Different Agents Of The Seed Dispersal

Key Notes :

1. Wind (Anemochory)

  • How it works: Seeds are carried by the wind to different areas.
  • Characteristics of wind-dispersed seeds:
    • Light weight: Seeds are often small, light, or have wings or hairs that help them float in the air.
    • Examples: Dandelions, maple trees, and cottonwood trees.
    • Advantages: Can spread seeds over long distances, helping plants colonize new areas.

2. Water (Hydrochory)

  • How it works: Seeds are dispersed by water through rivers, lakes, or oceans.
  • Characteristics of water-dispersed seeds:
    • Buoyant: Seeds are often light and have a hard outer coating that prevents them from absorbing water.
    • Examples: Coconut, water lilies, and mangroves.
    • Advantages: Water dispersal can reach distant shores and islands.

3. Animals (Zoochory)

  • How it works: Seeds are dispersed by animals in different ways:
    • External Dispersal: Seeds attach to the fur or feathers of animals.
    • Internal Dispersal: Seeds are eaten by animals and later excreted in a different location.
  • Characteristics of animal-dispersed seeds:
    • Hooks and Barbs: Seeds have spines or hooks that cling to animal fur.
    • Fleshy Fruits: Some seeds are enclosed in juicy, sweet fruits that attract animals to eat them.
    • Examples:
      • External: Burdock (seeds cling to fur).
      • Internal: Berries eaten by birds (e.g., strawberries, tomatoes).
  • Advantages: Animals can carry seeds to new areas, even across barriers like mountains or rivers.

4. Gravity (Barochory)

  • How it works: Seeds fall from the plant to the ground due to gravity.
  • Characteristics of gravity-dispersed seeds:
    • Heavy or large: These seeds are often heavy or large and fall near the parent plant.
    • Examples: Acorns, apples, and chestnuts.
  • Advantages: Seeds are placed directly under the plant, ensuring good growth conditions if they fall on fertile soil.

5. Explosions (Autochory)

  • How it works: Some plants release seeds with a forceful mechanism, often causing the seeds to be ejected at a distance.
  • Characteristics of explosion-dispersed seeds:
    • Mechanism: The seed pods burst open when they dry out, launching seeds into the air.
    • Examples: Peas, witch hazel, and poppies.
  • Advantages: Explosive dispersal helps spread seeds rapidly in all directions.

6. Humans (Anthropochory)

  • How it works: Humans may move seeds intentionally or accidentally (e.g., through trade, transportation, or gardening).
  • Examples: Planting crops, transporting seeds in bags, or seeds being carried in footwear or clothing.
  • Advantages: Helps in the spread of cultivated plants and even invasive species.

Summary of Seed Dispersal Agents:

  • Wind: Disperses lightweight seeds.
  • Water: Carries buoyant seeds to new locations.
  • Animals: Includes external and internal dispersal through consumption or attachment.
  • Gravity: Seeds simply fall from the plant.
  • Explosions: Seeds are forcefully ejected by the plant.
  • Humans: Seeds spread through human activities.

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