HOW TO KNOW THE SEAWEEDS 



75b Branching not regularly alternate, or at least without a branch 

 from each cell of the main axis. Fig. 109 77 



Fig. 109. Spermothamnion turneri 

 (Martens) Areschoug 



A small upper portion of a fer- 

 tile plant showing multifarious 

 branching and presence of axial 

 cells without branches, X 75. This 

 is a common small epiphyte on 

 Chondrus and Phyllophora in in- 

 fratidal waters along the Atlantic 

 Coast south of Cape Cod. It may 

 be 2 to 5 cm, tall and is usually 

 found in summer in tetrasporic 

 condition. Note that another spe- 

 cies of Spermothamnion from the 

 Pacific Coast (See Fig. 112) has 

 distinctive polysporangia. 



Figure 109 



76a Asexual plants bearing tetrasporangia. (See Fig. 108) 



Callithamnion 



(In part; see also step 31b and Figure 52) 



85 



