Pollen is the product of the male reproductive system of a plant and needs to be dispersed, ideally, away from the parent plant. This pollen dispersal increases genetic diversity, protects the species from extinction and reduces the competition between the plants for resources. A number of agents are used for the dispersal of pollen. Many flowering plants use bees and other insects for pollen dispersal. Some other plants may use birds for pollen dispersal. These pollinators (the organisms that causes pollination by dispersal) need to be attracted towards the pollen source. That is why many plants produce nectar. Wind and water are known agents of pollen dispersal. Wind can carry the pollen great distances. Similarly, any pollen that falls into water can also be carried away to distant regions. This increases the chance of pollination of a flower farther away, increasing the odds of the seedlings growing in some region far away from the parent plant. This will give both plants greater access to resources without competition between the parent plant and seedling.

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What helps disperse pollen grains to another place?  

Pollen is essentially the "male" reproductive cell of a plant. In order to produce seeds, it must travel to the "female" part of the plant, the stigma, where it can travel down the pistil to the ovule, and produce a seed. The seed then has the correct number of chromosomes to produce a new plant.

Some plants self-pollinate; the pollen fertilizes the female part of the same plant that produced it. But for others, the pollen must travel to a new plant, which may be quite far away. There are several ways this can happen. The wind can carry pollen to new plants. People can intentionally pollinate plants in order to cross the particular plants they want. Many plants rely on some type of animal pollinator. These plants tend to be brightly colored or have a strong smell, in order to attract the pollinator. Bees, butterflies, moths, flies, hummingbirds, and even bats can act as agents of pollination. They are attracted to a plant because of its color, smell, or both. While visiting the plant, they pick up the sticky pollen from one, which they then carry to the next plant they visit. The seeds can then be formed as the pollen is deposited on the stigma of another plant.