Life Cycle of Sweet Corn

Image by, courtesy of Amanda

Grown everywhere on earth except Antarctica, corn is a prominent cash crop. Seventy-five per cent of everything you find in a grocery store has some form of corn in it, from an ear of sweetcorn to a can of soda to the paper bag you carry your "corny" groceries home in. Corn is involved in the production of hamburgers, pork chops, and chicken wings, since fully half of corn grown goes to animal feed. No matter where corn ends up, it all starts out the same way, as a seed that grows into a towering tasselled plant.


You may be familiar with the story of how 17th century Native Americans taught the Pilgrims how to grow corn---planting five corn kernels and five herrings (for fertiliser) in a mound of earth---but corn actually originated in Mexico 7,000 years earlier. The cultivation of corn spread with the trade routes and today corn is a valuable crop around the world. In addition to human and animal food, corn is a sweetener, starch used in paper products and cooking, and the key ingredient in ethanol, a sustainable renewable fuel for automobiles.


A sweetcorn plant is made up of several parts---the kernel (or seed), the roots, the prop root, the stalk, the lower and upper leaves, the ear (which is made up of the cob, kernels, silk and husk), and the pollen-bearing tassel on the top of the plant. Each of these structures emerges at different stages in the life cycle of sweetcorn.

The Kernel

The seed of a corn plant is called a kernel. On average an adult ear of corn has 16 rows with 50 kernels in each row. As both the seed and the fruit, the kernel stores energy and either provides food to humans, animals, birds, and insects, or acts as the starting point of another generation of corn plants. In this way, the kernel is at the beginning and at the end of the life cycle of sweetcorn.

The Plant

Once a planted kernel sprouts, the corn plant begins to grow. Part of the kernel sends roots into the ground seeking nourishment, while the other part develops into a prop root, a strong structure that holds the 7 to 10 foot tall plant upright. A sturdy stalk develops on which about 15 blade-shaped leaves emerge. An average of two ears of corn grow on each stalk, while a tassel containing essential pollen appears at the very top. It takes about 120 to 150 days for a corn plant to become fully adult.


Each kernel on an ear of corn has a silky thread that runs up the corn cob and peeks out the husk. Each of these strands of silk must be pollinated by pollen from the tassel at the top of another plant or a kernel will not form.

Because corn is pollinated by the wind, the most efficient way to plant corn is to place it in several parallel rows instead of one long one. In this way the wind can disperse the pollen from the tassel of one plant to the surrounding corn plants.

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