WATER-LILIES 



99 



the whole mass is half-sunk is a flower-cushion or re- 

 ceptacle, formed out of the end of the flower-stalk. The 

 numerous stigmas have a radiating arrangement, as in a 

 poppy, to which the water-lilies are believed to be allied. 

 Nymphsea is pollinated by flying beetles, such as rose- 

 chafers, which are sometimes caught in the closing flowers 

 and drowned. 



After flowering is over the pistil slowly enlarges, and 



FIG. 26. Yellow water- 

 lily. Entire fruit with calyx. 

 Slightly reduced. 



FIG. 27. Yellow water-lily. 

 Fruit beginning to burst. 

 Slightly reduced. 



before long is set free by the rotting of part of the flower- 

 stalk. It sinks to the bottom until the seeds are ripe. 

 Then the envelope bursts, and a rounded mass of slimy 

 seeds is disclosed, which floats up to the surface, and 

 forms patches not unlike fish- or frog-spawn. During 

 ripening each seed becomes invested by a spongy membrane 

 or aril, and air is secreted and lodged in this. The floating 

 seeds are soon dispersed by currents or wind, possibly by 

 birds also. After a few hours the air escapes from the 

 arils, the seeds become waterlogged, and being, like nearly 

 all seeds, heavier than water, they sink to the bottom, 

 where they are destined to germinate. 



