First the history: Tequila was first distilled in the 1500-1600's in the state of Jalisco, Mexico. Guadalajara is the capital of Jalisco and the city of Tequila was established in about 1656. This is where the agave plant grows best.
The agave is not a cactus as rumored, but belongs to the lily family and has long spiny leaves (pincas). The specific plant that is used to make tequila is the Weber blue agave. It takes 8-12 years for the agave to reach maturity. During harvest, the leaves are cut off leaving the heart of the plant or pina which looks like a large pineapple when the jimadors are done. The harvested pina may weigh 200 pounds or more and is chopped into smaller pieces for cooking at the distillery.
Tequila was first imported into the United States in 1873 when the first load was transported to El Paso, Texas. In 1973 tequila sales in the US topped one million cases.
There are two basic types of tequila, 100% blue agave (cien por ciento de agave) tequila and mixto. The 100% blue agave tequilas are distilled entirely from the fermented juice of the agave. All 100% agave tequilas have to be distilled and bottled in Mexico. If the bottle does not say 100% blue agave, the tequila is mixto and may have been distilled from as little as 60% agave juice with other sugars.
Grades of tequila:
As the tequila is aged in wooden barrels, usually oak, it becomes smoother, with a woody taste and golden color. Aging may disguise the agave flavor and few tequilas are aged longer than three to four years.
Each distillery in Mexico is assigned a NOM number that shows which company made or bottled the tequila.
There is no worm in tequila, that is Mezcal which is a whole different animal.