Similar to indigenous people centuries ago in Mexico and Central America, corn growers continue to cultivate numerous varieties.

Modern corn, or maize, actually is a tall, annual grass. All kinds, including ornamental corn, popcorn, field corn and sweet corn, are varieties of a single plant called Zea mays. About 350 types of corn are grown in Peru.

Corn is the No. 1 crop in the United States in volume and value. 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's pretty amazing when you think of one seed being turned into 800, and sometimes more than one ear is produced on a single plant.

Sweet corn is also known as sugar corn. Its botanical name is Zea mays variety rugosa. Nothing tastes like an ear of corn cooked as soon as it is picked. Sweet corn with yellow kernels is a favorite, but white kernels are preferred in parts of the United States.

There are now ultra sweet and super-sweet hybrids, as well as bicolor hybrids with one super-sweet parent that are bred for enhanced sugar. The sugar in these sweeter hybrids does not convert to starch as rapidly as in standard hybrids.

Jim Gilbert's Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. His observations have been part of the Minnesota Weatherguide Environment Calendars since 1977, and he is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.