THE NATURE OF SEEDS 337 



advantage to plants in nature as a means of reproduction ; 

 they are also a great advantage to man as a means of agri- 

 culture. They are absolutely necessary to it. Without 

 seeds, the cultivation of plants as it is to-day would come 

 to a full stop. Without seeds the hfe of all animals would 

 be imperiled, and most of the plants which we see to-day 

 would disappear. Seeds thus form a necessary link in the 

 chain of Hfe. Food, whose manufacture began in the leaves, 

 comes to be stored in them. To us they are more than 

 the harvest of this season. They are the assurance of 

 harvest in the seasons which are yet to come. 



B. The Importance of Seeds to Plants. — Many flowering 

 plants reproduce their kind abundantly by means of struc- 

 tures other than seeds. You have noted that horizontal 

 stems are especially efficient in this direction. (See page 

 157.) Reproduction of this kind is especially characteristic 

 of the grass family. Bulbs are especially characteristic of 

 the lily family. Duckweed and bamboo are successful 

 plants which may go for many years without producing 

 flowers, while marly cultivated plants are propagated 

 successfully without the aid of seeds. 



Most flowering plants, however, depend mainly or ex- 

 clusively upon seeds for their perpetuation. Consider that 

 extremely large class of plants which are annual, those 

 which die down at the approach of winter. Throughout 

 the world, wherever winter comes, these plants cease to 

 exist for several months except as seeds. Yet, when 

 spring comes again, they grow up by the milUon, convinc- 

 ing evidence of the abihty of their seeds to protect the 

 tender embryos within them. Many of our most common 

 weeds are plants of this character. 



