Chem #91 is thought to be an offshoot of the original Chemdog strain, and the numerical addition of “91” is believed to reference the year the strain first came into existence. Some growers believe Chem 91 to be a cross between Chemdog and Skunk, which may explain its particularly pungent aroma. In true family spirit, this hybrid has a very strong diesel smell with a piney-lemon aftertaste