From: "Using Hops" by Mark Garetz, (with his expressed permission), pages 26-27, section title 'Decoding European Hop Names'.
As was mentioned earlier, European (mainly German) hops usually have the growing region as part of the hop's name. The primary reason for this is that most of the important European varieties only produce the desired brewing qualities when grown in a specific region. Through many years of natural selection, varieties that are indigenous to the growing area have emerged, mainly because only one varity was grown there, so there was no need to be more specific. Some of these varieties are still grown in their place of origin and some are not.
European hops may have the same variety name as the place where they originated. But because these hops may no longer be grown in the place after which they are named, the place where they are now being grown is attached to the hop name as an adjective. Here's an example: A common hop from Germany is the variety called Hersbrucker. It originated in the Hersbruck region. It is called a Hersbrucker because it came from Hersbruck. Think about it this way: If you came from New York, we could call you a New Yorker. The "er" is always part of the *variety* name. If this hop was grown in the Hersbruck region, this hop would be called a Hersbruck Hersbrucker. But most of the Hersbrucker grown today is actually grown in the Hallertau region. Hersbrucker grown in the Hallertau region would be called Hallertau Hersbrucker.
This gets confusing because there is also a Hallertauer variety. When it is grown in the Hallertau, it is called Hallertau Hallertauer. Now I'm going to throw one more curve at you: The most prized hop in the world is the noble hop Hallertauer Mittelfruh. "Now wait a minute!" I hear you say, "I thought I was just getting this straight, and here's a hop name with an "er" on the *first* word." Well right you are, it doesn't appear to be 'correct'. Well that's because the real name for this hop is Hallertau Hallertauer Mittelfruh. Mittelfruh means "middle-early" in the growing season. Hallertauers that matured at different times just weren't the same. So "Hallertauer Mittelfruh" is a sub-variety of Hallertauer. To shorten the name up, most people leave off the first Hallertau since all Hallertauer Mittelfruh was assumed to be grown in the Hallertau.
Let's recap how German hop names are put together: The *first* word is the place where this actual hop is grown. It does *not* have an "er" on it. The *second* word is the variety name. If the variety was named after a place, it has "er" tacked on the end. Sometimes there is a third word that can describe a sub-variety, in which case the first word (where its now grown) is sometimes dropped. Examples are Hallertauer Mittelfruh and Hallertauer Tradition.
Now if someone is selling something they simply call "Hallertau" your first question should be "Hallertau what?" Usually this will be Hallertauer grown here in the US. Don't assume that just because the word Hallertau is used that the hop was grown in Germany. And if it is from Germany, you now know that "Hallertau" only tells you *where* the hop was grown, not which *variety* (lots of different varieties are grown in the Hallertau). We'll get more into depth on this subject in the chapter on buying hops.
That is the basis for my understanding of how to 'decode' a (German) hop name.
Many thanks to Mark for allowing me to blatantly copy from his excellent book.
Boom, like that.