Pollination is defined as the transfer of pollen from the anthers of a flower, to the stigma of the same or another flower. It is also known as a prerequisite for fertilization. Fertilization however, is known as the process of fusion of nuclei from the pollen grain with the nuclei in the ovule, allowing the flower to develop seeds. There are two main types of mechanism, viz., self and cross pollination. Self pollination is the process in which the flowers develop seeds, as a result of the pollen and the pistil from the same plant fusing together in fertilization. Whereas cross pollination occurs, when the pollen and the pistil are from two separate plants and they fuse to give a seed. There are many modes in which this unique phenomenon occurs, which is through wind, animals, insects, etc., out of which the most common are wind and insects.
Pollination is studied in a number of disciplines such as botany, entomology, ecology, and horticulture. The carriers of these pollens, from the male gamete to the female gamete, are often known as vectors or pollinators. The entire industry of horticulture and agriculture depends on this phenomenon, which results in the reproduction of plants. There are two types, abiotic and biotic.
This is the most common type that occurs in nature, and the biotic carriers are called pollinators. In this process, the organisms which visit the flowers for nectar, carry these pollens, which stick to their bodies, to other plants. These pollen then, may or may not fertilize with the stigma of the new flower to produce seeds. There are two ways that occur due to biotic factors. The first one is, Entomophily, where the pollinators are insects, like bees, wasps, butterflies, moths, and ants. The second is Zoophily, wherein the pollinators are vertebrates like birds and bats.
This is the less common type, which occurs only in 10% plants without animal assistance. The most common of this type is the anemophily, which occurs through wind. This method works for various grasses and many deciduous trees. Hydrophily is also another way, which occurs through water. This can occur for aquatic plants, which release their pollens directly into the surrounding water.
As mentioned earlier, there are two mechanisms, which are self and cross pollination. In self pollination, the pollens of the same flower or the flowers of the same species, are fertilized with the stigma. This type can occur via the above mentioned pollinators. Cross pollination or allogamy, however means, the pollens of one particular flower are delivered to a completely different plant. It is also used in horticulture for hybridization of many varieties of flora and fauna.
Thus, pollination is mainly used to come up with new varieties of flora and fauna. It is a necessary function for the growth, reproduction, and evolution, of all plant species in the world.