214 



Minnesota Plant Life. 



Bulrushes. Here are also the bulrushes and their allies, a 

 number of which are natives of the state. The most common 

 bulrush is the one that forms beds at the margins of many 

 Minnesota ponds and lakes, This plant has stout creeping 

 rootstocks which branch underneath the soil of the bottom. 

 Lateral branches of the main stem arise into the air, growing 

 sometimes from seven to nine feet tall, with a few sheathing 

 leaves at the base and a leaf or two at the point where the flower- 

 cluster branches originate. The erect stem as a whole is a 

 slender green cylinder, whip-shaped and beautifully constructed 

 to withstand the wind and surf of its habitat. The bulrush is 

 an example of a small adapta- 

 tional group known as surf- 

 plants. The leafless character 

 of the stem may be regarded 

 as the result of experience in 

 surfy water, for in such a posi- 

 tion the leaves, if they had 

 existed, would probably have 

 been torn away and the plant 

 has therefore learned how to 

 exist without any leaves over 

 the principal portion of its sur- 

 face. 



There are a variety of rea- 

 sons why different p 1 a n t s 

 abandon their leaves. Some- 

 times the leafless habit is an adaptation to very dry atmospheres ; 

 therefore a number of desert plants are leafless, because if they 

 had leaves they would tend to transpire moisture more rapidly 

 than they could absorb it. Again, the absence of leaves may 

 be an adaptation to strong winds ; thus the switch-plants on the 

 islands of the Adriatic may be regarded as varieties which have 

 abandoned their leaves because of the frequency of violent blasts 

 that would be likely to tear or destroy them. In the bulrush, 

 however, the leafless habit is partly a response to the prevalence 

 of surf in places where the plant is accustomed to make its 

 home. 



FIG. 95. Bulrush-sedge. After Brittou and 

 Brown. 



