FUNDAMENTAL NOTIONS 5 
9. Plant Geography. The study of the present dis- 
tribution of plants over the earth's surface, and of the 
causes and consequences of this distribution, is plant 
geography (sometimes called phytogeography}. 
10. Fossil Botany. The oldest known rocks contain 
the remains of plants that lived thousands probably 
millions of years ago. These remains often, though not 
always, of stone, are fossils, and their study constitutes 
the study of fossil botany, or paleobotany. This study 
is not only interesting in itself, throwing much light 
upon our knowledge of plants, but is also of great value 
to the geologist, often helping him to interpret correctly 
the rock -layer, and to decide to what geological age it 
belongs. By means of fossils, we may also learn much 
of the climate of past ages, and the great changes that 
have since taken place. Thus, when we find fossil re- 
mains of tropical plants, such as palms, in the rocks of 
the present arctic regions, we know that there must have 
been a tropical climate in that latitude at the time the 
plants, now fossils, were living and growing there. 
11. Educational Value of Botany. From the preced- 
ing paragraphs it is evident that a study of plants will not 
only give us valuable information that may be used to 
advantage in every day life, but that it will give us a 
broader outlook than we might otherwise obtain over the 
past and present of the world in which we live; it may 
not only suggest to us the vocation we would prefer to 
follow, but may give us a breadth of view and a wealth 
of ideas that will help to increase both our usefulness and 
happiness. 
12. Plan of Study. We shall first review the structure of 
a familiar type of plant, and then make an elementary study 
