One of a plant’s main goals is to reproduce. For many flowers, shrubs, and trees, that method is primarily done by seed.
There are many ways in which seeds can be dispersed: by air, water, fire, gravity, by explosion, and by animals. Read on to learn more:
Two of the most common seed dispersal technique by air we see is through the “helicopters” of maple trees and the feather heads of dandelions. When they get blown off the tree/plant, the elongated wings catch the air and allow them to float for extended distances. This enables the tree to disperse its seeds far and wide so that its offspring won’t be competing for space in the tree’s immediate dripline.
Other seeds dispersed by air often have elongated and flattened features like wings or blades to allow the wind to carry them long distances.
Plants growing near bodies of water have another method of transportation available to them – the water. If the plant were to produce buoyant seeds, they can use the currents to travel to new and suitable environments. In the tropics, buoyant coconut and mangrove seeds have proven to be very successful, thus being responsible for the many coconut trees seen on many beaches in the tropics.
Another example of seed dispersal by water is through sea beans.
The use of gravity is a simple seed dispersal technique. As fruit/seeds get heavier, they are pulled down by gravity, causing them to fall when ripe. If the seed/fruit is round like an apple, it can roll away to farther distances
There are some seeds that can literally explode, catapulting and flinging seeds into the air. This can be achieved by the build up of pressure and seeds dry out. When disturbed, the pressure is released, sending the seeds out in many directions. Some examples of seeds that explode include Himalayan Balsam, squirting cucumber, witch hazel, and geraniums
Seed dispersal by animal can be a topic unto itself as there are many methods for this to occur. The first by via the outside of animals whether by adhesive mucus, hooks, spines, and barbs. Think of seeds like burrs that stick to your clothes as you hike through the forest.
Seeds can also be dispersed by ingestion (and subsequent excretion) by birds and mammals. After an animal eats a fruit, with the seeds tucked inside, it passes through the digestive tract and emerges out the other end often as the animal has moved to a new location.
Seeds can also be dispersed by ants, as well as by squirrels that hoard and hide a variety of seeds, but don’t come back to retrieve them before the germinate.