Why Does Corn Silk Match the Number of Kernels?

Why Does Corn Silk Match the Number of Kernels?

Each strand of corn silk corresponds to one kernel on the cob, because each silk strand is the stigma — the pollen-catching part — of a single female flower. An ear of corn is not one fruit but a cluster of hundreds of individual female flowers, each of which produces one kernel if successfully pollinated. Each flower sends out one silk strand to catch pollen, and that strand is the pipeline through which the pollen travels to fertilise the egg and form the kernel. No silk, no kernel. Every kernel on the cob has its own silk.

This is one of those botanical facts that sounds surprising until you think about it, and then it makes perfect sense. Corn is a grass — a giant grass — and like other grasses it is wind-pollinated. The male flowers are at the top of the plant (the tassel), and the female flowers are on the ear, with their silks dangling out the top of the husk to catch wind-blown pollen. Each grain of pollen that lands on a silk strand travels down the inside of the strand to the egg at the base, fertilising it and starting the development of a single kernel.

How Corn Pollination Works

Corn is monoecious, meaning each plant has separate male and female flowers. The male flowers are the tassel at the top of the stalk. They produce millions of pollen grains that are released into the wind over several days. The female flowers are the ears, which develop on the side of the stalk lower down. Each ear contains rows of female flowers, and each female flower produces a long, thread-like silk that grows up through the husk and emerges at the top to catch pollen.

When a pollen grain lands on a silk strand, it germinates and grows a microscopic tube down the inside of the silk — a journey of up to 30 cm that takes about 24 hours. The pollen grain's genetic material travels through this tube to the egg at the base of the silk, where fertilisation occurs. The fertilised egg then develops into a kernel over the following weeks. Each kernel is therefore the product of one silk, one pollen grain, and one successful fertilisation.

If a silk strand does not get pollinated — if no pollen lands on it, or if the pollen does not successfully travel down the strand — no kernel develops at that position. This is why you sometimes see ears of corn with gaps or missing kernels: the silks at those positions did not receive viable pollen. Poor pollination is often caused by dry conditions (silks dry out and are less receptive), hot weather (pollen dies quickly in high temperatures), or poor wind at the time of pollen shed.

Why an Ear of Corn Has So Many Silks

A single ear of corn typically has 400–800 kernels, arranged in rows. Each of those kernels had its own silk. When you husk an ear of corn and see the mass of silk at the top, you are looking at the collected stigmas of every female flower on that ear. The silks are not a single bundle — each one is an individual strand that connects to one specific position on the cob.

This is why the silk is so tangled. Each strand grew independently from its own flower toward the top of the husk, competing for space. By the time they all emerge, they are a mass of hundreds of individual strands, each one a potential pipeline to a kernel. The next time you husk corn, try counting the silks and the kernels — they should match, allowing for any that failed to pollinate. See our corn season guide for when to buy fresh Australian corn.

What Happens to the Silk After Pollination

Once a silk strand has delivered pollen to its egg and fertilisation is complete, the silk has done its job. It dries up and turns brown. This is why fresh corn has pale, sticky, green-gold silks at the top — those are active and still capable of receiving pollen — while older corn has dry, brown, brittle silks that have completed their work. The colour of the silk is one of the freshness indicators you can check when buying corn.

After the silks dry, the kernels continue to develop and swell over the following weeks. The cob fills out, the kernels change from clear and watery to plump and milky (the "milk stage" when corn is sweetest), and eventually to starchy and firm if left to mature fully. Sweet corn is harvested at the milk stage for maximum sweetness. See our sweet corn guide for the science of why corn is sweetest the day it is picked.

Can You Eat Corn Silk?

Corn silk is technically edible, though most people discard it. It has a mild, slightly sweet, grassy flavour and is used in some traditional medicines, particularly as a tea for urinary tract health. There is limited modern research supporting these uses, but corn silk does contain compounds including flavonoids, volatile oils, and polysaccharides that may have mild diuretic and anti-inflammatory effects.

If you want to try corn silk tea, collect the fresh silks from sweet corn, rinse them, dry them, and steep a small handful in hot water for 5–10 minutes. The tea is mild and pleasant. Do not use silk from corn that has been sprayed with pesticides — buy organic or grow your own if you plan to consume the silk regularly. And if you have kidney issues or are on diuretic medication, talk to your doctor before trying corn silk tea, as its mild diuretic effect could interact with your medication.

What Causes Missing Kernels on an Ear of Corn

Missing kernels — gaps in the rows — are caused by failed pollination at those positions. The silk was there, but no pollen landed on it, or the pollen did not successfully travel down the silk. Common causes include:

• Heat waves during pollination. Corn pollen dies within minutes at temperatures above 35°C. A hot spell during the week of pollen shed can dramatically reduce pollination.
• Dry conditions. Silks need to be moist and sticky to catch pollen. Drought during silking makes silks dry and non-receptive.
• Poor wind. Corn is wind-pollinated, so still air during pollen shed means pollen does not travel far enough to reach all silks.
• Single-row planting. Corn pollinates best when planted in blocks rather than single rows, because pollen from neighbouring plants is more likely to reach all silks.

If you grow corn at home, planting in blocks of at least four rows and ensuring consistent watering during silking dramatically improves kernel set. See our regrowing guide for more on growing corn from scraps.

Corn Kernel Types and Silk Count

The number of silks and kernels varies by variety. Sweet corn typically has 400–600 kernels per ear. Popcorn has a similar count but smaller kernels. Flint corn and dent corn (used for cornmeal and stock feed) can have more. The arrangement is always in rows, and the number of rows is always even — a genetic trait of the corn plant. Each row has the same number of potential kernels, and each kernel has its own silk.

For a practical test, buy a fresh ear of corn and count the silks at the top. Then husk it and count the kernels. They should be roughly equal (some silks may have failed to pollinate). It is a nice demonstration of the one-silk-one-kernel principle and a good way to check the quality of the corn — well-pollinated ears have full, even rows with no gaps. Scan the corn with PickFresh to check freshness before buying.