THE IMPORTANCE OF PLANTS 



William J. Robbins 



The Importance of Plants 



Reprinted with the permission of the author 

 and pubhshers from Science C: Nov. 17, 1944 

 and Ann. Kept. Smith. Instit. for 1945: 305- 

 312, 1946. 



Plants are the basis upon which all 

 other life depends. In the last analysis 

 they supply us with all the food we 

 eat, they maintain the oxygen content 

 of the air and they are the primary 

 source of those important accessory 

 foods, the vitamins. Without plants 

 we would starve to death, die of suf- 

 focation, and expire from a combina- 

 tion of deficiency diseases. In addition, 

 plants are the chief means by which 

 the energy of the sun is and has been 

 in ages past caught and stored for us 

 in usable form. Without plants fire 

 would be unknown because there 

 would be no wood or coal or petro- 

 leum to burn, and electricity— except 

 as a natural phenomenon — would be 

 at most limited to areas freely supplied 

 with water power. 



The essential relation of plants to 

 the food we eat, the air we breathe, 

 and the energy we dissipate with such 

 reckless abandon is based on two of 



their characteristics. These are their 

 ability to store the energy of the sun's 

 rays in sugar, starch, cellulose, oils, fats, 

 and other constituents of the plant 

 bodv, and their abilitv to construct 

 from simple and elementary sub- 

 stances types of chemical compounds 

 necessary for the existence of animals, 

 including ourselves. 



The first of these powers, limited 

 from a practical standpoint to plants 

 which possess the green pigment chlor- 

 oph}ll, is the familiar process of photo- 

 synthesis in which the plant transforms 

 water obtained from the soil and 

 gaseous carbon dioxide from the air 

 into sugar and oxygen. In the course 

 of photosynthesis, the first part of 

 which occurs only in the light, energ\' 

 from the sun is stored in the product 

 sugar and in the starch, wood, oils, and 

 fats, or other organic substances con- 

 structed bv living things from this 

 sugar. The encrg}' we obtain by burn- 



