Wind
Some plants depend on the wind to spread their seeds. In these cases, the seeds are often attached to fine, fluffy threads that catch the breeze, enabling them to float to a new patch of land. Examples of plants with these seed adaptation are dandelions and cattails. Some tree seeds, such as those from maples and ashes, also depend on the wind. These seeds will often have a propeller shape.
Water
Plants also use water to transport their seeds to new locations. Coconuts -- which are a seed -- are an example. The thick shells keep the salt water out and the buoyant coconuts can float on the sea for hundreds of miles without being damaged.
Animals
Animals are another way seeds are dispersed. Plants that use this method have seeds that attract animals, such as berries. After the seeds have passed through an animal's digestive tract, they can take root at the site of the animal dropping containing the seed. Other seeds are adapted to stick to animal fur. Such seeds, often known to humans as burrs, eventually fall off and take root.
Germination
Some seeds have extra adaptations that help control when the seeds are germinated no matter how the seeds were dispersed. For example, some seeds will not germinate -- or begin to grow -- until after a fire. Those seeds depend on the heat to crack the shell or open the pine cone, allowing the seeds to drop to the ground. Other seeds depend on the wind to scratch their casings, allowing water to seep into the seed and begin the germination process.