Seri use of the Agave (century plant or maguey) is described. Certain agaves, having a high sugar content, were a major source of food for the Seri. Food material prepared from agave was stored for future use. A method for obtaining an emergency supply of potable liquid was practiced. Seri nomenclature and usage of Agave seem to closely follow biosystematic classification. A rich Seri vocabulary is associated with the various agaves.