MISCELLANEOUS COMPOUNDS 



273 



logical criteria. As more information has become available concerning 

 the pigments of the so-called "lower plants," the situation has become 

 increasingly complex. The concept of characteristic pigments for 

 particular major taxonomic categories has not been seriously affected, 

 and the validity of pigment characters as distinguishing attributes is 

 maintained. However, statements concerning the over-all phylogeny 

 and the positioning of the groups relative to each other must be 



PHAEOPHYTA 



Phaeophyceae 



Heterokontae <- 

 (Xanthophyceae) 



Chrysophyceae 



Pyrrophyta 



Chlorophyta <- 



Cryptophyta 



-^-^J---- 



Euglenophyta 



Purple bacteria 



Rhodophyta 

 (Rhodophyceae) 



--> Green bacteria 



•-> Cyonophyceae 



COMMON PRIMITIVE ANCESTOR 



Fig. 14-1. Hypothetical phylogenetic relationships of certain bac- 

 terial and algal groups based in part on carotenoid biochemistry, 

 (courtesy of Dr. T. W. Goodwin). 



