About Pollination

Pollination is a vital step in the reproduction of flowering plants and involves the transfer of pollen from the male part of a flower to the female part of a flower.

What is Pollination?

Pollination is the process of transfer of pollen from the anthers (male part) of a flower to the stigma (female part) of the flower to enable fertilization and reproduction. Pollination is the first step in a process that produces seeds, fruits, and the next generation of plants. As a key process in sexual reproduction of flowering plants, pollination is crucial both to plant reproduction and to the continued evolution of flowering plants and without pollination, many interconnected species and processes functioning within an ecosystem would collapse. Pollination is also critical to the overall maintenance of biodiversity in many senses. Hence, the majority of cultivated and wild plants depend on pollination to propagate their species.

There are two types of pollination. Self-pollination and cross-pollination.

If pollen is transferred to the same flower as it originated from, it is called self- pollination, and if pollen is transferred from one flower to another flower of the same species, it is called cross- pollination.

Cross-pollination is of importance because it results in viable seed quality, greater uniformity of fruit and vegetable in size, color, taste and volume, and in greater biodiversity as genetics from different individual flowers are combined. However, pollen cannot move on its own, but is accomplished by various agents.

Wind and water as so called natural agents, while pollinating animals such as bees, butterflies and bats are living organisms carrying pollen within and between flowers, seeds and plants.

Animal pollinators

Living organisms are the more numerous of pollinators and honeybees, wasps, flies, moths, butterfly, birds and bats are the most common agents of pollination. Pollination is usually the unintended consequence of an animal’s activity on a flower. The pollinator is often eating or collecting pollen for its protein and other nutritional characteristics or it is sipping nectar from the flower when pollen grains attach themselves to the animal’s body. When the animal visits another flower for the same reason, pollen can fall off onto the flower’s stigma and may result in successful reproduction of the flower. Pollination ensures that a plant will produce full-bodied fruit and a full set of viable seeds. Consequently, pollination is a crucial stage in the reproduction of most flowering plants.

Wind Pollinators

Wind pollinator flowers are often small, have no petals, and no special colors, odors, or nectar. These plants produce enormous numbers of small pollen grains. For this reason, wind-pollinated plants may be allergens, but seldom are animal-pollinated plants allergenic. Their stigmas are usually large and feathery to catch the pollen grains. Insects may visit them to collect pollen, but usually are ineffective pollinators and exert little natural selection on the flowers. Anemophilous, or wind-pollinated flowers, are usually small and inconspicuous, and do not possess a scent or produce nectar.

The anthers may produce a large number of pollen grains, while the stamens are generally long and protrude out of flower. There are also examples of ambophilous (pollinated by two different classes of pollinators) flowers, which are both wind and insect pollinated.

Water Pollinators

The small percentages of plants that are pollinated by water are aquatic plants. These plants release their seeds directly into the water. This is called surface hydrophily, but is relatively rare (only 2% of pollination is hydrophily). Pollen floats on the water’s surface drifting until it contacts flowers. Plants that are water-pollinated usually have small, inconspicuous male flowers that release lots of pollen grains that drift in the water where they are caught by the large, feathery stigmas of female flowers. Some species growing in shallow pools have long, noodle-like pollen that sticks to female flowers. This water-aided pollination occurs in waterweeds and pondweeds. In a very few cases, pollen travels underwater. Most aquatic plants are insect-pollinated, with flowers that emerge from the water into the air.