452 



Minnesota Plant Life. 



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

 the ])on(l\vee(ls and \\ater milfoils, wind ])ollination is tlie rule. 

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

 pollen-hearing flowers in large nunihers on suhmerged spikes. 

 Each pollen tlower sei)arates from the spike and rises to the 

 surface of the water, where it o])ens. The ])istiM)earing 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 tin}- sail-l)oats, 

 either striking their stamens against the stigmas of the pistil- 

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



KiG. 223. — Trees along a river bank. Soft maple and cottonwood. Mitiiiesola river. 

 After photograph by Williams. 



])ollen from one flower to the other. In the naiads and in some 

 of the pondweeds. the ])ollen-s|)()res are carried in the water. 

 by rii)pies on its surface, from one tlower to the oiher. The 

 majority of these water plants retract their fruits under the 

 surface to ripen them, v^ometimes the stem of the fruit-bear- 

 ing llowcr shoricns >pirall\\ coiling down into the watei" as in 

 the eel-grasses, v^ometimes the stem curves and thrusts the 

 young fruit under the surface. .\ few water ])lants mature the 

 fruits abo\e the surface of the water, and of >uch the Indian 

 lotus is an example. 



