POTAMOGETONS IN RELATION TO POND CULTURE. 



279 



propagative structures characteristic of the species. All of the seedlings produced them. 

 Figure 5 represents the first shoot in a germinating winter bud. It may be assumed from 

 the general behavior of the seedlings and the growth from the hibernacula that in this 

 species vegetative structures only are matured the first year, and that seed formation 

 is deferred at least until the second year. 



At present definite knowledge regarding the young stages of Potamogeton, in 

 general, is very meager and this is doubtless attributable to the fact that the plants are 

 small and inconspicuous the first year and fail to develop fruit until one or more vege- 

 tative reproductions of the plant have taken place. 



PRODUCTION OF SEEDS AND VEGETATIVE PROPAGATIVE STRUCTURES. 



The abundance of P. crispus and P. pectinatus in the local flora have made it possible 

 to observe the relative production of seeds and vegetative structures in a considerable 

 number of these plants. Besides, the formation of the conspicuous vegetative structure 

 in both species is practically synchronous with seed formation. The observations on 

 mature plants selected at random form the basis of the following tables : 



Tabulations of Propagative Structukes in Potamogeton crispus, June 16, 1913. 



(a) bur formation. 



