CHAPTER XX. 



Tab. XXXV. — vallisneria. 



Fig. 1. Valisneria spiralis. The female plant, the flowers 

 of which are purple. This is drawn from a specimen in the 

 possession of Dr. Ogle. 



Fig. 2. The male plant, producing white flowers ; these 

 when mature rise hke air bubbles, and suddenly expanding 

 when they reach the surface of the water, float about in such 

 abundance as to cover it entirely. "Thus their pollen is 

 scattered over the stigmas of the first mentioned blossoms, 

 whose stalks soon afterwards resume their spiral figure, and 

 the fruit comes to maturity at the bottom of the water." 



Fig. 3. One of the separated male flowers magnified. 



