PLANTS RIDE ON ANIMALS 91 
thus travel around; others ride in the water attached 
to fish that may happen to swim their way; still 
others watch for insects on which they may steal a 
ride; but a favourite device with many is to ride 
on animals, or even people. 
The kinds of plants which ride on animals must 
be able to catch hold of the animal as he passes by, 
or stops to graze, as a boy “hops” a passing car. 
To this end, plants which travel on animals have 
many clever tricks whereby they may catch and 
cling to the passer. Some carry a diversity of 
hooks, claws, and grapnels. Some have developed 
certain shapes and devices for clinging; others have 
formed the most fantastic and demoniacal methods 
of holding on to the unfortunate animal to which 
they have attached themselves. 
Among the simpler clingers is the common bur- 
dock. The seeds of this plant are very troublesome, 
and have become so well adapted to travelling by 
using the peculiar, tiny hooks or claws which aid 
them to cling, that they are very widely distributed 
over the earth. They mount the tails of horses and 
cows, cling to the fleeces of sheep and goats; and 
sometimes even steal a ride on a Jack-rabbit! Burrs 
of this type are filled with large seeds, and they 
remain attached to the animal until they find a suit- 
able home or place to live, when they drop to the 
