1917] WYLIE—VALLISNER1A 137 





the pond. A count of several of these flower masses showed an 

 average of over 2000 flowers packed within each spathe, the whole 

 group the homologue of the single pistillate flower w 7 hich is solitary 

 within its spathe. The staminate inflorescence resembles a large 

 fern sorus surrounded by an indusium. This similarity is carried 

 further by the striking resemblance of the slender-stalked unopen 

 staminate flowers to polypod fern sporangia. Massed within the 

 spathe these flowers are joined to the axis by slender pedicels of 

 varying length, so as to completely fill the space between the 

 stem and the spathe. 



The pollen-bearing flowers are very tiny, less than 1 mm. in 

 diameter before opening, and are simple in structure. The floral 

 parts consist of 3 sepals, 2 functional stamens, and rudiments of 

 petals. The sepals are of unequal size and are not symmetrically 

 disposed; 2 are similar and stand nearly opposite; while the third 

 and smaller one is placed laterally between them. This reduced 

 sepal is the first to open. Numerous tapering and curved hairs 

 cover the region about the base of the stamens and are doubtless of 

 some importance, although their functions are not clear. The 

 2 stamens stand close together and have their parallel filaments 

 united up to a point near the anthers (pi. IX). 



At maturity the tip of the spathe opens slightly and the stami- 

 nate flow r ers begin detaching from their slender stalks. The upper- 

 most are the first to be shed, and 2 or 3 days may be necessary to 

 empty a single spathe. These detached flowers rise slowly through 

 the water to the surface and there very slowly open. In this 

 respect Vallisneria stands in sharp contrast to the writer's (2) 

 observations on Elodea canadensis. In that form the staminate 

 flowers upon release dart to the surface and there fairly explode, 

 scattering their pollen on the surface of the water. In Elodea, 



that the sepals of the 



however, it is the free floating pollen that fun< 



neria the pollen retained in the anthers has 



reaching the stigmas. Svedelius (3) 'reports 



detached staminate flowers of Enalus acoroides snap back upon 



reaching the surface of the water, although the pollen is retained 



in the anthers. In Elodea canadensis, and perhaps in Enalus, the 



snap of the sepals seems to be due in part at least to the release of 



