36 THE BOOK OF NATURE STUDY 



ing plant obtains by its roots water and salts from the soil. It 

 obtains the carbon it requires, not from the soil but from the carbon 

 dioxide present in the air. From those simple raw materials an 

 independently living green plant builds up the complex substances 

 it needs for its growth. The construction of the root system and 

 the shoot with its expanded green leaves was seen to stand in 

 relation to this mode of nutrition or feeding. The two plants to 

 be described do not grow rooted in the soil, but attached to other 

 plants which are spoken of as host plants. They derive their 

 food from the host plant, and are termed parasites or parasitic 

 plants. Their form and structure will be found to be more or 

 less modified according to their more or less complete parasitism. 



The Dodder is a total parasite, and derives all its food ready 

 made from the host plant on which it lives. It departs more 

 widely from the ordinary appearance of a flowering plant than 

 does the Mistletoe. There are several species of Dodder found in 

 Britain, but they differ only in minute features, and any one will 

 serve for study. The commonest kind is Cuscuta Epithymum, 

 found growing on Heather, Furze, Thyme, etc. on heaths and 

 commons. C. europea often occurs on Nettles, while C.Epilinum 

 is a parasite upon Flax, and may be found where this plant is 

 cultivated. The appearance of the Dodder is so peculiar and 

 characteristic that little difficulty will arise in identifying it when 

 it is met with. The mature plant has no connection with the 

 soil, and consists of thread-like pink stems twined round the plant 

 on which it is growing and spreading to neighbouring plants. The 

 host plant always suffers from the growth of the parasite on it, 

 and the infected areas in a field of Clover or Flax may be visible 

 from some distance. 



If portions of the host plant with the Dodder attached are 

 collected in summer, complete material for the study of the mature 

 plant will be obtained (Fig. 9, A). The whole plant has a pinkish 

 colour. The green colour so characteristic of most plants is 

 practically absent, only a trace being found even on the most 

 careful examination. The slender stem twines round that of the 

 host plant, grasping it firmly at places in two or three coils. Other 

 portions of the shoot hang free from the host, and may come into 

 relation with adjoining plants, thus spreading the Dodder locally. 



