Story by George Ellison with illustration by Elizabeth Ellison
In order to accomplish pollination, flowering plants have been outwitting, beguiling, and utilizing insects for millions of years. One of the more interesting insect-flower relationships was forged between mountain laurel and its insect visitors.
As we are presently in the midst of the mountain laurel flowering season (common April-June below 5,000 feet on dry slopes) this overview will hopefully help you appreciate the association more fully when you encounter it in the wild.
Each of the inch-wide pinkish-white flowers that comprise the 4-5-inch-wide flower clusters displays 10 small pockets in which male pollen-bearing anthers are inserted. These are, in essence, spring-loaded via tension created by attachment to long strands of filament.
The stage is set. All that's required, in daylight, is a hairy bumblebee or, at night, a wooly white moth. Attracted by the mountain laurel's fragrance, their efforts to access nectar will release the spring mechanism. Pollen is literally catapulted onto the insect, where some of it adheres due to the critter being either hairy or wooly.
As the insect moves from one mountain laurel shrub to another, some pollen will often rub off on another flower's pistil, thereby ensuring cross-fertilization. But what if no pollen is deposited on a given mountain laurel flower's pistil? Well, there is a backup plan for self-fertilization whereby a plant's filaments lose their tension, so that the pollen is deposited on its own stigma.
Do it yourself. Using a pencil, dislodge the anthers in a mountain laurel flower from their little pockets and watch the pollen fly.