PLANTS THAT MIMIC 31 



a leafless parasite which in Mexico grows on a 

 leafless cactus. 



Among the desert plants, the cacti claim a large 

 share of natural likenesses. These, as well as other 

 succulent plants, which find it necessary to store 

 up sweet juices for their own use during the long- 

 continued droughts, would be entirely destroyed 

 by thirsty and hungry cattle and other animals 

 were it not for their ability so to imitate their 

 surrounding by mimicking the grey pebbles and 

 sands as to pass unnoticed. 



The ice-plant, one of the Mesembryanthemums, 

 covers its head with a hoar-frost, for all the world 

 like a piece of ice; but the sun does not melt it, 

 nor do the rains dissolve it! Other forms of the 

 Mesembryanthemums are composed largely of suc- 

 culent shoots, and so closely resemble the stones 

 surrounding them that they pass unnoticed by hun- 

 gry and thirsty animals, and are thus allowed to 

 flourish even in the deserts of South Africa. 



Almost every species of animal or insect has its 

 imitator in the plant world: the horse's shoe is 

 imitated by the Hippocrepis; the bull's head is rep- 

 resented by the Trapa bicornis. There is a species 

 of lotus which greatly resembles the foot of a bird, 

 including the toes. Some of the lupines have seeds 

 strikingly like tarantulas; and the seeds of the 



