It was also called maize, especially varieties which did not appear or taste like the most common yellow eared cultivar. Confusingly, the term was also used in ancient Great Britain on Old Earth to mean any grain, including wheat, oats, etc.
Corn was a food plant originally developed (widely regarded as an outstanding feat of botanical engineering) from an unpromising grass by humans in Mesoamerica. As late as the beginnings of the Space Age on Earth, a great many different clutivars remained in cultivation in that area. It was an exceptionally productive plant and became a central part of pre-Columbian agriculture and civilization. After the discovery of the New World, the plant and its cultivation was spread throughout the planet.
- Detailed article about corn on Wikipedia