Animals, plants, and fungi are the major elements of a community in an ecosystem. These reproduce sexually through different methods. When studying botany or horticulture, specifically plant reproduction, pollination and fertilization always come in the mind. We will discuss the differences between these two terminologies in detail today.
Pollination refers to transferring pollen grains from one flower or plant to another. On the other hand, fertilization refers to uniting male and female gametes to form a zygote. Keep reading the article below to grab more information relating pollination and fertilization.
Comparison Table
| Characteristics | Pollination | Fertilization |
| Definition | Movement of pollen | Fusion of male and female gametes |
| Progression | First | Last |
| Occurrence | Flowering plants | All sexually reproducing organisms |
| Process Type | External | External or internal |
| Dependence on External Factors | Yes | No |
| Transfer Agents | Wind, water, insects | Pollen tube |
| Result | Fertilization | Zygote formation |
What is Pollination?
Pollination is the process where pollens from the anthers of male flowers transfer to the stigmas of female flowers. It leads to the development of new generations of that species. Pollination can also be defined as pollen germination on the stigma. Successful pollination requires the pollen grains to come from the same flower species.
Birds, water, wind, and other elements transfer pollen grains to different plants of a habitat in an ecosystem.
Process of Pollination
The first and foremost step in the sexual reproduction of flowering plants is transfer of gametes through pollination. The male gamete is inside the pollen grains, which are present in the flower’s anthers.
The pollination process depends on the mechanism of pollen grains landing on the stigma and combining with the style’s length that connects the stigma to the ovary. Upon completion of the pollen tube, the pollen grain transports sperm cells from the grain to the ovary.
Types of Pollination
Plants can either reproduce sexually or asexually, but flowering plants only undergo sexual reproduction through pollination. Self-pollination and cross-pollination are the two fundamental types of pollination. Self-pollination is the most common type, while cross-pollination is somewhat complicated.
Self-Pollination
Self-pollination is the most basic form of pollination because it requires only one flower. Pollen grains self-pollinate when they travel straight from anthers to stigmas. Because the sperm and egg cells of the flower share some genetic information, this procedure is effortless and quick. However, it does not give rise to genetic variation.
Pollination in self-fertilizing plants is less reliant on environmental factors. These plants can’t survive without the regular visits of wind or other smaller insects. To facilitate the transfer of pollen, the anthers and stigma of self-pollinating flowers are the same lengths. It is possible to classify self-pollination into two subtypes: autogamy and geitonogamy. During autogamy, pollen grains move from an anther to a stigma within the same flower. At the same time, pollen grains transfer from one flower’s anthers to another flower’s stigmas during geitonogamy.
Cross-Pollination
Cross-pollination occurs when pollen grains move from one flower’s anther to the stigma of another. In this process, various flowers can exchange and mix their genetic information to make unique offspring, increasing genetic variety. In all cases, an external factor is essential for cross-pollination. Biodiversity also plays a major role in the transfer of pollen grains. Birds, animals, water, wind, and insects are all factors in the pollination process.
Cross-pollination typically occurs in colorful flowers whose aroma attracts bees. Lavender, dandelion, apple, and strawberry are examples of cross-pollinating plants. In addition, there are a few types of cross-pollination depending on the involvement of pollinating agents. Abiotic cross-pollination transfers pollen grains from one flower to another through abiotic factors such as wind and rain.
Anemophily or pollination by wind accounts for approximately 98% of abiotic pollination. Most likely, insect pollination (entomophily) causes this pollination as a result of environmental changes or the availability of pollinators. Hydrophily or pollination by water involves the transfer of pollen from one flower to another over the water’s surface. Sometimes, the anthers are pollen carriers, making the journey across the water.
Biotic cross-pollination is the transfer of pollen grains from one flower to another by animals, insects, and birds. Zoophily, zoogamy, or pollination by animals, such as humans, bats, birds, and others, serves the purpose of pollinators in this method. Pollen from zoophilous flowers is sticky enough to stay on the animal’s fur or feathers, allowing the flower to move to another location.
What is Fertilization?
Fertilization is the process that forms a diploid zygote from uniting female and male gametes and follows carpel pollination. Fertilization in plants may occur within the same plant or between plants in distant niches within the same habitats. Sometimes, the pollen grains carry the genes and alleles to far-away areas.
Process of Fertilization
The process of fertilization occurs following pollination. Each sperm and egg has fifty percent of its genetic material, which combines to form a new plant. When the pollen particles come in contact with the stigma, a small tube containing sperm originates. In addition, the tube inserts into a second pipe-like structure called the style of the female pistil.
It extends from the style to the aperture of the ovary, where sperms gather. A zygote or plant seed develops when the sperm and egg completely fuse and fertilize the egg. The process of fertilization can be explained through four steps:
- Pollination
- Germination
- Ovule penetration
- Fertilization
Types of Fertilization
Fertilization can be divided into various categories depending on the type of plants and method. Gymnosperms and angiosperms exhibit fertilization in specific ways.
- Gymnosperms, or seed plants, produce their offspring on both sides of their leaves or scales, in cones, or at the tips of short stalks during fertilization. The ovary keeps the seed safe and sound inside.
- Extra fertilization occurs in the flowering plants’ center cells, Angiosperms. Each pollen particle releases two sperm cells. Fertilization of an egg requires the first cell to fuse with the zygote, while the second cell’s fusion with the two polar nuclei results in the endosperm formation.
The fertilization methods depend on how pollen tubes reach the ovule or embryo sac.
Porogamy
All angiosperms or flowering plants fertilize this way. The pollen tube enters the ovule through the micropyle. Lilies are examples of porogamy.
Chalazogamy
Casuarina species plants fertilize in this way. Instead of a micropyle, the pollen tube enters the ovule through the chalaza. It’s a rare occurrence. Casuarina, Betula, and Juglans follow chalazogamy.
Mesogamy
The pollen tube penetrates the ovule through its center or integuments in mesogamy. This fertilization is standard in pumpkins, ridge gourds, bitter gourds, and other gourds.
Double Fertilization
It occurs when two male gametes fuse with a female gametophyte. One sperm cell unites with the zygote to create an egg, and the other fuses with the polar nuclei to form an endosperm. Every angiosperm plant reproduces sexually twice.
Difference Between Pollination and Fertilization
Definition
Pollination
Pollination refers to the movement of pollen from the anther to the stigma of a flower.
Fertilization
On the other hand, fertilization is the process that forms a diploid zygote from uniting female and male gametes.
Occurrence
Pollination
Pollination occurs only in flowering plants and takes place before fertilization.
Fertilization
However, fertilization happens after pollination. It takes place in all sexually reproducing living beings, including plants.
Process Type
Pollination
It is an external and physical procedure to transfer pollen grains.
Fertilization
In contrast, fertilization can be internal or external; however, it’s a genetic and biochemical approach.
Dependence
Pollination
Pollination depends on external factors.
Fertilization
On the other side, fertilization requires no external factors.
Results
Pollination
Pollination leads to fertilization in flowering plants.
Fertilization
Whereas, fertilization leads to the development of seeds and embryos.
Transfer Agents
Pollination
The wind, insects, water, and other agents all play a role in pollination.
Fertilization
Conversely, the pollen tube plays the role of an agent entering the ovule.
The Bottom Line
Pollination and fertilization are critical to plant reproduction. They ensure the transfer of DNA and genes to facilitate reproduction. Pollination occurs before fertilization resulting in the transfer of genetic material. After pollination, the pollen grains fertilize the eggs in the ovules of the flower. External factors like wind and insects often contribute to pollen grains’ movement to distant flowers. However, sometimes, they fertilize the same flower.
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