The following is from Jeff Burbrink, Elkhart County Extension educator.
Tassels began to emerge in some area corn fields last week, signaling the start of the reproduction phase of corn's development.
Corn is one of a number of plants that have both male and female flowers on the same plant. The tassel, which produces pollen, is the male flower, while the ear and the accompanying silks is the female portion of the plant.
The term monoecious is used to describe plants possessing both sexes, and includes other familiar plants such as pine, oak, melons and tomato.
According to Bob Nielsen, Purdue Extension corn specialist, there are about 1,000 spikelets on each tassel. Each spikelet bears two florets, and each floret has three anthers, the pollen producing portion of the plant. That means there are about 6,000 pollen-producing structures on a single tassel.
Pollen is shed starting at the middle of the tassel, and progresses upward and downward from there. An individual tassel might shed from 2 to 25 million grains of pollen over the course of about a week.
The pollen grain itself contains the male genetics needed to pollenate the ear. The outer membrane on the pollen grain is very thin and is viable for only a few minutes before they dry out. Nielsen says in a 15-mile-per-hour wind, the pollen grain might travel about one-half mile before it dries out.
One of the concerns we have heard in recent years is that pollen from transgenic plants might drift out of a field and cause genetic contamination in neighboring fields. Nielsen said that recent research has shown that the overwhelming amount of pollen stays in the field where it is produced.
Weather plays a big role in the health of the pollen. Extreme heat (above 100 degrees F) can kill pollen, but the plant has developed protective behaviors to reduce this issue. Pollen matures over several days and this reduces the risk of extreme heat ruining pollination. Another strategy that corn uses to avoid pollen death is that most of the pollen is released in the morning hours, when the air temperature is generally cooler.
Tassels have also been a source of income for hundreds of people each year. Hybrid seed corn seed is the product of crossing a male of known characteristics with a female corn plant of known characteristics. To cause the male and female to mate, the tassel is removed from the plant that is going to serve as the ear-growing female. The male tassel bearing plant is allowed to release its pollen. Since the male pollenates itself, the male row is then destroyed, leaving the tassel-less female plant with an ear of next years seed.
Next time you look at a corn tassel, I bet you will look at it a bit differently.