6o WONDERS OF PLANT LIFE 



charming Snowflake, a plant which is probably not 

 a native, spreads amazingly by means of its seeds ; 

 these are encased in a capsule which readily floats. 

 On the Loddon, a tributary of the Thames, the 

 species has spread up and down the stream 

 amazingly, and it is gradually extending to the 

 main river. As years go by it is likely that the 

 Snowflake will become increasingly plentiful, until 

 it is distributed throughout the Thames water- 

 system. An astonishing illustration of the dis- 

 tribution of a plant by water is that afforded by 

 the American water-weed Elodea Canadensis, a 

 species which somehow was introduced into Britain 

 about sixty years ago. In this short while it has 

 managed to spread over most of the water-ways 

 of Great Britain. Indeed, in many districts the 

 plant has blocked canals to such an extent that 

 it has proved a real hindrance to navigation. 



The number of seeds which are distributed by 

 animal agency is immense. All kinds of devices 

 are adopted to secure the conveyance of the seed 

 from its parent to a distant situation where it 

 will stand a reasonable chance of securing room 

 for development. Those seeds having hooked 

 vessels exhibit a variety of method which is 

 amazing. Some, like the Martynias of America, 

 are provided with hooks many inches in length ; 



