Corn, or maize, is a staple crop across the globe, and its reproduction often sparks questions about the role of familiar pollinators like bees. The answer is straightforward: bees are not the primary pollinators of corn, which instead relies almost entirely on wind for successful fertilization. This wind-based process, known as anemophily, is a highly effective reproductive strategy for grasses, a family to which corn belongs.
The Mechanism of Anemophily in Corn
The corn plant (Zea mays) is monoecious, bearing separate male and female flowers on the same plant. The male flower structure is the tassel, the large inflorescence that forms at the top of the stalk. The female flowers develop into the ears, which grow lower down on the stalk, encased in husks.
Pollination begins when the tassel matures and releases its pollen, typically over about a week. This pollen falls or is carried by the slightest breeze from the tassel down to the silks, the receptive female parts of the flower. Each strand of silk is connected to a single ovule, which becomes a kernel if successfully fertilized.
For a single ear to form a full cob of kernels, every silk strand must capture a grain of pollen. Wind provides the necessary mobility, creating a cloud of pollen that rains down onto the silks below. This separation of male and female organs, combined with wind transfer, primarily ensures cross-pollination between different plants within a field.
Characteristics of Wind-Dispersed Pollen
The physical and nutritional makeup of corn pollen is specifically adapted for wind dispersal, not insect transport. Corn pollen is produced in massive quantities, with a single tassel capable of generating between two to five million pollen grains. This overwhelming volume compensates for the inefficiency of wind as a vector and increases the probability that enough grains will land on the silks.
Compared to insect-pollinated plants, corn pollen is notably lightweight, dry, and smooth, lacking the sticky, barbed, or oily coating that helps pollen adhere to an insect’s body. Although the grains are relatively large (about 90 to 100 micrometers in diameter), their dry texture allows for easy airborne transport. Wind-pollinated plants also do not produce nectar or have showy, scented flowers, as they do not need to attract an animal pollinator.
The nutritional quality of corn pollen is generally lower in certain nutrients compared to pollen collected by bees from specialized flowering plants. It is often deficient in specific amino acids, such as lysine and methionine, which are important for bee health. This lower nutritional value is typical for anemophilous plants, which prioritize mass production over nutrient density.
Why Bees Visit Corn Tassels
Bees are frequently observed visiting corn plants, leading to the misconception that they are participating in pollination. They are actually engaging in opportunistic foraging, collecting the abundant pollen from the tassels to feed their colonies. Honey bees and bumble bees are polylectic, meaning they gather pollen from a wide variety of plant species, including those with lower-quality pollen, especially when other floral resources are scarce.
The male tassels shed large, easily accessible amounts of pollen, making corn fields an attractive food source. A bee foraging on the tassel releases clouds of pollen as it moves, but this action is incidental to the corn’s reproductive success. Because the female silks are located much lower down on the stalk, the bee’s movements on the tassel do not result in the targeted transfer of pollen to the receptive female parts.
The bees’ foraging activity does not contribute meaningfully to the corn crop’s yield, which is secured by the volume of wind-transported pollen. Corn pollen can sometimes be contaminated with residues from agricultural practices, such as systemic insecticides, which can pose a health risk to the foraging bees. The presence of bees on corn is an act of resource collection, not a necessary step in the plant’s pollination cycle.