Seeds must be dispersed by plants so that offspring are not forced to compete with parent plants for resources. For gardeners and homeowners, it is important to disperse some seeds, such as grass seeds, uniformly to ensure that the resulting lawn looks even and contains no bare patches. A number of forces disperse seeds, including wind, water, animals and seed-spreading tools.
If a parent plant, which may produce tens of thousands of seeds each year, simply dropped its seeds directly below it, the resulting seedlings would have very little chance for survival. In addition to blocking most of the sunlight, parent plants have extensive and established root systems that would work to prevent the seedlings from obtaining enough water and nutrients from the soil. If too many of the seedlings establish themselves directly under the parent plant, the parent may also suffer from being unable to obtain enough water.
When homeowners or gardeners plant seeds, they must be careful to do so evenly. Not only does this prevent bare patches from developing, but even distribution also maximizes the efficiency of the process. If seeds are distributed in dense clumps, some of the seeds are sure to die and represent wasted resources.