HOW TO KNOW THE SEAWEEDS 



105b Vesicles small, usually not bearing a blade. Fig. 141 Sargassum 



Fig. 141. Sargassum iilipendula C. 

 Agardh 



A small upper portion of a plant to 

 show the leaf-like vegetative blades 

 and the small, subspherical, stipitate 

 vesicles, one of them bearing an abor- 

 tive blade, X 0.64. This is the com- 

 mon, attached Sargassum of the At- 

 lantic Coast from Florida to Cape Cod. 

 The floating species of the Sargasso 

 Sea which are commonly encountered 

 in drift along the south Atlantic and 

 Gulf coasts originate through the 

 movement of the Gulf stream. These 

 are of two kinds, S. iluitans Bdrgesen, 

 and S. natans (Linnaeus) J. Meyen. 



On the Pacific Coast Sargassum oc- 

 curs only in southernmost Cahfornia 

 where a small, densely branched spe- 

 cies, S. agardhianum Farlow, grows 

 on rocky mainland shores while S. 

 palmeri Grunow inhabits the warmer 

 waters of the Channel Islands. 



Figure 141 



106a Thallus flexible, either by joints or because of incomplete calci- 

 fication. Fig. 142 109 



Fig. 142. Bossea sp. 



A small part of a plant, X 5, to 

 show the calcified segments (intergeni- 

 cula) and the short, uncalcified joints 

 (genicula) which provide for flexibility 

 of the thallus. Southern Cahfornia. 



Figure 142 



110 



