Flowers. 



179 



FIG. 94 . 



boat-shaped Fruiting Scale or Carpel from a 

 young Pine Cone. A, seen from 

 the front, showing two ovules; 

 B, diagram of a longitudinal 

 section of A, seen from the side. 

 m, micropyle ; n, embryo sac. 

 A, after BESSEY ; B, after CALD- 

 WELL. 



is readily dispersed from flower to flower at any depth. 



In the case of Vallisneria spiralis 



(see Figs. 95-96) the pistillate 



flowers rise to the surface on 



slender stems. The staminate 



flowers, which are formed under 



the water, break loose from their 



stems and float on the surface, the 



calyx consisting of 



sepals which buoy the stamens 



above the surface, and allow them 



to float high and dry. The sta- 

 mens bend outward beyond the rim 



of the calyx, and when the stami- 

 nate and pistillate flowers 

 are brought together by the 

 wind or currents of water, 

 the anthers come in contact 

 with the stigmas and effect 

 their pollination. The stem 

 which bears the pistillate 

 flowers then coils itself spi- 

 rally and draws the flower 

 to the bottom of the water, 

 where the seeds may ma- 

 ture undisturbed. 



129. Adaptations to In- 

 sects. The most wonder- 

 FIG. 95. f ul modifications of flowers 



Vallisneria spiralis. The plant on the left are found in those f OrniS 

 bears staminate flowers which are break- 



ing away and rising to the surface. The which are adapted to CrOSS 



plant on the right bears a pistillate flower pollination by means of in- 

 rising on a long stem to the surface. 



After KEENER. sects. These have had to 



