917] 



W YLIE—VA LLISNERIA 



141 





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^ 





making conditions more favorable for pollen transfer. The upward 

 movement of the water due to a passing wave might serve to 

 temporarily depress the floating pistillate flower weighted by its 

 long stalk. Should the movement be sufficient to make taut the 

 anchoring scape, even for an instant, the depression would become 

 cuplike, with the inner staminate flowers standing at right angles to 

 its nearly vertical walls (fig. 4). 

 Many of the pollen masses would 

 thus be forced directly into the stig- 

 mas, although the outer ones would 

 still be held back at some distance. 



At a certain 



stage 



of depression, 



however, the lateral pressure of the 

 water breaks the surface film above 

 the flow r er; the sides of the cup snap 

 together, roofing it over; and a con- 

 siderable number of staminate flowers, 

 with the pistillate flower, are thus 



shut tightly together in a 



common 



bubble beneath the surface of the 



water (fig. 



It should be noted 



com 



turned the staminate flowers, and 

 that these are now inverted UDon the 



Fig. 3. — Positions assumed with 

 slight tension on scape of pistillate 

 flower. 



the 



stigmatic surfaces. 



photograph for fig. 5 was taken th 



the 



staminate 



To 



the right may be seen a number 

 that were released from the depr 



the 



the 



again to the surface; the bubble breaks, and most of the flower^ 

 resume their original relations at the surface of the water (fig. 6). 

 Examination, however, shows numerous pollen grains or even 

 entire staminate flowers scattered over the surface of the stigmas. 



Fig. 6 shows that 



grou] 



floating staminate flowers, 



