Wednesday, September 29, 2010

Pollen The Dust of Life

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? The World Book Encyclopedia explains: “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 organ of a flower (the pistil) needs pollen from the male organ (the stamen) in order to be fertilized and produce fruit.*

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.# 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 miles 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.% “Probably the most important contribution made by insects to human health and well-being,” explains Professor May Berenbaum, “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.

The Pollinators

These are some of the unsung heroes of pollination. If you enjoy chocolate, you can thank a tiny fly that does the vital job of pollinating the flowers of the cacao tree.

A number of the world’s most majestic trees, such as the kapok and the baobab, depend on bats for pollination. Some fruit bats not only feed on nectar but also eat the fruit and disperse the seeds, thus performing a double service. In Australia small marsupials known as possums visit flowers to feast on nectar. During the course of their visits, their furry bodies transport pollen from flower to flower.

These attractive insects depend largely on nectar for food, picking up pollen as they fly from one flower to another. Some beautiful orchids depend entirely on moths for successful pollination.

These colorful birds constantly flit from flower to flower, sipping nectar. Pollen gets deposited on the feathers of the birds’ forehead and breast.

The hairy bodies of bees pick up pollen as readily as a pair of spectacles picks up dust, making bees ideal pollinators. Just one bumblebee can carry as many as 15,000 grains of pollen. Thanks to the introduction of bumblebees from England in the 19th century, clover fields now flourish in New Zealand, providing vital forage for the country’s livestock.

The honeybee is the world’s most important pollinator. It usually concentrates on only one type of flower abundant near its hive. Entomologist Christopher O’Toole calculates that “as much as 30 per cent of all human food is directly or indirectly dependent on pollination by bees.” Bees are needed to pollinate such crops as almonds, apples, plums, cherries, and kiwis. Farmers pay the beekeepers for the services each hive provides.

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 advertise 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,” writes botanist Malcolm Wilkins.

If the Creator hadn’t arranged for the pollination of plants by making them attractive, millions of plants would not reproduce. Commenting on the result of that remarkable activity, Jesus said: “Take a lesson from the lilies of the field, how they are growing; they do not toil, nor do they spin; but I say to you that not even Solomon in all his glory was arrayed as one of these.”—Matthew 6:25, 28, 29.

Thanks to pollination, plants thrive and produce the food on which we depend. True, pollen may cause discomfort to some of us, but we should all be thankful for the busy pollinators that distribute this dust of life. Successful harvests depend to a large extent on this marvelous natural process that testifies to the amazing handiwork of our Creator.

* 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.

# 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.

% Two pounds of honey requires that bees make about ten million trips to individual flowers.

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