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 T'rapa 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 
