Huh, that can't be right?
New collectors of ancient coins from the U.S. are often surprised to see ancient Greek and Roman coin descriptions that indicate corn is depicted. Yes, "corn" as it is used in American English is a New World crop and can't be depicted on ancient coins. However, in most of the world, what is called "corn" in the U.S. is called maize. Outside the U.S., corn is a more generic term for grain. At Forum Ancient Coins we use grain instead of corn (mostly to save us the trouble of answering emails explaining to us that our coin description must be wrong).
In German, corn means rye. In 1946, when famine struck post-war Germany, the Americans asked what they could do to help and received the answer, "Send corn." Germany was flooded with American corn, maize of course, a grain almost unknown by the German people at that time.
Der Kleine Pauly: Lexikon der Antike in funf Banden discusses ancient grain types as follows:
1. Hordeum, barley, was planted in Greece from the earliest times because it grew better in this region than the early wheat. In Attica, in the 4th Century B.C., ten times much barley was grown than wheat. Then over time it was replaced by nude-wheat, which has more protein. Today in Attika the crop is only one third barley and two third wheat! Today barley is mostly grown for animal feed.
2. Triticum, wheat, was the main grain in Italy. There were two variants, nude-wheat and spelt (with long hairs). Nude-wheat slowly replaced spelt, especially after the hexaploid form of wheat was cultivated. In the Imperial times this form, called siligo in Latin, was the main grain for bread. Frumentum, a common Latin term for wheat, also referred to this hexaploid nude-wheat. The "corn-ears" commonly seen on coins hanging out of a modius are probably this grain.
3. Sicale, rye, was grown north of the Alps where the weather was too cold and wet for growing wheat.