It has been asserted that there are legal species of marihuana plants, and this contention has generated frequent court challenges of criminal prosecutions involving marihuana. Invariably the claim is made that the name C. sativa used in legislation is insufficiently comprehensive to proscribe all forms of marihuana. The maneuver being used, alarmingly, is potentially applicable to innumerable other materials, but its success is based on a failure to appreciate the subjective nature of taxonomy and the little-known but critical ambiguities which are inherent in scientific names. The complex principles and operational conventions of biological nomenclature are presented in elementary fashion. Despite important technical constraints on the use of scientific names, some facts are clear: these names are used subjectively, they may be highly ambiguous, the consensus on use of these names is liable to change with time and, most important, quite permissibly they may have substantially different meanings to different users. The claim that there are legal species of Cannabis merely amounts to a semantic ploy in which certain of the variants of Cannabis that have customarily been understood to be denoted by the species name C. sativa, and which are clearly understood to be proscribed, are simply arbitrarily redefined as different species. This ploy has proven unsuccessful in all cases where scientific evidence was adequately presented by the state and in all important court cases where the issue was critically examined.