142 



BOTANICAL GAZETTE 



[FEBRUARY 



stigmas 



released when the group was submerged, has again entered the 

 film pocket. This resulted from being blown into the radius of the 



declined surface. 



Each passing wave thus brings a shift in the position of the 



flowers and furthers the wearing away of the pollinia upon the 



the time that the pistillate flower is at the surface 



the events outlined may 

 be repeated hundreds of 

 times with varying de- 

 grees of submergence. 

 At all times, of course, 

 there may be additions 

 to the group from the 

 free floating staminate 



flowers. 



Attention 



Fig. 4. — Pistillate flower has been pulled 



should be directed to 

 the fact that any degree 



farther down in water; depression is cup-shaped, of depression is helpful, 

 and staminate flowers stand at right angles to the j i.i i. 



verticle walls. 



com 



mergence 



probably occurs frequently, is not necessary to adequate pollination. 

 When the pistillate flower is finally withdrawn into the w T ater by 

 the coiling of the scape, numerous pollen-bearing flowers may be 

 trapped in the bubble of air that forms about the retreating floral 

 parts as they disappear beneath the surface. As the 1 



1m 



5 volume of 

 the pollinia 



more and more strongly into the stigm 



Obser- 



vations on isolated patches of pistillate plants show that the scapes 



will coil somewhat without 



the 





flowers are present. At the first favorable opportunity the writer 



plans to make a study of the flowering habits of marked plants 



in the field to determine the length of time the flowers remain at 



the surface, and the influence of pollination upon the time of their 

 retreat. 



Despite the dioecism and complete separation of the flowers in 

 Vallisneria, pollination seems to take place with remarkable 



