HOW TO KNOW THE SEAWEEDS 



158b Cortex composed of cells usually showing little or no arrange- 

 ment in anticlinal rows; medulla with refractive filaments. Figs. 

 198, 201 Cryptonemia 



Fig. 201. Cryptonemia obovata 

 J. Agardh 



Habit of a young plant, X 0.36. 

 This is one of two species which 

 may be encountered frequently in 

 beach drift along the Pacific 

 Coast. Unhke Grateloupia or 

 Halymenia, the blades are not 

 sHppery in texture, but rather 

 firm and crisp. The blades are 

 reduced at the base to a very 

 slender, short stipe. 



Figure 201 



159a Tetrasporangia developing between the medullary filaments. Figs. 

 199, 202 hidophycus 



Fig. 202. Ihdophycus ilacci- 

 dum Setchell & Gardner 



Habit of a young plant, 

 X 0.32. This is a common 

 species of a genus of sever- 

 al species occurring from 

 central California northward. 

 hidophycus grows mostly at 

 low intertidal levels, and 

 sometimes in great abund- 

 ance. /. flaccidum and at 

 least one other species have 

 been harvested commercial- 

 ly in Oregon and northern 

 California for the production 

 of the phycocolloid Iridophy- 

 cin used in stabilizing choco- 

 late milk. As much as 400 



Figure 202 



pounds have been collected by one man at a single low tide. 



153 



