By definition, no. Cannabis is the genus and encompases 3 species: C. sativa, C. indica (with a subspecies C. indica afghani that is still being argued over), and C. ruderalis.
If we want to get general and say that C. ruderalis isn't pot (it's not a drug-grade cannabis species), then yes, you can breed it. That's where LowRyder came from. C. ruderalis has the interesting trait of flowering based on calendar age, rather than season.

If you bump up one rung on the classification ladder, you find the other living member of the family cannabacea, which is Humulus lupulus, the noble beer-hop. Cannabis can be GRAFTED onto hops, but I don't believe that they have ever been reproduced sexually.

Hope that helps.