54 THE STORY OF PLANT LIFE 



clature, includes the correct diagnosis of the characters 

 that distinguish a species, genus, or other grade of 

 affinity. It is customary to describe new species 

 to-day in Latin, as this language makes for concise- 

 ness and allows one a better chance of describing 

 minute differences than does English. The word 

 hairy, for instance, can be made capable of several 

 degrees of meaning in Latin, whereas in English it 

 is capable of but one without a qualifying adjective. 



Descriptions must be framed upon a proper system. 

 The parts described should be taken in the natural 

 order, starting from the earliest or lowest organs, and 

 proceeding upwards. There is a special terminology 

 or system of description for each of the parts of the 

 main different systems of organs, such as root, stem, 

 leaves, flowers, fruit, or seed, and the terminology of 

 the one will not as a rule suit that of the others. 



The form of the description also requires careful 

 study, punctuation in particular demanding special 

 attention, as upon this depends the separation of the 

 description into its proper parts depending upon the 

 morphological sequence. 



17. Evolution. 



The types of plants considered on a basis ot 

 structure and form are not all of the same degree of 

 development. There are lower types and higher 

 types. It is natural to suppose that the latter have 

 been derived from the former. It is not, however, 



