Difference Between Self Pollination and Cross Pollination

The key difference between self pollination and cross pollination is that the self pollination is the deposition of pollens of a flower on the stigma of the same flower while cross pollination is the deposition of the pollen of a flower on the stigma of a different flower of the same plant or a different plant of the same species.

Pollination is the process of transferring pollen grains from an anther of a flower to the stigma of a flower. It is an evolutionary important act occurring in plants. There are two types of pollination as cross pollination and self pollination. Self pollination occurs between the anther and stigma of the same flower while cross pollination occurs between an anther of one flower and the stigma of another flower. The article discusses the difference between self pollination and cross pollination in more detail.

CONTENTS

1. Overview and Key Difference
2. What is Self Pollination 
3. What is Cross Pollination
4. Similarities Between Self Pollination and Cross Pollination
5. Side by Side Comparison – Self Pollination vs Cross Pollination in Tabular Form
6. Summary

What is Self Pollination?

Self pollination is one of the two types of pollination in which pollen grains transfer from an anther to the stigma of the same flower or from an anther of one flower to the stigma of another flower of the same plant. Hence, self pollination occurs between two structures of the same flower or the same plant. Annual plants such as barley, peas, vetch, and peanut show self pollination.

Moreover, flowers that show self pollination possess different adaptations to increase self pollination as well as to reduce self pollination. These adaptations enhance self pollination and prevent the chances of cross pollination. Some adaptations include bearing closed flowers, occurring of pollination before the flower opens, presence of anthers on the top of carpals of the flower, etc.

One of the advantages of self pollination is that it does not need pollinators, unlike cross pollination. But, self pollination is not favored since it does not increase the genetic diversity among the plants. Hence, self pollination is not an evolutionary important process.

What is Cross Pollination?

Cross pollination is the most abundant type of pollination in angiosperms since it increases the genetic diversity among the plants. It is the process of transferring pollens from an anther to the stigma of a flower of a different plant of the same species. Hence, cross pollination occurs between two plants of the same species. Most importantly, cross pollination takes place with the help of a pollinator. Insects are popular pollinators.

Also, cross pollination results in cross fertilization. In turn, cross fertilization allows gene flow within a species to produce new genetic combinations while increasing genetic diversity. Hence, cross pollination is an evolutionary important act.

Adaptations for Cross Pollination

Cross pollinating flowers show different adaptations. Normally, they possess a nice colour and a smell to attract pollinators. Some plants show special types of adaptations for cross pollination. One adaptation is unisexuality, which is the presence of different male and female plants. Dichogamy is another adaptation. That is, the maturity of the gynoecium and the androecium of the same flower takes place at two different times.  Dimorphism is another adaptation. Here, some flowers possess short styles and stamens at the mouth of the corolla tube. Other flowers have long styles and anthers attached to the corolla tube below the mouth.

Wind pollinated flowers also show some adaptations to enhance cross pollination. The flowers are small, not coloured, not scented and have no nectar. Stigma is large and feathery. It is normally elevated above other parts. Pollen grains are small, light and produced in large numbers. They are dry with smooth extine. The flowers are simple. They are born on long stalks so that they are elevated above the other parts of the plant. The anthers are versatile. Insect-pollinated flowers also show some adaptations to enhance cross pollination. They are large, brightly coloured, scented flowers with nectar. Stigma is small and sticky while anthers are not versatile. Pollen grains are large and heavy with a rough extine. These flowers show a complex structure.

What are the Similarities Between Self Pollination and Cross Pollination?

• Self pollination and cross pollination are two types of pollination that occur in angiosperms.
• They are essential processes in sexual reproduction of plants.
• In both processes, pollens transfer from anthers to the stigma of flowers.

What is the Difference Between Self Pollination and Cross Pollination?

Self pollination is the process of transferring pollens from an anther to the stigma of the same flower. Whereas, cross pollination is the process of transferring pollens from an anther to stigma of a flower of a different plant of the same species. So, this is the key difference between self pollination and cross pollination. Furthermore, self pollination does not require pollinating agents while cross pollination depends on the pollinating agents. Thus it is a significant difference between self pollination and cross pollination.

Moreover, a further difference between self pollination and cross pollination is that the self pollination is less abundant in angiosperms while cross pollination occurs in ¾ of the flowering plants. Additionally, self pollination does not cause genetic diversity while cross pollination increases genetic diversity. Hence, self pollination reduces the gene pool while cross pollination maintains the gene pool. Therefore this is an important difference between self pollination and cross pollination.

Summary – Self Pollination vs Cross Pollination

Pollination is the process of depositing pollen on the stigma of a flower. There are two main types of pollination: self pollination and cross pollination. Self pollination is the deposition of pollen of a flower on the stigma of the same flower whereas cross pollination is the deposition of the pollen of a flower on the stigma of a different flower of the same plant or a different plant of the same species. Accordingly, self pollination involves a single plant while cross pollination involves two different plants of the same species. Therefore, this is the key difference between self pollination and cross pollination. Consequently, self pollination reduces the genetic diversity among plants while cross pollination enhances genetic diversity. Also, self pollination is not evolutionary important while cross pollination is an evolutionary important process. Thus, this summarizes the difference between self pollination and cross pollination.

Reference:

1. “Pollination.” Wikipedia, Wikimedia Foundation, 4 Apr. 2019, Available here.
2. “Pollination.” Pollination – an Overview | ScienceDirect Topics, Available here.

Image Courtesy:

1. “Self-pollination(1)” By Jankula00 – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Cross Pollination (468246966)” By Snap® from Kuwait, Kuwait – Cross Pollination (CC BY 2.0) via Commons Wikimedia