224 



HYDROCHARIDE^E. 



[CLASS 



As pistillate flowers only are found, no seeds can be per- 

 fected, so that the multiplication is solely by the breaking 

 up of the plant into fragments, each fragment originating 

 an independent plant. 



A South European species (Vallisneria siralis), with 

 long narrow leaves, is Commonly grown in fresh-water 

 aquariums. The small pistillate flowers rise, upon a 

 sender peduncle, to the surface of the water in which 

 the plant grows, reaching a great length when the water 

 is deep. The staminate flowers, on the other hand, are 

 sessile near the root ; and when their pollen is ripe, they 

 break off from the plant and float to the surface, where 

 they fertilize the stigmas. The leaves are well adapted 

 for showing the " rotation " of the cell-sap under the 

 microscope. 



66. Natural Order Liliaceae. The Lily Family. 



DISTRIBUTION. A large Order, numerously repre- 

 sented in each quarter of the globe. British genera r/ } 

 species 30. 



Herbs (or a spinose shrub). Perianth-segments petaloid, stamens 

 6 (except Paris}. Ovary superior. 



FIG. 169. Vertical section of flower of Wild Tulip. 



Type Wild Tulip (TuKpa sylvestris}. 



