HOW TO KNOW THE SEAWEEDS 



179a Ultimate flattened branches, especially of fertile plants, arranged 

 in clusters or fascicles along the major axes which are more or 

 less cylindrical. Fig. 226 Odonthalia 



Figure 226 



Fig. 226. Odonthalia Uoccosa (Esper) Falkenberg 



A small part of a mature plant to show the fasciculate arrange- 

 ment of the ultimate, short, flattened, acute branchlets, X 1. This is 

 the most widespread of our species of this genus. It ranges from cen- 

 tral California northward. In the Puget Sound area of Washington 

 several other local or far northern species occur. They, however, are 

 more flattened, lack the fasciculate arrangement of the branches and 

 are regularly, alternately, distichously branched Some of them show 

 a more or less distinct development of a midrib. 



On the Atlantic coast the odonthaUas occur north of Maine and 

 outside the scope of this book. 



The student should note that this plant is keyed out here under 

 the flattened species on account of the flatness of the ultimate, acute 

 branchlets. but the often cylindrical character of the axes may at times 

 cause one to attempt to key it out among the cyUndrical ones in the 

 vicinity of step 33. 



179b Ultimate branches not arranged in clusters, 



180 



180a Growth by means of a single apical cell 



181 



180b Growth apical from a many-celled meristem, not from a single 

 apical cell ^^^ 



170 



