Plants disperse their seeds so that they can reproduce. Seed dispersal is critical to the future of each plant species. Plants use different strategies to disperse their seeds. These strategies vary according to the plant. Plants in different environments disperse their seeds in different ways, using the wind, water or animals to move their seeds to new places.
Most of us have seen seeds floating on the wind. Those who live in areas with cottonwood trees see seeds floating in the air like snow in spring. Maple trees are popular with young children who love to throw the tree's seeds into the air and watch them spiral to the ground like helicopters. The air moves these helicopter-like seeds around and they land in other parts of the forest. Dandelions are well-known for their ability to disperse their seeds on the wind, much to the dismay of gardeners. Seeds that disperse using the wind can be large or small. Smaller airborne seeds tend to be airy like the dandelion seed, while larger ones are aerodynamically-shaped like the maple seed.
Some plants in wet environments move their seeds using water. Coniferous trees may drop their cones into water, and the water carries the seeds far away. The coconut tree is famous for its ability to disperse its large seeds in water bodies, where they will float. For plants with larger seeds that cannot be carried on the wind, water bodies help move big seeds around.
Animals and birds
Plants use animals to disperse seeds. Seeds are often tasty and full nutrients for animals, so animals eat them. Parts of the seed may pass through the animal. When the animal defecates, the seeds end up in the soil. Seeds in the form of burrs attach themselves to animals for free rides. These seeds move through the forest on the animal's fur until the animal rubs them off. Birds are particularly good at moving seeds to new places, since they can fly to places that terrestrial animals might not be able to go. Many invasive plants like holly move successfully from place to place via birds that eat their berries.
Some seeds have a rather noticeable way of dispersing their seeds. Touch-me-nots open explosively and release their seeds, often when it is very windy or when an animal touches them. This is a good way for the plant to give the seeds a head start and make it easier for them to move on the wind or onto an animal's fur.