This year much of the field corn in southern Minnesota had grown to 5 to 6 feet by July 4th. Now many of the fields are pollinating, so we see the tassels and silks. It's also time for the first locally grown sweet corn to go on sale.

In Minnesota, corn is an annual, usually planted in May. Various varieties of sweet corn are harvested from July into September, with the main harvest time for field corn varieties stretching from late September through November.

Corn is the No. 1 agricultural crop in volume and value in the United States. Minnesota is fourth in the nation in corn production, following Iowa, Illinois and Nebraska.

An average ear of corn typically has 800 kernels in 16 rows. That is pretty amazing when you think of one seed being turned into 800. Just think of the many uses and countless products coming from corn, including plastics, ethanol, cooking oil, corn syrup and popcorn. But also ponder the pollination biology that makes it possible. The male tassels on top of the plants function to produce ample quantities of pollen to fertilize the female structures, the "ears." The silks catch pollen and send their nuclei to the corn ear. So each silk is a long slender tube attached to the potential kernel on the ear. A pollen grain's nucleus must move down each tube to fertilize the egg and begin developing a kernel. There is one silk for each kernel of corn on a cob. It's a mind-boggling process.

Jim Gilbert's Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. He taught and worked as a naturalist for 50 years.