452 Minnesota Plant Life. 



pollination is the rule. Where they are inconspicuous, as in 

 the pondweeds and water milfoils, wind pollination is the rule. 

 A peculiar case is that of the eel-grass, which produces its 

 pollen-bearing flowers in large numbers on submerged spikes. 

 Each pollen flower separates from the spike and rises to the 

 surface of the water, where it opens. The pistil-bearing flow- 

 ers are produced singly on the ends of long, thread-like stems, 

 and open at the surface of the water. The little pollen-pro- 

 ducing flowers are blown about like so many tiny sail-boats, 

 either striking their stamens against the stigmas of the pistil- 

 late flowers, or giving the wind an opportunity to carry the 



^FiG. 223. Trees along a river bank. Soft maple and cottonwood. Minnesota river. 

 After photograph by Williams. 



pollen from one flower to the other. In the naiads and in some 

 of the pondweeds, the pollen-spores are carried in the water, 

 by ripples on its surface, from one flower to the other. The 

 majority of these water plants retract their fruits under the 

 surface to ripen them. Sometimes the stem of the fruit-bear- 

 ing flower shortens spirally, coiling down into the water as in 

 the eel-grasses. Sometimes the stem curves and thrusts the 

 young fruit under the surface. A few water plants mature the 

 fruits above the surface of the water, and of such the Indian 

 lotus is an example. 



