HOW TO KNOW THE SEAWEEDS 



150a Thallus with a disc-shaped holdfast. Fig. 189 



Phyllaria dermatodea 



Fig. 189. Phyllana dermatodea (De la Pylaie) Le 

 Jolis 



The lower part of a plant showing the simple, 

 discoid holdfast and the entire, Ugulate blade, 

 X 0.22. 



Found on surfy rocks at lowest tide levels and 

 below, from northern Massachusetts northward. 



The form of the blade is Hke that of several 

 species of Laminaria, especially some of the nar- 

 row Pacific Coast forms. 



150b Thallus with a holdfast of branched hapteres 

 Laminaria (in part) 



Except for the type of holdfast, which is like 

 that in Fig. 187, the several species of Laminaria 

 which key out here are of the Ugulate, non-flabel- 

 late form shown in Fig. 189 for Phyllana. Such 

 forms are represented on the Atlantic Coast by 

 Laminaria agardhii Kjellman (from New Jersey to 

 Cape Cod) and by L. faeroensis Borgesen (Maine). 

 Several Pacific species are of this narrow form, 

 at least in young stages, but one will encounter 

 on either coast a range of variation among the 

 species extending from the narrow, Ugulate blade 

 to the broadly cordate or flabellate and lacerate 

 blade of Fig. 187. 



Figure 189 



146 



