Plants disperse their seeds with the help of wind and water, animals and force from the plant itself when the seed pod bursts open. It is important that seeds move away from the mother plant so that the plants do not become overcrowded.
Because plants are rooted to the ground, they have evolved with a variety of different seed dispersal methods to propel seeds some distance away from the parent plant. Many of these methods involve helpers, such as the wind. Some plant seeds have developed specialized parts designed to catch the wind. Dandelion seeds are lightweight and have fluffy tops so that they can be carried great distances. Maple seeds have helicopter-like wings that twirl them away from the parent tree on a windy day. Moving water helps disperse the seeds of plants that live in or near the water. Seeds drop off into the water flow and are carried away.
Other plants have evolved seeds with characteristics that allow them to be easily dispersed by animals. Seeds encased in tasty fruits are eaten by animals and then dispersed to another area in the animal's droppings. Some seeds, such as burdock, have prickly cases that attach to an animal's fur to be dispersed as the animal moves about. Peas and beans grow in pods. When the pods are overfull, they burst open. The force propels the seeds some distance from the plant. The peas and beans round shape also encourages rolling for more distant dispersal.