Thursday, March 1, 2012

Taxonomy of Agaves and Vino-mezcal

The variegated American agave.
The agave -- known for its beauty, its longevity, its danger and its power to intoxicate -- is about to lose its name.  Taxonomists have a propensity for reclassifying and renaming plants, and with the development of molecular techniques (“DNA”) reclassification has become rampant.  But this is not the work of an ordinary academic taxonomist.  It is the Mexican government, under pressure from the distilled spirits industry, that wants to reclassify “agave” to include just six of the ca. 200 species now recognized.

Agave americana 'Marginata'

The Plants

Agaves (aka century plants or maguey) are native to the New World, growing as far north as southwest Utah, southern Nevada and southeast California, and as far south as tropical South America.  The greatest diversity is in Mexico.  It was the Swedish botanist Linnaeus who came up with the name “agave” -- for a plant brought back to Europe from the New World in the 16th century.  Agave americana was included in Linnaeus’s 1753 Species Plantarum, considered the first list of validly published plant names.  Today the American century plant is grown around the world as an ornamental, and many varieties have been developed for landscaping.

The Utah agave grows as far north as southern Utah
and Nevada.  Closeup of leaves in next photo.  Courtesy
Agaves live much of their lives as rosettes of basal leaves, usually succulent, sometimes quite large, and occasionally quite dangerous.  The leaves are spine-tipped, often with spines along the margins as well.  The leaf-tips of the lechuguilla (below) are surgically-sharp, capable of penetrating clothing, leather and even tires on occasion.  They are a hazard for humans, wildlife and livestock.  Because of their spiny-ness, agaves sometimes are mistakenly called cacti, but the two groups are not related.  Agaves are monocots -- like the lilies, orchids and grasses.  Cacti are dicots, part of the other major branch of flowering plants.
Agave lechuguilla.  The common name is shin dagger or simply lechuguilla.
Photo by Patrick J. Alexander @ USDA-NRCS PLANTS.

An agave plant may persist as a rosette for 30 or 40 years, accumulating carbohydrates all the while.  Then it blooms, producing a flower stalk as much as 20 feet tall topped by a large inflorescence (cluster of flowers). The individual rosettes usually are monocarpic, meaning they flower once and then die, but the actual plant lives on.  Many agaves are rhizomatous, and neighboring rosettes may be connected underground. Sucker shoots frequently grow from bases of dead flower stalks, developing into “pups” (young rosettes).

Left, the desert agave (A. desertii) in bloom.  Photo by Stan Shebs.

Flowers of Agave gigantensis.  This species was named not for its size, but for where it was
first collected, in the Sierra de la Giganta (Mountains of the Giantess) in Baja California.
© 2006 Mark A. Dimmitt / ASDM Sonoran Desert Digital Library
Collecting and preparing an agave specimen for the herbarium is an art.
Agave gigantensis from the Arizona State University Herbarium.  Click to view.

Species of agave can be difficult to tell apart, especially in areas with long histories of  utilization and cultivation.  Native Americans used agave plants for food and fiber, and developed many varieties through selection and hybridization.  The agaves currently used for fiber are hybrids of unknown origins.  Most commercially-produced sisal (fiber) comes from Agave sisalana (photo to left), but sisal is produced locally in Latin American from henequen (A. fourcroydes) (Reveal and Hodgson).

The Beverages

Alcoholic beverages made from agaves have a long tradition in the New World.  Pulque or octli is a milky-colored drink made from yeast-fermented agave sap, indigenous to central Mexico (photo on right).  Originally it was drunk only by the elite, but became a beverage of the masses following the Spanish conquest.  Pulque's popularity declined in the 20th century, giving way to beer, but now appears to be on the rise due to promotion by the tourist industry.  I remember drinking sweet tangy pulque in the 1970s while riding trains through northern Mexico -- sold by young boys, quality unknown, mildly intoxicating.

Aguamiel -- honey water -- is the non-alcoholic version of pulque.  This is straight agave sap, believed to have therapeutic value.  The video below is about collecting and drinking aguamiel.  Note the impressive size of the agave or maguey, and its wicked leaf margins (the spines are removed prior to harvesting sap).  The reference to “nectar” in the video technically is incorrect.  Nectar comes from flowers; aquamiel is made from the sap of the stem or “heart”.

Pulque is the most common of the fermented beverages made from agave, collectively referred to as mezcal.  When the alcohol is then distilled (concentrated) after fermentation, the result is vino-mezcal.  Tequila is the best known of the vino-mezcals.

Tequila is legally produced within a five-state region in central Mexico.  For liquor to be called “tequila”, at least 51% of the plant material has to be Weber blue agave, Agave tequiliana ‘Weber’.  The more expensive tequilas are made entirely with Weber blue agave,"100% agave azul", and all the sugar is agave sugar.  In mixto tequila (labeled simply “tequila”), as much as 49% of the sugar can be from other sources, commonly sugar cane.
Cultivated Weber blue agaves.  Photo from TequilaSource.

Weber blue agaves are grown from hijuelos -- young shoots removed from mature agaves.  The hijuelos grow into rosettes that weigh as much as 75 kg (165 lbs) when harvested.  In harvesting, leaves are removed from the agave hearts, also called heads or piñas (pineapples).

Photos left and below from TequilaSource.

The hearts are slowly cooked to tenderize plant tissues for shredding; juice is then extracted for fermentation.  After fermentation, the liquid is twice-distilled to bring the alcohol level to 55%, and subsequently diluted with de-ionized water to 35-43%.  The Tequila Process is explained in detail, with videos, here.

Mezcal, famous for the worm in the bottle, is another popular vino-mezcal (not to be confused with fermented agave beverages as whole, also called mezcal as explained above).  Mezcal can be made from from several types of agave as long as it is comes from the proper region, the Oaxaca area.  Bacarona, also branded, is made in Sonora from Agave angustifolia roasted over a mesquite fire.

Tequila producers in Mexico already have branded “tequila”, “mezcal” and “bacanora”.  Now the Mexican Institute of Industrial Property (IMPI) has proposed branding “agave” for the exclusive use of producers in those areas where tequila, mezcal and bacanora are made.  A second proposal, NOM-186, specifies that distilled products labeled "agave" can be produced from only six species of agave, even though plant systematists currently recognize on the order of 200 species, at least 39 of which are used in making vino-mezcal.  Other agave-based spirits would be labeled  “agavacea”, a misspelling of Agavaceae, the agave family.

Not surprisingly these proposals have raised public outcry, from biologists and bartenders as well as consumers and smaller producers of vino-mezcal.
“According to Suro-Piñero and various bartenders moving the information and call for signatures through Facebook and Twitter, the legislation would have the most impact on small producers of mezcal, a category increasing in popularity in the U.S.  ‘This legislation is deliberately designed to eliminate artisanal, traditional small producers,’ argues Suro-Piñero. ‘It's similar to legal pressure that was created against microbreweries. It makes it tough to grow consumer interest.’”
An online petition has been posted by the Tequila Interchange Project, “dedicated to promoting awareness about the culture of tequila for industry professionals in USA and Mexico” and advocating for “the preservation of sustainable, traditional, and quality practices in the tequila industry.”  For a thorough discussion of the negative impacts of the proposed regulations on small agave growers and producers of artisanal mezcals, see “NOM-186:  NEWS REPORT” from CLASS magazine.

These efforts apparently are having an effect.  The Mexican government now is reviewing the proposed regulations, and looking at ways to “reformulate” them.
Mayahuel, Aztec goddess of pulque.

1 comment:

  1. Agavacea is not an error but the old Spanish version of the family name. I know botanical names are supposed to be a universal language but the Spanish-speakers did not get the memo. I was caught out a few times looking up Chenopodiaceae which is known as Quenopodiaceae.