402 VARIOUS PLANT GROUPS 
and subdivisions of the vegetable kingdom, together with 
one hundred of the more important families of seedworts, 
and the orders and higher groups to which they belong. The 
characters given to distinguish them must be understood 
as being merely those which prevail throughout the group 
to which they refer, and not as being without possible excep- 
tions besides those noted. The numbers in parenthesis refer 
to pages where further information regarding the families, 
or illustrated examples of them, may be found. These 
synopses show the place in a modern classification of every 
plant we have studied in the foregoing chapters. Familiarity 
with the distinctions given, obtained by practical use of the 
synopses, should enable students to tell at sight, for a large 
majority of the plants they may see growing wild or in culti- 
vation, the family to which each belongs. 
The student who has learned to know what is typical of 
the comparatively few orders and families which we have 
been examining, will be able to tell at sight the family or 
order in which, or near which, to classify more than half of 
the flowering plants he is likely to meet; provided, of course, 
he has observed carefully their structural features. This 
knowledge, and the acquaintance he has already gained with 
the most important descriptive terms, will facilitate his use — 
of systematic works in which these and other families are 
described in more detail. 
However far he pursues this line of studv—as fascinating 
as it is exhaustless—the student will continually encounter 
plants which must be viewed as intermediate links connecting 
different groups, or as exceptions which make definite limi- 
tations practically impossible. These connecting links and 
exceptional cases seem to defy classification in any consistent 
arrangement, and have caused endless trouble to botanists 
in their attempts to construct a natural system. But at 
the same time it has happened that as botanists have come 
to study the significance of these exceptions they have found 
them revealing some very deep truths which have led to 
more and more satisfactory svstems of classification. It 
behooves us therefore to examine the main beliefs which 
have been held in regard to the meaning of these connecting 
