Campbel12.Chapter301

Adaptations of Seed Plants

• Seed plants make up a vast majority of plant biodiversity due to several adaptations:

  • Reduced gametophytes:

    • Gametophytes develop in cones (gymnosperms) or flowers (angiosperms).

  • Heterospory:

    • Production of two types of spores (male and female).

  • Ovules and pollen:

    • Pollen allows for fertilization without water, as it can be dispersed by wind or animals.

• Seed structure includes:

  • Embryo

  • Seed coat (protects the embryo)

  • Food supply (nourishes the embryo)

Life Cycle of Seed Plants

• Sporophyte-dominated life cycles:

  • Gametophytes are microscopic and dependent on the sporophyte for nutrition.

  • Sporophyte is the dominant structure (2n).

Key Features of Seed Plants

• Gametophyte Dependency:

  • Reduced gametophytes provide protection and nutrients from the parent plant.

• Adaptation to Land:

  • Water is not required for fertilization, advantageous for survival in diverse habitats.

Overview of Gymnosperms and Angiosperms

• Gymnosperms:

  • Bear protected "naked seeds" on cones.

  • Most common group: Conifers (pines, firs).

• Angiosperms:

  • Reproductive structures include flowers and fruits, making them the most diverse group of plants.

Flower Structure and Function

• Flowers consist of various organs:

  • Stamens (male reproductive) produce pollen.

  • Carpels (female reproductive) house ovules.

• Pollination can occur through animals or wind.

Fruit Development

• Fruits develop from the ovary and aid in seed dispersal.

• Types of fruits include fleshy (e.g., tomatoes) and dry (e.g., nuts).

Seed Dispersal Mechanisms

• Various adaptations ensure effective dispersal:

  • Parachute-like structures for wind dispersal.

  • Buoyant structures for water dispersal.

  • Burrs that cling to animals.

Importance of Seed Plants

• Seed plants are critical for human welfare:

  • Major food sources, including crops like wheat and rice.

  • Provide raw materials like wood and medicines.

• Preservation of plant diversity is essential due to habitat destruction and extinction risks.