FIG. 166. Eel grass (Vallisneria), a common pondweed plant. The plants are 
anchored and the foliage is submerged. The carpel-bearing flowers are carried to 
the surface on long stalks which allow a variable depth of water. The stamen- 
bearing flowers remain submerged, as indicated near the lower left corner, the 
flowers breaking away and rising to the surface, where they float and effect pollina- 
tion. After KEKNER. 
