Pollination is the process which plants undergo to be able to reproduce sexually. The process of pollination consists of the following: the transfer of the pollen grains or the male germ cell from the stamen of the plant to the stigma; as the pollen is transferred to the stigma the pollen then grows into a tube from the stigma down to the style to the female germ cell. Pollen grains of different types of plants may be viewed through the microscope. Before the flower of a plant bear its seeds, pollination must take place. Practically, this process occurs in every plant; before the plant bear seed. The bearing of the seed signifies the growth of a fruit. Seeds may be used as specimen to be viewed with the microscope. A seed develops and while it grows, the tissues surrounding it swells and forms the fruit of the plant.

Most plants reproduce through cross-pollination. This process takes place when the pollen of a flower is transferred to the stigma of another flower. There are two factors that enables plant to pollinate. These two ways of transfer is by wind or through insects. Only a few of the higher plants reproduce by means of self-pollination. Plants which pollinate through the wind is able to produce a large quantity of dry pollens which are blown by the wind far and wide. This wind pollinated plants reproduce when afew of the millions of pollen grains they produce happen to land on the stigma of the right flower. Plants which pollinate with the aid of insects produce less pollen grains.

The pollen grains that is produced by insect-pollinated plants is usually sticky and stays to the bodies of insects that visit the flower. Later, the pollens that adheres to the insects’ body is rubbed off onto the stigma of another flower which the insect visit next. This phenomena is more or less done by insects by accident.
The peculiarity of many flowers’ feature or structure is a great help in ensuring reproduction through pollination. For, instance, the flower such as the iris are so uniquely constructed that it will be impossible for the insect to get into the nectar without the pollen grains sticking on its body and it cannot enter into another flower of the same kind without leaving some of the pollen it collected on the stigma. Pollinia are special masses of pollen grains. The masses of pollen grains can be clearly viewed and oberved under a microscope. Milkweed is an example of a plant having pollinia. These special pollen masses are arranged in such a way that an insect lands on the edge of the flower slipping its legs into fissures in the pollinia. The pollinia is then stucked on the insects’ body and carrying it into te next flower.

Some plants such as some orchids are dependent on a single type or species of insects to pollinate them. Only a certain long-tongued hawk moths are the insects which can pollinate some orchids. The fig wasp (Blastophaga psenes) is responsible for the pollination of the Smyrna fig while the yucca moths (Tegeticula) pollinates the yucca plant. The fig wasps and the yucca moth can be studied with the microscope.

Plants such as timothy, corn, rye, oats, wheat and grasses are not dependent on insects for their pollination. Wind-pollinated plants also include trees such as the conifers, birches, poplars, elms, oaks, willows, and hickories. Wild plants which are wind-pollinated and does not need insects to pollinate them are rag weed and pigweed. Many plants on the other hand are dependent on insects for their reproduction. Insect-pollinated plnts include orchard fruits such as blackberries, strawberries, blueberries, cranberries, cherries, plums, pears, apples and other citrus fruits. Field crops such as clovers and tobacco are also insect dependent. Vegetables such as carrots, cucumbers, melons, pumpkins, squash, cabbage and onions pollinate with the aid of insects. Many flowering plants are insect-pollinated.

Various species of bees, chiefly honey bees and bumble bees are responsible for pollinating clovers. Honey bees may be studied with the use of the microscope. Apples, pears, cherries, blackberries and strawberries are ro saceous plants which solely depend on honey bees for pollination. Bees are not the only insects thatpollinate flowers. Plants such as honeysuckle, tobacco and petunias are also pollinate by moths other than the bees because of the strong smell. Carrots and parnips are examples of umbilleferous plants which are pollinated mainly by flies, bees and wasps. Certain species of beetles and bees pollinate some other flowers including lilies, goldenrod and many more.