HOW PLANTS PROTECT THEMSELVES 



847 



growths are known from their discoverer as Belt's bodies. 

 The ants bore holes into the large hollow stipular thorns 

 shown in the figure, live in these thorns, feed on the 

 Belt's bodies, and protect the acacia from insect and other 

 enemies. A nectary on the leaf furnishes additional food 

 to the ant inhabitants of the tree. A great multitude of 

 plants, some of them herbs, offer more or less important 



leaflet 



' ■ FlQ. 242. — An Ant-Plant (^cacto). 



t, thorns ; h, hole in thorn ; n, nectary ; 6, Belt's body on tip of leaflet. 



inducements to attract ant visitors ; the species which are 

 known to do this number over three thousand. 



415. Plants which mimic Plants or Other Objects. — 

 Instances of mimicry of protected plants by unprotected 

 species are not very common. One of the best-known 

 cases is that of the dead-nettle, which is so ca,lled because 

 it looks like the stinging nettle, though it is perfectly 

 harmless. Some South African plants {Kleinias) appear 

 to mimic pebbles. Certain Mesembryanthemums of the 



