RED ALG^. 195 



It grows in deep water, on stones and weeds, from 

 a discoid root, with a short stem, which immediately 

 flattens into a thin, wedge-shaped, repeatedly forked 

 membrane, two to eight inches high, widely spreading, 

 the lobes from one-fourth to one-half an inch wide, 

 with parallel sides and rounded apices. Tlie color 

 varies from a pink to a full red. 



The fertile fronds may be known by the interrupted 

 or broken line of very dark red fruit vessels, which 

 runs up the middle of the frond and its segments, 

 quite Hke a midrib. The barren plants hive an 

 appearance much like that of Rhodymenia corallina, 

 but may usually be distinguished from that species, 

 by their much brighter red color. Fronds bearing 

 asexual fruit are dotted over with irregularly shaped, 

 dark red spots. It is reported on the whole coast 

 of Calfornia, but not very common anywhere. 



Genus. — PIKEA^ Harv, 



Ptkea californica, Harv. 



This is a common, coarse, cartilaginous plant, 

 growing between tides at all seasons along the whole 

 California coast. It has a thickish, narrow, flattened 

 frond, one-eighth of an inch wide, three or four 



