Birds and Bees – Seed Dispersal

Seeds dispersal refers to the transport of seeds from their plants of origin to new locations, where they can germinate and grow (or lie dormant until the right conditions exist). The seed shape and its characteristics help determine this locomotion, typically by wind, animals, water, bursting, or by humans.

Seed dispersal mechanisms - (C) Encyclopaedia Britannica (2006)

• Some seeds are equipped with parachutes, sails, wings, and propellers, and are carried on the wind. You might have blown on a dandelion to disperse its tiny parachutes, or seen a cottonwood tree release its seed fluffs.
• Animals play a part as well, by burying seeds, transporting burrs on their fur, or ingesting seeds, which pass through their digestive systems. (If you have been instructed to scarify a seed before planting, chances are in the wild the seed type must pass through an animal’s digestive system before it can germinate).
• Riparian plants may rely on water for pollination. Some seeds, like the coconut, are light enough to float to a favorable location.
• Some seeds burst out of their pod or container when the conditions are right (some actually need fire to be released).
• Humans also play their part, through planting crops, or transporting seeds from the nursery to their gardens.

I typically do not deadhead, because I love to see my plants go through their entire reproductive cycle, including producing seeds. I had once planned to remove a messy, and awkwardly placed black cherry tree in the back yard, until I witnessed a group of little brown birds devour its tiny cherries in an afternoon. How could I remove this food source, and dispersal system from our tiny ecosystem?

Learn More:

• Botany for Gardeners, by Brian Capon (Timber Press 2005). See Part V Reproduction, Chapter 9, “From Flowers to Fruits”.
• Pollination and Fertilization, derived from Pollination and Fertilization, by Robert Bear and David Rintoul, for Open Stax, Rice University (Creative Commons).