WHEN springtime comes around, bees get busy and pollen fills the air. For people who suffer from allergies, pollen seems to be a curse rather than a blessing.
But before we dismiss pollen as just a nuisance of nature, we should keep in mind the role this unique dust plays. We may be surprised to learn how much our lives depend on it.
What exactly is pollen? Pollen consists of tiny grains that are produced in the male organs of flowering and cone-bearing plants. Simply stated, plants produce pollen in order to reproduce. As we know, in humans a female egg must be fertilized by a male sperm in order for a child to be produced.
Similarly, the female organs of a flower [the pistil] need pollen from the male organ [the stamen] in order to be fertilized and produce fruit. Fertilization can be either by cross-pollination [pollen delivered from another plant] or self-pollination [pollen received from the same individual plant]. Nevertheless, cross-pollination guarantees variety and thus healthier and more resilient plants.
Pollen grains are so tiny that we can hardly see them with the unaided eye; however, they become apparent under a microscope. In fact, a viewer can see that both the size and the shape are unique to each particular species. Since pollen is resistant to decay, it is significant that scientists often study the unique “fingerprint” of the pollen grains they unearth.
They can thereby identify plants that people cultivated centuries ago. Importantly, the distinct characteristics of each type of pollen enable flowers to recognize the pollen of their own species.
THE WAY POLLEN TRAVELS
Many plants depend on the air to transport their pollen after it is released from catkins or cones when they are jostled by the wind. Water also serves to transport the pollen of some water plants. Since wind pollination is a hit-and-miss affair, trees and plants that depend on this method of pollination produce astronomical quantities of pollen.
Just one birch catkin, for example, may release over five million grains of pollen, and a typical birch tree will likely have several thousand catkins.
For people who suffer from hay fever, this proliferation of pollen results in great discomfort.
Although wind effectively helps to pollinate many types of trees and grasses, flowering plants that do not grow in high densities need a more efficient system. How is the pollen from such plants dispatched to other like plants that live kilometers away?
By a very effective delivery service provided by bats, birds, and insects! But, of course, they don’t transport pollen from one flower to another without a reward.
Flowers offer these pollinators nectar –a tasty product that is hard for them to refuse. While reaching to sip the nectar, the visitor invariably gets a good dusting of pollen on its body. Seeking another taste of nectar, it then transports the pollen to the next flower.
Insects do by far the most pollination, especially in temperate lands. They visit countless flowers every day while feeding on nectar and pollen. One kilogram of honey requires that bees make about ten million trips to individual flowers.
Probably the most important contribution made by insects to human health and well-being, is one for which they get little credit: pollination. Fruit trees usually have flowers that depend on cross-pollination to produce a good crop. Hence, you can see how important the transportation of pollen is to our well-being.
HOW THE WORKERS ARE ENTICED
Flowers have to attract potential pollinators as well as feed them. How do flowers do this? They may provide pollinators with a warm resting place in the sun. They also advertize their wares, usually by their pleasing appearance and smell.
Also, many flowers lay out some helpful guidelines in the form of colored spots or stripes. In this way visitors are informed where they can find the nectar.
Advertisements vary greatly from one flower to another. Some exude a smell of putrefaction to attract flies. Others resort to trickery to ensure successful pollination. Bee orchids, for example, look like bees, and that fools amorous bees into visiting them.
Certain flowers capture insects and release them only when the insects have performed their pollination duty. Nowhere in the plant kingdom is botanical engineering more delicate, more precise or more ingenious than in the vital matter of ensuring that flowers are pollinated.