What is the word to describe a single object to represent the many?

If I am writing a poem, I might use the word peaches to symbolize all fruit. Is there a specific word for this type of symbolism?

Solution 1:

It's called metonymy. For example, sword for "war" or Washington for "the US Government".

Cf. http://en.wikipedia.org/wiki/Metonym

Solution 2:

If you're interested in a suitable word outside the realm of literary criticism, you might consider exemplar especially if you're looking for the connotation of the single best representation of the many.

Wiktionary gives the definition of:

Something typical or representative of a class

Something fit to be imitated