32 THE EVOLUTION OF PLANTS 



the parasitic plants of this class, which emulate 

 Fungi, and live at the expense of some other 

 plant on which they prey. Some parasites are 

 only half-and-half robbers, making some of 

 their food for themselves, and taking the rest 

 from their victim. This is the case with green 

 parasites, such as the Mistletoe, the best known 

 of all; also the Eyebright and Money (Rhinan- 

 thus cristagalli), which are parasitic on roots 

 and may do a good deal of harm; there is a 

 saying that "The farmer who has money in his 

 fields has none in his pocket." But others, like 

 the Broom-rape and the Dodder, have lost their 

 green colour and live altogether on the unhappy 

 plants which they infest. The Dodder has prac- 

 tically no leaves or roots; it looks like a mere 

 tangle of twine, on the furze-bush or other 

 victim, until it begins to flower, and its true 

 nature is revealed. This degradation of the 

 vegetative body of the parasite in consequence 

 of its living on the fruits of other plants' labours, 

 goes much further in some tropical forms. In 

 the famous Rafflesia Arnoldi, a parasite on 

 Sumatran vines, the flower is the biggest in the 

 world, a yard in diameter, but nothing else is 

 to be seen. Stem, leaves and roots have all dis- 

 appeared and are represented only by a web of 

 threads, like the spawn of a fungus, burrowing 

 in the substance of the plant attacked. Thus 



