260 BOTANY: PRINCIPLES AND PROBLEMS 



These units of classification which we have ilkistrated include 

 the most important ones, but large groups are often subdivided 

 still further for purposes of convenience, so that we meet with the 

 terms variety, tribe, section, sub-family and others, each of which 

 has its assigned place in the system. Every one of the thousands 

 of groups in the plant kingdom has its own peculiar and distinctive 

 characteristics in which it differs from every other group of similar 

 grade, so that a botanist is able to place a newly discovered 

 species in just the particular niche which it should occupy with 

 reference to the plant kingdom as a whole. 



Nomenclature. — The technical names for these various groups 

 are derived from the Latin and Greek tongues, and although 

 many plants have ' ' common ' ' names in the language of the country 

 where they grow, the advantages of technical or "scientific" 

 names are so great that they are almost exclusively used 

 by botanists. 



In earlier days, before our present system of naming plants 

 had been introduced, the common way in which a botanist 

 referred to a given species was to use a cumbrous descriptive 

 phrase, usually consisting of several Latin nouns and adjectives. 

 As different men often used different words, it frequently became 

 a matter of doubt as to just what plant they were talking about, 

 and much confusion resulted. It remained for the genius of 

 the great Swedish naturalist, Linnaeus, to devise a method 

 which should be simple and uniform. He invented the Binomial 

 system of nomenclature, so called because each species is given two 

 names; first, the name of genus of which it is a member, or its 

 generic name, and following this a name applied distinctively to 

 the particular species in question, or its specific name. The 

 scientific name of the Dog Rose would thus be Rosa canina. 

 This system is very much like that used by us in naming individ- 

 uals, where the "surname" is that of a person's family and the 

 "given name" is distinctively his own. In plants, this order is 

 simply reversed, the surname (generic name) coming first. The 

 binomial system was first used extensively for plants in the 

 "Species Plantarum", a great work published by Linnaeus in 

 1753, in which he described all plant species then known. This 

 book is the foundation upon which our modern system of plant 

 nomenclature is based. 



In order to avoid confusion and to make perfectly clear what 

 plant is meant, there is placed after the plant name the name 



