Colorado growers P Bud & Joe Brand were growing a strain they alternately called the "Dog bud" (because it was said to make the smoker roll on the ground like a dog), and the "Chem" weed (because of its unique almost chemcial funk). After turning on an East Coaster to the strain on Grateful Dead tour, they stayed in touch, and later sent some herb East to their friend. In one batch, the recipient found seeds, which would later be known as the Chem line (Chemdog [aka Chem 91], Chem B [aka SistaChem], Chem D, and Chem 4).
Most research shows a large fog cloud surrounding all true origins, but once you've smelled ChemDog you know it's a building block in much of what you pick up today.
Very light coloration from trichome count. A great middle road density.
Sour, chemical pine, sweet, soil.
Similar flavor to Sour Diesel strains as this is a major component of that strain - sour, soil, floral, and the famous chemical/fabricated Pine Fresh scent.
Fast acting, the sativa dominant traits lead to a clear, head-based effect. The medicine delivers itself quickly, but also climbs for a little while before going full-force. This is a talkative medicine, but with enough indica to not acquire the racey edge.