188 PLANT LIFE 



from the vine. The filamentous strands in- 

 crease at the spot where a flower is to develop, 

 and a sort of ball of tissue is formed which 

 presently bursts through the rind of the Cissus 

 stem. Presently the ball splits open, and 

 there grows out from within it a flower bud 

 which opens out into the single enormous 

 blossom. 



A more familiar flowering parasite is the 

 Dodder. This plant infests various hosts, 

 e. g. flax, clover, nettles, gorse, etc. It 

 rather suggests in appearance bundles of 

 pink string thrown at random over the vege- 

 tation. It belongs to the convolvulus family, 

 and still more or less retains the twining habit 

 so characteristic of many of its relatives. But 

 whereas the leafy convolvulus merely supports 

 itself by twining round its support, the almost 

 leafless dodder puts forth suckers where its 

 stem is in contact with that of its host, and 

 from the central portion of each sucker a 

 growth is formed which penetrates the plant. 

 In this manner the dodder obtains the whole 

 of its food, both water and organic substance. 



Although the dodder is really little more 

 than a specialised twining convolvulus, never- 

 theless, in relation to its parasitic habit, it has 

 ceased to form green leaves, and it is not even 

 rooted in the soil. It is true that when the 

 seed first germinates it is anchored by hairs 

 to the ground, but the lower part of the stem 

 soon dies away, and the whole plant comes to 

 be absolutely dependent on a parasitic life. 



