By Ranger Steve Mueller
Showy attractive flowers tend to be insect pollinated. Flowers that do not capture our attention are typically wind pollinated. The size of pollen is a critical factor between the wind and insect pollinated flowers. Large pollen weight causes it to fall to ground near the parent plant when dislodged. An insect or bird is needed to carry heavy pollen from flower to flower in order for the plant to have successful fertilization. Tiny pollen is easily carried long distances by wind to improve chances for pollination.
When a bee, butterfly, beetle, other insect, or hummingbird carries pollen from one flower to another, the pollen sticks to the top of a pistil if it is ripe and receptive. Male pollen is equivalent to sperm in animals. When it is released from a flower’s anther, an animal carries it to another flower. Animals that carry pollen improve the chances for pollination because pollen on their bodies has the best chance of reaching a flower of the same species. Wind carried pollen rides the wind wherever it goes.
We notice yellow pollen on a honeybee’s body. Showy flower petals attract the attention of insects. When insects approach a flower, they see “lighted runway” landing strips. They are not as noticeable to our eyes because petals reflect ultraviolet light we do not see. Insects see a broader visible spectrum. We might see dark or light lines on the petals that lead toward the center of the flower.
Those lines are runways that direct the travel of insects like airport runway lights help a plane’s pilot on the landing strip. As the insect walks toward the center of a flower to probe for nectar, it brushes against an anther that sits atop a thin string-like filament that bends when bumped. If the anther is ripe, pollen will be released onto the body of an insect and sticks to its “hairy body.”
The female part of the flower usually ripens later than its flower’s anthers and is not receptive when the pollen is released. This helps prevent inbreeding. The part of the flower pistil that captures pollen has a sticky top called the stigma. Pollen on it digests its way through a long neck called the style and when it reaches the ovule (egg) in the ovary it will fertilize it. The fertilized ovule becomes a seed.
The same process occurs in wind-pollinated flowers like corn, grass, sedges, and ragweed. Ragweed blooms at the same time as showy yellow goldenrod flowers in a field. The pollen on goldenrod is large and fewer in number than minute pollen cells released from ragweed. Goldenrod pollen will not be carried far by wind and falls to the ground. It is insect dependent for pollination. Ragweed pollen, like corn pollen, can float in a gentle light breeze. It will go wherever the wind goes and is less efficient at reaching a flower of its own species. More pollen is produced by wind-pollinated plants and compensates for the lower efficiency.
Pollen from the nondescript green ragweed flowers makes it to our nose and sinuses where it causes an allergic reaction we call “hay fever.” People unjustly blame goldenrod for “hay fever.” Goldenrod pollen is unlikely to get in our noses unless a bee enters our nose. If that occurs, the bee will be of greater concern than the pollen.
Some insect pollinated flowers are green but the insects find them. I wonder if they reflect ultraviolet light. Some flowers can utilize both wind and insect pollination. How I wish I knew more about the secret workings in nature niches. There is always something new to discover outside. Do not blame the insect-pollinated goldenrod for “hay fever.”
Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at firstname.lastname@example.org – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.