HOW PLANTS ARE SCATTERED 383 
Why do bur-bearing plants often carry their fruit until 
late winter or early spring? 
What reason can be given for the fact that the burdock, 
the cocklebur, the beggar’s-ticks, the hound’s-tongue, and 
many other common burs, are among the most persistent 
of weeds ? 
453. Uses of Stone Fruits and of Fleshy Fruits to the 
Plant. — Besides the dry fruits, of which some of the 
principal kinds have been mentioned, there are many kinds 
Fic. 272. — Burs. 
A, sticktights ; B, sticktights, two segments, magnified ; 
C, burdock ; D, cockleburs. 
cf stone fruits and other fleshy fruits (Sects. 242-247). 
Of these the great majority are eatable by man or some of 
the lower animals, and oftentimes the amount of sugar 
and other food material which they contain is very con- 
siderable. It is a well-recognized principle of botany, and 
