Lecture on Plant Reproduction and Anatomy

Introduction

• Ganglion-like Structure: Capillary structure unique to diatomaceous mitosis, different from other organisms.
• Sporophyte and Gametophyte: Main distinction among plant types is size.

Seed Plants

• Considered more primitive but still evolving.
• Gymnosperms
  • Male and female parts usually on the same tree (monoecious).
  • Structures: Strobilus (cone-like structures), Megastrobilus (female), Microstrobilus (male).
  • Ovules function as megasporangia.
  • Megasporocyte undergoes meiosis, resulting in a megaspore that develops into a female gametophyte.
  • Fertilization typically results in one seed per ovule.

Angiosperms

• Flower Structure: Male and female parts are often enclosed in flowers, providing additional protection.
• Features of Flowers
  • Modified leaves, including carpels and stamens.
  • Double fertilization: Leads to triploid endosperm tissue.
• Fruit Formation
  • Ovules develop into seeds; ovaries develop into fruits.
  • Significant reduction in female gametophyte size compared to gymnosperms.

Differences Between Gymnosperms and Angiosperms

• Gymnosperms: Exposed ovules, single integument.
• Angiosperms: Enclosed ovules, two integuments, stigma present.

Flower Types

• Perfect Flowers: Hermaphroditic, have both male and female parts.
• Imperfect Flowers: Separate male and female flowers.
  • Monoecious: Both male and female flowers on the same plant.
  • Dioecious: Male and female flowers on separate plants.

Pollination

• Gymnosperms rely on wind for pollination.
• Angiosperms often use animals, leading to more efficient pollination.

Fruit Types

• Dry Fruits: Includes nuts, achenes, legumes, capsules.
• Fleshy Fruits: Berries, drupes, pomes.
  • Aggregate Fruits: Develop from multiple ovaries of one flower (e.g., strawberries).
  • Multiple Fruits: Develop from multiple flowers (e.g., pineapples, figs).

Plant Anatomy

• Root System: Anchors plant, absorbs nutrients.
• Shoot System: Includes stems and leaves.
  • Stems: Support leaves, may branch.
  • Leaves: Primary site of photosynthesis.
• Leaf Structure: Consists of a blade and petiole.

Summary

• Evolution of plants from simple to complex structures.
• Adaptations in reproductive structures for efficiency and protection.
• Importance of pollination strategies in plant reproduction.