Connie Kingman is a freelance writer. She is an advanced Master Gardener, Master Naturalist and floral designer who enjoys touring gardens around the world.

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The Importance of Pollination
by Connie Kingman    

There are many organisms involved in the process of pollination: wasps, butterflies, moths, flies, beetles, ants, bats and other mammals, including humans. If there were no pollinators, there would be no gardens. Here are some fascinating facts about pollination.


Most flowers reward their visitors with pollen or both pollen and nectar. They also provide nurseries for many insects. Butterflies have taste sensors located on the bottom of their legs, called tarsi. They use the sensors to sample the taste of a flower. If the taste is acceptable, the female lays her eggs on the flower, ensuring a new generation of pollinators.

When Indiana-born song writer Cole Porter wrote, “Birds do it, bees do it even educated fleas do it,” he was writing about falling in love. He could just as well have been writing about pollination, because birds do it, bees do it, and even educated fleas could do it. The lyrics might even have continued for that matter, for there are many other organisms involved in the process of pollination: wasps, butterflies, moths, flies, beetles, ants, bats and other mammals, including humans. We all do it, even if unintentionally. But the most efficient of all pollinators are the bees: honey bees, bumble bees and solitary bees. Their industrious nature leads them on daily treks from flower to flower, transferring pollen amongst them as they go.

The Reproductive
Organs of a Flower

 

The male parts of a flower, called stamens, consist of anthers that produce pollen grains, the male reproductive cells. Anthers usually grow at the ends of thin stalks,  called filaments. 

The female parts of a flower, called pistils, are usually divided into three parts. The ovary is positioned at the base of the pistil, where ovules, or eggs, are produced. The ovary becomes the fruit, while its eggs become the seeds. Above the pistil rises a tube, or style.  At the tip of the style is the stigma. The stigma is sticky to catch and hold the pollen during fertilization.

The pollination story of the yucca plant includes an exclusive partnership with a 1-inch white moth that not only deposits her eggs in the ovary of the bell-shaped flower, but also deposits a gathered ball of pollen, tucked under her chin, onto the tip of the pistil, rubbing the pollen into the stigma to ensure fertilization. The moth does not need the pollen for food for herself or her larvae. She gathers the pollen specifically to pollinate the flower. Later, when the ovary becomes a seed pod, her larvae will feed on the seeds.

We marvel at the beauty of flowers, their intricate designs, their vast array of colors and intoxicating fragrances. Most often, though, we give no thought to their real purpose, which is to produce new plants. A flower is actually the reproductive organ of a plant and positioned within many of them are male parts, called stamens, and female parts, called pistils. For a flower to reproduce, it must be pollinated. In the simplest of explanations, pollination occurs when the pollen from the male part of the flower is transferred to the female part of the flower to produce fruit and seed, a process not far removed from the process of human reproduction.

Flowers employ two modes of pollination: self-pollination and cross pollination. Naturalist Charles Darwin spoke of self-pollination in these words, “Nature tells us, in the most emphatic way, that she abhors perpetual self-fertilization,” which over time, can reduce genetic diversity and weaken a plant to the point of extinction. Healthier plants are produced by cross pollination because this mode produces plants with greater genetic diversity and plants that are able to adapt to environmental changes. Some flowers do self-pollinate, but most depend on other organisms or natural forces to perform this work more efficiently.

Cross-pollination is virtually impossible for most flowers since they are immobile. Conversely, animals and insects are highly mobile creatures, able to search for mates and find food. The image of insects pollinating plants is familiar to us today, but millions of years ago, the process was carried out by natural means such as wind and water. Then, as the animal kingdom expanded from sea to land, a miraculous coevolution resulted. Flowers devised clever ways to accomplish cross pollination by enticing the help of mobile organisms, one way being the production of nectar. The promise of nectar lures organisms into flowers where they sip the sweet liquid. As they burrow in, they brush against strategically placed pollen, which attaches to their bodies and is then carried to other flowers as the organism searches for more nectar. This is why flowers are so varied in size, shape and fragrance: to attract just the right pollinators for the job. 

The process of pollination is an ancient, deeply complex and fascinating system, a system so intrinsically bound to our well-being that if this system were separated from us, our existence would be threatened. Pollination makes possible the reproduction of plants. From plants, we gather armloads of nutritious produce from our gardens. We don aprons, gloves and bonnets spun or woven from plant fiber. We fill our vases with stems of cut flowers. We build benches and trellises fashioned of wood from shade-giving trees. We go about our daily lives, breathing air cleansed and filtered by plants and take pleasure in learning new ways to use plants as food, medicine, utility and craft. We need plants, and pollination ensures their plentitude.

Because pollination happens naturally and literally right under our noses, we often overlook it as a necessary element of successful gardening. Instead, we act as though birds and butterflies were created for our delight. We treat insects as nuisances and complain when wind scatters pollen and causes us to cough and sneeze. If we look beyond ourselves, the miracle of what is really happening becomes clear. These diminutive organisms and natural forces are simply playing their roles in the process of pollination.

My interest in gardening has expanded from nurturing plants to nurturing their partners in pollination. When sitting under my arbor, I hum a little Cole Porter, content just to watch them do it — pollinate, that is!

Buzz pollination, or sonication, is a technique used by some bees to release pollen from a flower by vibrating their wing muscles. The resonant vibration dislodges the pollen from the anthers. Bumble bees excel at buzz pollination.
Apiarist William Robertson of Brownsburg, captured his honey bees returning to the hive in this photo. Note the bees with their hind-leg pollen baskets swollen with golden pollen grains. The bees use this pollen, along with gathered nectar, to feed their young. Pollen is a complete and nutritious food that contains carbohydrates, fats, proteins, vitamins and minerals.

From State-by-State Gardening November/December 2012. Photos by William Robertson.

 

Posted: 02/20/13   RSS | Print

 

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