A grape was a type of fruit which can be used as a food or developed into a beverage. A common beverage made from grapes is wine and champagne. Grapes can be colored green, purple, black, yellow, dark blue, orange and pink.
The highlands of Areta had good soil and weather that led to the cultivation of grapes. These grapes could then be developed into a rich and full-bodied wine that the mutants would use for trade with other cultures. (TOS novel: Vulcan's Glory)
In the year 2268 while Captain Kirk was on Direidi he was informed that he could have grapes, but they would not be fed to him while on a couch. Grapes were widely grown in Direidi. (TOS novel: How Much for Just the Planet?)
The surface of Sherman's Planet did not take many Terran plants however the grape plants were able to thrive and combine with the native flora after a few years. This combination created a few variety of wines. (SCE eBook: Oaths)