OF THE VALISNERIA. 335 



the above account highly probable in a coun- 

 try where the sun has so much more power, 

 even if it did not come from the most faith- 

 ful and philosophical 'botanist .of antiquity, 

 and I have always with confidence cited it on 

 his authority. The reader, however, will per- 

 ceive that the only important circumstance 

 for our purpose is the closing of the flowers 

 at night, which is sufficiently well established. 

 But the most memorable of aquatic plants 

 is the Valisneria spiralis, well figured and 

 described by Micheli, Nov. Gen, t. 10, which 

 grows at the bottoms of ditches in Italy. In 

 this the fertile flowers stand on long spiral 

 stalks, and these by uncoiling elevate them 

 to the surface of the water, where the calyx 

 expands in the open air. In the mean while 

 plenty of barren flowers are produced on a 

 distinct root, on short straight stalks, from 

 which they rise like little separate white bub- 

 bles, suddenly expanding when they reach 

 the surface, and floating about in such abun- 

 dance as to cover it entirely. Thus their pol- 

 len is scattered over the stigmas of the first- 

 mentioned blossoms, whose stalks soon after- 

 wards resume their spiral figure, and &e 



3 



