud from one plant to another (e.g., apples).

• Micropropagation:

  • Growing small plant tissues in nutrient-rich medium (e.g., orchids).

Floral Anatomy

• Pistil:

  • Female structure; includes stigma, style, and ovary.

• Stamen:

  • Male structure; comprises anther and filament.

• Ovary:

  • Houses female gametes (ovules).

• Anther:

  • Produces and stores pollen grains.

• Filament:

  • Supports the anther.

• Petals:

  • Colorful parts attracting pollinators.

• Sepals:

  • Protects flower buds.

• Receptacle:

  • Thickened portion below ovary; where floral parts grow.

• Pedicel:

  • Stalk of the flower supporting floral parts.

Angiosperm Life Cycle

1. Seeds inside fruit contain developing embryos.

2. Initial sporophyte stage as seeds develop.

3. Embryos differentiate into seedlings.

4. Continuous growth leads to maturity.

5. Adults produce gametophytes via pollens and ovules.

6. Fusion of gametes occurs during pollination.

7. Ovary develops into fruit; ovules become seeds.

Gymnosperm Life Cycle

• Differences between Angiosperms and Gymnosperms:

  • Male and female gametophytes produced in cones.

  • Pollination occurs with fertilization, turning ovules into seeds.

Fern Life Cycle

• Spores at underside of fronds develop into gametophytes.

• Gametophytes produce eggs and pollen.

• Fertilization forms zygote, developing into sporophyte.

Comparison of Reproductive Structures and Processes

• Angiosperms:

  • Floral structures present; seeds and fruits formed.

• Gymnosperms:

  • Cones present; seeds produced but no flowers or fruits.

• Pteridophytes/Bryophytes:

  • No floral structures; rely on spores for reproduction.