194 ELEMENTS 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. 
Fic. 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. 
