194 



ESSENTIALS OF BOTANY 



successful tumbleweed, a plant must be pretty nearly 

 globular in form when fully grown and dried, must be 

 tough and light, must break off near the ground, and 

 drop its seeds only a few at a time as it travels. A 

 single plant of Russian thistle is sometimes as much as 

 three feet high and six feet in diameter and carries not 

 less than two hundred thousand seeds. 



239. Many-Seeded Pods with Small Openings — There 

 are many fruits which act somewhat like pepper-boxes. 



Fig. 146. Three Fruits adapted for Dispersal by the Shaking 

 Action of the Wind. 



I, celandine; II, pea; III, jimson weed {Datura). 



The capsule of the poppy is a good instance of this kind, 

 and the fruit of the lily, monkshood (Fig. 138), columbine, 

 larkspur, and jimson weed (Fig. 146) acts in much the 

 same way. Clamping the dry peduncle of any one of 

 these ripe fruits, so as to hold it upright above the table- 

 top, and then swinging it back and forth, will readily 

 show its efficiency in seed dispersal. 



