THE TYPE CONCEPT IN SYSTEMATIC BOTANY

Abstract

The binomial system of nomenclature has been an important factor in the development of taxonomy. The increase in the number of known species since the time of Linnaeus has been many fold; because of carelessness and ignorance the number of names applied to the species of plants has been much greater than the number of species; the increase in our knowledge of genetic relationships and the diversity of opinions among botanists concerning generic limitations have still further increased the synonymy. The confusion arising from these causes soon emphasized the need of a code of nomenclature by which the naming of plants might be regulated. Many codes have been proposed, but only two have received the support of international conferences: the Paris Code of I867, and the Vienna Code of I905. I have pointed out in another place (Science n. ser. 30: 597. I909) that absolute stability in nomenclature is unattainable so long as botany is a growing science. The limits of genera will vary according to the knowledge and the opinions of individual workers, and the names of the plants as they are assigned to this or that genus will change in a corresponding degree. A universal code cannot bring about a permanent nomenclature, but it enables botanists to apply names according to definite rules, and this is all that we may expect of any code. The two codes mentioned have been a great help in stabilizing nomenclature. Experience has shown, however, that they lack definiteness in directing the application of names, especially of generic names. In the early days of taxonomy a name was applied to a concept rather than to an entity. A generic name was based upon all the known species of the genus; a specific name was based upon all the known specimens of the species. When a genus was divided the original name was retained for one of the parts, usually the larger part, or was sometimes discarded altogether. The Vienna Code introduced many reforms, but the procedure for applying names when a genus or species was divided was still vague and uncertain in its application. About 30 years ago a new system began to receive serious attention among American botanists, the system of applying names by means of types. It is not my purpose here to give a history of this idea, but rather to point out some of the advantages of the system. The type concept lies