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upon the shore as are favorable for 

 rockweeds (Fucus) or Enter omorpha. 

 A long exposure at low tide is not ad- 

 vantageous for their growth. Thus 

 Postelsia, and certain varieties of Alaria 

 which grow at the highest level, select 

 stations where they are constantly wet 

 by the surf, and Postelsza, in particular, 

 is one of the most beautifully adapted 

 of all the surf plants. Others are cov- 

 ered at mid-tide, and here again the 

 peculiarities of the different genera will 

 be evident. Hedophyllum, for example, 

 not so strongly anchored a plant, pre- 

 fers quieter nooks, while Lessonia, with 

 its strong trunk and firm anchorage, 

 maintains itself in powerful surge. Still 

 other kelps select lower levels, and are 

 not exposed, even at low tide. Thus 

 Costaria is rarely uncovered, Pterygo- 

 phora grows on the bottom of deep 

 tideways, and Nereocystis floats its 



