Since plants are non-motile, if a seed grows beneath a parent plant, it may be deprived of water, soil nutrients and solar energy due to the root system of the parent plant as well as its greater height. Competition between offspring and parent would not be a beneficial arrangement for the new embryo plant nor its parent. Mechanisms for seed dispersal arose to insure that the seeds, which are actually embryos with a food supply, get to a new location that is beneficial for germination. Mechanisms include wind dispersal (which dandelion seeds utilize), water dispersal, animals (as in seeds that stick to the fur of an animal and get deposited elsewhere). Some seeds are ejected forcefully from their seed pods by pressure and get transported a distance away from the parent plant. When seeds are dispersed, it helps to maintain species diversity. Therefore, there really is no advantage to the seeds remaining next to the parent plant.