What is a tassel?
Simply put, the tassel is the top most part of a corn plant. Here is a picture that shows a corn plant with the tassel fully opened or out.
The corn tassel is the part of the plant where the pollen comes from. The pollen pollinates the ear of corn, which causes the ear of corn to grow. Pollination occurs when pollen falls off the tassel and then blows through the wind and eventually comes in contact with the silk on the top of the ear of corn. Ears of corn start growing silk at the beginning of the R stages. When the silks dry and turn brown, the pollination process is done and the ear of corn will continue to grow.
What is detasseling?
You may have heard of high schoolers having the summer job of detasseling - so what exactly is it? Seed companies hire detasselers to help them create specific cross pollination of corn plants. The work done by detasselers will eventually result in new corn hybrids that farmers will want to plant. To produce this specific cross pollination, seed companies designate male and female rows of corn. All female rows have their tassels pulled by hand. Male rows are left alone so their pollen in their tassels will cross pollinate in the neighboring female rows. Cross pollinating is when you have pollen from one variety of corn fertilize or pollinate the silk of another and different variety of corn.
So now when somebody is talking about corn tasseling or you see those "yellow tops" on the corn, you'll know what tassels are and the importance of this corn growth stage!