What is pollination?
“More than 90 percent of the world’s wild plant species and 75 percent of cultivated crops are aided by pollinators in their seed production” - Swedish Environmental Protection Agency
Pollination occurs when grains of pollen from the stamen (a flower’s male reproductive organ) are transferred to the stigma of the pistil (the female reproductive organ). The pollen grain germinates on the stigma and extends a pollen tube down into the pistil to fertilise the ovules in the flower’s ovary at the base of the pistil. This results in seeds developing, as well as fruit flesh, which provides the seeds with nourishment. You can see a picture here
Some plants are self-fertile, which means that fertilisation can occur inside the flower. Examples include wheat and barley. Other plants have to have their flowers fertilised by another flower of the same species in order to grow properly, even if they are self-pollinating. This is known as cross-pollination. Examples include apples, carrots and strawberries. The advantage of cross-pollination is that it results in greater genetic variation, which helps the species survive in a changing world.
Pollen can be transferred from the stamen to the stigma in various ways. Wind, water and insects are the main factors for successful cross-pollination.
The pollen of some plants, such as pine and spruce, which produce large amounts of tiny pollen grains, can be transported by the wind for tens of kilometres. Grasses such as timothy grass and maize are wind-pollinated.
Many plants, such as various types of berries and fruits, depend on insects, which can have an action radius of up to 500 metres. In order to cross-pollinate and grow successfully, plants need the right pollen. Apple trees need pollen from other apple trees, wood anemones need pollen from wood anemones, strawberry blossoms from strawberry blossoms, and so forth. When an insect flits from flower to flower, it transfers pollen grains between the flowers.
To get the right pollen, different plants have developed a variety of strategies to attract insects. For example, different plants produce nectar at different times of day, or they may have different colours or scents, or their nectar may be stored at a depth that can only be accessed by long-tongued insects. The variety is enormous, so it is also important to have a wide variety of wild pollinators.
If a plant lacks the opportunity for adequate pollination, for which it may depend on a certain species, it may become extinct. Our ecosystem is a complex web of interactions.
The food we eat depends directly or indirectly on some form of pollination, whether that food consists of a plant’s root, as with carrots, beetroot or peanuts, or parts of the stalk or leaves, as with cinnamon, cane sugar, herbs or spices. We also eat the seeds of plants, such as wheat, maize, nuts, or the fruit around the seeds, as with applies, tomatoes or cucumber. Or we might eat the part of the fruit that the seeds are attached to, as with strawberries.
What would your breakfast look like without pollinators? And what would nature look like?
