In the Mediterranean( and parts of Europe beyond), corn was the generic term for cereals that grew there. Those most produced and most consumed, of course- varieties of wheat and barley, not the maize ubiquitous in Mexico!! These bearers of the name corn, and olives and wine, were the three major agricultural produces in the Mediterranean.
Olives grew in groves or orchards, grapes -the source of wine- in vineyards, and corn in fields.....and so they do now.
Olives hung from branches of living wood, grapes from spineless plants( so tall they required manufactured support. Several grapevines could traverse a single wall.....and still can, I guess; but individual climbs around wood sticks or metal rods are the visible norm. Moving our eye further through the present, we can confidently say that corn has always perched on stalks of grass, and olives have always hung from trees.