In the fall, helicopter sugar maple seeds brush your face as they spiral downward towards leaf-covered ground. “Sticktight” beggars cling to your clothes as you explore an ACRES preserve near you. These seeds are the result of a partnership that has remained intact without a legal contract for millions of years … a partnership between plants and their pollinators.
Most flowers need outside help to achieve pollination. At the same time, pollinators like insects, birds and bats need flowers for food. This reciprocal partnership has resulted in a wide variety of pollinator adaptations and plant attractant strategies.
Most insect groups have evolved unique body structures to harvest a flower’s nectar. An insect’s collecting nectar and, inadvertently, pollen, is similar to fitting a key into a lock. While some insects (such as honeybees) can extract nectar from a wide range of flowers, others are specialists with specific needs.
Insect species’ mouth parts vary, some adapted for only one particular plant structure. For example, butterflies use a long, thin feeding tube (proboscis) to suck nectar by capillary action from small, tubular flowers. Because many species of fly pollinators have short, round mouth parts that act like sponges, they prefer wide-open flowers. Other pollinators such as moths seek a flower such as evening primrose that opens at night when moths are most active due to their keenly adapted night vision.
One very specialized partnership between pollinator and plant directly determines the plants’ blooming schedule. The delicate Dutchman’s breeches wildflower opens in early spring. The emergence of its bright white blossoms (resembling rows of tiny pants hung upside down to dry) coincides with the emergence of overwintering queen bumble bees.
As the queen bees emerge from hibernation, they bump along the ground in woodlands searching for appropriate nesting sites in abandoned holes, leaf piles or other dry locations. Low-growing Dutchman’s breeches’ blossoms provide a perfect nectar-rich and protein-rich pollen source for a queen bee’s newly constructed nest site. And the queen bumble bees have the right tongue size, length and strength to pry open the upside-down petals on these unusually-shaped wildflowers.
Plants have a number of creative ways to attract pollinators. Plant species that rely on insects for pollination emit a full range of fragrances, from the sweet smell of yellow sweet clover in the fall to the carrion smell of skunk cabbage in early spring. Many flowers use nectar guides or “landing patterns” to direct insect pollinators to nectar sites.
Most commonly, flowers intensify their attractiveness by displaying bright, showy colors. Since most pollinators fly, a flower’s colors must attract them from a distance. Thus the brighter the flower, the more likely it will be visited. Shades of red signal a high concentration of nectar.
Adaptations responsible for the glorious colors we associate with fall are byproducts of selective coloration. To decrease competition and provide pollinators with a constant food supply, plants have evolved differing flowering times during their growing season. As the seasons change, different species of insects are busy seeking nectar.
Insect color preferences determine which flowers are blooming during each season (or is it the other way around?!).
Observe in the Field
Want to compare plants’ color adaptation and the subtle change in colors in a spring and fall landscape?
- This fall before visiting an ACRES’ preserve, get paint chips/swatches in deep color ranges of blooming flowers, such as deep purple, golden yellow, and sharp red.
- In the preserve, match the paint chips with the blooms and write dates, preserve name/location on each chip.
- Next spring, get a second set of paint chips/swatches that best match spring-blooming flowers, such as soft pink, light purple and mellow yellow.
- Again, mark each color match with date and location.
- Finally, lay the two sets of color patches beside each other. Subtle and dramatic—shade differences for each color family are not accidental. Without these differences, we wouldn’t be able to look forward to spring’s soft colors or fall’s rich, deep colors. Go out and enjoy nature’s colorful palette!
Reprinted from the Summer Quarterly. Written by Pam George.