Why is an ear of corn called an ear of corn? Well ...

First off, "ear of corn" has nothing to do with "ear of head". Of course, the "ear" in both looks and sounds the same, but they still have nothing to do with one another - just like an eel and a snake look the same, but are completely different. The German word for "ear" (of head) is "Ohr" (pronounced like the English "oar" used to row a boat), and it is no accident that "ear" (of head) and the German "Ohr" sound kind of similar, since they both share a common root.

"ear" in English, "Ohr" in German

The "ear" in "ear of corn", however, is scientifically called an "inflorescence" which simply means "a flowering", just like it does in all kinds of grasses and grains, like wheat, barley or whatever.

inflorescence ("a flowering") of wheat - or an "ear of wheat"

And, when we think about it, it's no surprise that when we grind up this "flowering", we get a powder called "flour" which basically just means "flower".

In Modern German, the inflorescence (or, as it's more commonly known: "sheath") is called an "Aehre" (pronounced: AIR-uh) which comes from an earlier form of the word: "Aeher". Already, we can recognize the similarity in spelling and sound that exists between that German word and our English "ear" of corn.

"corn" in English - "Mais" in German

What is called "corn" in English is also called "maize" which comes to us from the Spanish "maiz" (from "mahiz" - a word Columbus and his buddies learned in the Caribbean); the German word is also "Mais". In Germany, corn was primarily considered to be feed for animals. It was first in the 1970's that corn gained popularity with Germans as "human food". In German, an "ear of corn" is called a "Maizkolben."

The German word "Korn" means "grain" and is where we get our word "corn". So, an "ear of corn" comes (roughly) from an "Aehre von Korn"

"grain" in English - "Korn" in German

In this sense, our "corn" is like wheat on anabolic steroids.

(There is also a clear, vodka-like spirit (or "Schnaps") distilled from grain in Germany. This liquor is called "Korn", too!)

Finally, we should take a (somewhat scientific) look at where the word "Aehre" (and "ear") really comes from and which words are related to it:

The ancient (PIE) root *ak means "sharp, pointy" and even "stone" (from the sense of a pointy mountain top). "Aehre" and, so, "ear" developed from the prickly, pointy aspect of a sheath of grain. An example of other English words which contain the same ancient word root/concept are: edge, acid, acrid, acute, acerbate, acumen, acorn, and ax (btw, the Old Norse word for "sheath of grain" was "ax"). The latin word "acer" meaning "sharp, irritating, bitter", the greek word "acme" (pinnacle, zenith, summit) and the greek prefixes "acr, acro" (top, high, highest) also come from this root. Consider the word "acropolis" - the city on the top of the mountain. An example of German words deriving from *ak are: "Essig" (vinegar - because of the acidity) and "Ecke" (corner).