BOTANY FOR YOUNG PEOPLE. 125 



Elizabeth, on the Vallisneria, a plant that grows 

 partly under water, belonging to the Class Di- 

 O3cia. The male of the Vallesneria has a long 

 spiral stem, by which its flower is at all times 

 enabled to adapt itself to the surface of the 

 water, from the bottom of which the plant shoots 

 forth, and to float in the middle of tide streams 

 of almost eveiy variation of ascent. The stem 

 of the female is straight and much shorter, and 

 is consequently only found in shallow waters, 

 or on shores where the tide exerts but little in- 

 fluence. They thus live remote from each 

 other and yet it is absolutely necessary that the 

 pollen of the male should be thrown on the stig- 

 ma of the female, or no seeds would be pro- 

 duced, and the species become extinct. The 

 mode by which this is done, is, as Dr. Good re- 

 marks, truly wonderful for the distance, as well 

 as the water, precludes the use of the wind or 

 insects. As soon as the male flower ripens its 

 pollen, its spiral stem dies by the want of the 

 nourishment which is absorbed by the flower, so 

 that at the moment of its perfection, the stem 

 bursts, and the flower separated from it sails 

 from shore to shore in pursuit of its companion, 

 for the most part, driven by the current of the 



