92 THE HUMAN SIDE OF PLANTS 
ground soon to germinate and spring into new 
plants. 
Another kind of clinger is the cockle-bur. These 
burrs also are covered with tiny sharp hooks, which 
are terrible indeed when embedded in the skin of 
animals, for they are almost impossible to shake 
off or pick loose. These plants frequent pasture 
lands and the burrs are especially prone to ride 
on horses’ tails. 
Still another clinger is the sand-spur, which grows 
abundantly in open fields and in dry desert places 
of America. The spurs are the seeds of a peculiar 
form of sand-loving grass; and when once they get 
a start in a new region it is practically impossible 
to free the land of them. These spurs attach 
themselves to animals, and often lacerate their flesh; 
sometimes they so completely cover the feet of dogs, 
or even of children, that it is impossible for them 
to walk until the spurs are removed. Occasionally 
the seeds fasten themselves in an animal’s mouth, 
causing it to suffer severe pain; they often attach 
themselves to the beaks of doves and various prairie 
birds. 
Every one has possibly seen the stick-tights— 
or has acted as their unwelcome beast of burden! 
How harmless the little akenes (seed-pods) with 
their tiny spiked horns appear! All the summer 
