

136 BOTANICAL GAZETTE [February 



The epigynous seed-bearing flowers of Vallisneria are borne 

 singly, each within its spathe at the end of a long scape, sometimes 

 over a meter in length, which anchors the floating flower to the short 

 upright stem at the bottom of the pond. Upon reaching the sur- 

 face of the water through the elongation of this axis, the spathe 

 opens at its outer end, but remains as a partial investment of the 

 ovary until the seeds are nearly mature. The 3 spoonlike sepals 

 soon separate, disclosing the 3 bifid stigmas which are coiled in the 

 center of the flower (pi. IX). These fleshy stigmas are densely 

 clothed with the stigmatic hairs, and their snowy whiteness con- 

 stitutes the most conspicuous part of the flower. Rudimentary 

 petals and slender staminodia are present, but as they seem func- 

 tionless their discussion may be deferred to a subsequent paper. 



The anchoring scape usually elongates sufficiently to permit the 

 opening flower to assume an inclined position in the water as it is 

 carried to one side by wind or current. The ovary, which is 

 20-25 mm. long before fertilization, is usually straight until the 

 flower opens and has taken its position at the surface; later it 

 often curves considerably in response to gravity, thus bringing 

 the floral parts more nearly parallel with the surface of the water. 

 This bending of the ovary at this stage is quite marked in plants 

 growing in aquaria where the flowers are left undisturbed for some 

 time. 



The exposed floral parts are waxy and consequently are not 

 wetted by the water, with the result that the flower comes to rest 

 with a portion of its weight resting on the sepals and margins of 

 stigmas supported by the surface film. This produces a slight 

 depression of the water about the flower, perhaps 15 mm. in 

 diameter, which is abruptly declined at its inner margin next to 

 the pistillate flower. This sloping surface film plays an important 

 part in capturing the floating staminate flowers, and later is 

 intimately bound up with the actual transfer ,of pollen to the 

 stigmas. Too much emphasis cannot be laid on the complete 

 dependence of this plant upon the surface film of water for its 

 pollination processes. 



The staminate flowers are borne crowded numerously within 

 the globose spathe which remains short-stalked at the bottom of 



