POLLINATION

POLLINATION

By

Mohd Hanafiah B Said

self-pollination

The transfer of pollen from the anther of a flower to the stigma of the same flower, or to different flowers on the same plant. 

 

  Self-pollination is a form of pollination that can occur when a flower has both stamen and a carpel (pistil) in which the cultivar or species is self fertile and the stamens and the sticky stigma of the carpel contact each other in order to accomplish pollination. The term is inaccurately used in many cases where an outside pollinator is actually required; such plants are merely self fertile, or self pollenizing. Few plants actually self pollinate. The mechanism is seen most often in some legumes such as peanuts. In another legume, Soybeans, the flowers open and remain receptive to insect cross pollination during the day; if this is not accomplished, the flowers self pollinate as they are closing. Other plants that can self pollinate are many kinds of orchids, peas, sunflowers, tridax,etc. Self pollination limits the variety of progeny and may depress plant vigor. However, self pollenizing can be advantageous, allowing plants to spread beyond the range of suitable pollinators or produce offspring in areas where pollinator populations have been greatly reduced or are naturally variable. Pollination can also be accomplished by cross-pollination.

Self Pollination

This type of pollination occurs when the anther and stigma are either in the same flower, or in different flowers on the same plant. As the offspring produced are genetically identical to the parent we can also call it asexual reproduction. To see asexual and sexual reproduction compared in another article click here (will open in a new window). Obviously the genes in one same flower are the same. So this will obviously have to be called self pollination. Something most people mix up is when pollination occurs between different flowers of the same plant. This is also self pollination as the same set of plant genes are involved. So in self pollination either only one flower is involved or the two flowers involved are from the same plant.

Advantages

Self pollination can make sure that a species of plants would not go into extinction as two different plants are not needed to reproduce. If two different plants of the same species are required then there is less chance of pollination happening that often. In other words less offspring produced in cross pollination so there is a higher chance of extinction but plants using self pollination have nothing to fear. They can produce offspring on their own using one parent. The offspring produced are genetically identical to the parent so that means if the parent plant can survive in a certain habitat then the offspring will also surely be able to survive in the same habitat.

Disadvantages

As offspring are genetically identical there is no variation so therefore no evolution. Disease may also easily spread among identical offspring.

Electron micrograph showing pollen grains.

Cross Pollination

Cross pollination is entirely different from self pollination. An important thing to remember is that in Cross Pollination there are always two plants involved. As the offspring are not genetically identical to the parent plant this can be called a form of sexual reproduction. Cross pollination occurs when the two flowers involved are from different plants rather then from the same one. Two flowers from different plants mean that different set of genes are involved. It also very important to remember that the two different flowers involved must be of the same species. So you can also define it in another way. Cross Pollination occurs when the anther and the stigma are in flowers on different plants of the same species.

Advantages

Since offspring are not genetically identical to the parent there are variations and these can lead to evolution. Diseases wont affect all offspring at once as non of them are genetically identical.

Disadvantages

Not a very sure method as the pollen might not reach the stigma. Two parent flowers from two different plants from the same species are required. Cross and self pollination have their own methods, advantages, disadvantages and features. Most of them were simply summarised above. This is all for now about pollination. If you have any questions or suggestions please comment below. If you found this article helpful please support me (Nivu Whatani) by reading my other articles.