How are seeds dispersed?
Awareness of seed dispersal mechanisms is the best way to prevent the spread or introduction of new invasive species.
By David Tork, University Of Minnesota
Sustainable Secure Food Blog
February 7, 2022
Excerpt:
Seed dispersal in plants takes on countless forms, yet most dispersal mechanisms fall within the categories of gravity, wind, water, and animal dispersal. Let’s dive into these mechanisms in more detail. Next time you’re out walking, see if you can spot them in action.
Wind
The common dandelion is perhaps the most iconic, and well-known species to use wind dispersal. The windsail-like structure, called the pappus, opens and closes in response to moisture. On dry, windy days the pappus opens, catches the wind, and transports lightweight dandelion seeds far away from the parent plant.
Other plants use winged structures (like the propellor-shaped maple samara) or wooly structures (like fuzzy cottonwood seeds) to facilitate wind-dispersal.
Gravity
Gravity dispersal, also known as “shattering” or “fruit drop” is the dispersal of a seed by falling. As the fruit reaches maturity, a natural process called abscission weakens supporting structures like stems and seed pods. This is what causes a ripe apple to fall from the tree. Abscission also causes fruit-containing structures to open and drop their seed on the ground.
