16 



anther 

 ,— filament 



Figure 7. 

 Sagittaria teres: A. habit of partially submersed 

 plant, X Vz. B. habit of emersed plant, x Vi. C. fruiting 

 head, x 1 Vi. D. achene, x 5. E. stamen showing pubes- 

 cent filament, x 5. 



