CHAPTER XV E 
‘THE CLASSIFICATION AND NAMING OF PLANTS ; 
The classification and naming of plants belongs to that depart- 
ment of Botany called Taxonomy, a name which was derived 
from two Greek words, taxts, arrangement, and nomos, law. 
PRINCIPLES OF CLASSIFICATION 
The modern classification of plants is an attempt to arrange 
plants in groups based upon their natural relationship or genetic 
affinities. The basis of all modern classification alike of plants 
and animals is the theory of organic evolution. 
Organic evolution presumes that all organisms living to-day 
have descended from preexisting organisms either by direct 
descent or by common. ancestry. Sufficient evidence has been 
brought forth during the past century to substantiate plant 
evolution. The sources of this evidence have been found in part 
through the study of comparative embryology, anatomy and 
histology of plants, the study of fossil plants found in the rocks of 
past ages of the world’s history in comparison with living forms of 
the present age, the comparison of life histories of present day 
plants, and through the more recent sero-diagnostic tests of Carl 
Mez and his pupils. 7 
A system of classification based upon natural resemblances of 
plants related by descent is called a NATURAL System. Any 
system of classification which does not take into account the 
natural kinships and evolutionary tendencies existing between 
plants is called an ARTIFICIAL SYSTEM. © 
A number of artificial systems were derived and used by 
botanists of the past. Most of them were based upon some 
arbitrarily chosen character such as woody stems, petals, 
stamens, etc. 
Theophrastus (370-285 B.C.), a pupil of Aristotle, and prob- 
ably the earliest of pioneers in attempting a scientific grouping of 
plants, classified them structurally into trees, shrubs, undershrubs, 
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