INTRODUCTION 
what is apparently their genetic affinity, or actual relationship to one another 
by descent. In this study of classification it is found best to consider 
almost exclusively the evidence derived from the anatomy or structure of 
the plants. Groupings dependent upon physiology or function, such as 
plants that climb, plants that live as parasites, plants which form large 
trees, or plants which live in water, are found to afford no clue to 
community of origin. At the same time, though our main attention must 
be devoted to structure, physiological matters are of such great interest 
that they will often be referred to in our notes. Structure, in fact, is of 
little interest apart from its functions ; the mechanism apart from its 
application when in action. 
While the parts of a plant considered with reference to their functions 
are termed organs , it is possible also to refer them to a small number of 
_ „ structural types or plans of construction which are known 
The Parts : t r 
as members. Almost all the structures of Flowering Plants 
of Plants . ° 
can be considered as roots , shoots , stems , leaves , or hairs , whilst 
these primitive members are spoken of as being variously modified , 
according to the functions they have to perform. These functions fall, in 
the case of plants, almost entirely into two great classes, vegetative and 
reproductive , according as they subserve mainly the nutrition, growth, and 
development of the individual, or the production of seed for the perpetua- 
tion of the species. Roots, stems, and most ordinary shoots and leaves 
are vegetative organs; while specially modified shoots, known as fiowers , 
and special parts of such shoots forming fruits, subserve mainly the 
production of seed and are, therefore, reproductive organs. 
The chief characters of Flowering Plants, by which they are 
distinguished from lower types of existing plant life, are these more or 
less conspicuous fiowers, and the seed to which they eventually give 
rise, and for these reasons Flowering Plants are technically known as 
Phanerogamia (from the Greek (fravepos, phaneros, conspicuous ; yapos , gamos, 
marriage) or as Spermatophyta (from the Greek cnreppa, sperma, a seed ; 
(jivTa, phuta, plants), as distinguished from the Cryptogamia (Greek tpvmbsy 
kruptos , hidden) or Flowerless Plants. 
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