PARASITE PLANTS. art 
Plants are subject to the attacks of other 
plants which grow upon and even within them. 
Some of these actually live by drawing away the 
sap of the plants or trees on which they luxuriate ; 
but others, like the beautiful orchids represented 
growing on the branches of that dead tree in 
the cut, simply rest upon the tree and do not 
derive anything from it, living upon the air, and 
only putting forth a sufficiency of small roots on 
the branch on which they repose, to secure them 
to it, while they send out their large roots into 
the air around. The mistletoe, on the other hand, 
is a true parasite,—that is, really and truly lives 
by sucking the juices of the tree on which it 
grows. 
These “parasites” are of a large size, and their 
deleterious influence on vegetable life is exercised 
only on one or two individuals in a hedge-row or 
field. The most alarmingly destructive are of a 
very minute size, and in fact only to be seen by 
the help of the microscope; and these may some- 
times cause terror to an entire nation by the 
ravages they commit among plants upon which we 
depend for our food. The blights of wheat are, 
several of them, of a vegetable nature, consist- 
