4 INTRODUCTION 



Plants are partners in life with us. They lived in the 

 world before men lived in it, and they made the world 

 habitable for men. The laws of life which control them are 

 the laws of life which control us. To understand our own 

 lives we must understand their lives. To understand their 

 lives is to improve our own. 



2. Our Enjoyment of Plants. — We enjoy the country 

 chiefly because of the plants which cover it. We enjoy 

 spring chiefly because then the grass turns green, flowers 

 begin to bloom, leaves come out on the trees, and young 

 plants grow up in the gardens. We may find it hard to 

 explain this pleasure that we get from plants, but we feel 

 it none the less. Something in us seems to respond to 

 them. In fine weather we are glad to get out of the city, 

 to go for a holiday into the country, to lie on the grass in 

 the shade of trees, to look at what is green and growing. 



The surface of the land is hidden by plants. They form 

 the natural covering of the soil. Suppose you were up in 

 an airship on a summer day. Green would be the color 

 of the earth beneath you, the green of plants. The roads 

 would make a few white lines across the green, and here 

 and there you would see a house or catch a glimpse of a town. 

 But nearly everywhere the earth's surface would be green, 

 — green with the millions of plants which grow upon it. 

 Of animal life hardly any evidence at all would be visible. 



Suppose it was a July day and you were looking down upon 

 farm lands in the Mississippi Valley. Corn fields would be 

 below you, miles on miles of them, deep green and growing, 

 shining in the sun. Here and there you would see fields of 

 wheat and oats, pale green or turning yellow, through with 

 their growth and ready for the harvest. In some fields you 



