There is a lot to do about the naming of Thymus species. Here is a list with synonyms. The first is the synonym, the 2nd the 'real' names.
Here is Thymus serpyllum an accepted name and the Thymus praecox subsp. arcticus is renamed as T. polytrichus subsp. britannicus.
http://www.users.waitrose.com/...
http://www.users.waitrose.com/...
So confusing.
Is your information from a more recent date?
