254 BIOCHEMICAL SYSTEMATICS 



These sapogenins were encountered among numerous species 

 of Yucca and Agave as well as other genera of the families Liliaceae 

 {sensu lato), and Dioscoreaceae. Although it is not entirely clear from 

 the text whether all species of the related family, Amaryllidaceae, 

 were negative, a number of species of this family were examined, and 

 the impression gained is that they were negative. Plants which tested 

 negatively were not listed in these references, unfortunately. It was 

 believed at the time the Marker et al. paper appeared that outside of 

 monocots very few plants produced steroidal sapogenins, but more 

 recently reports of their wider distribution, among dicot families, 

 have occurred (Altman, 1954; Anzaldo et al., 1956, 1957; Wall et al, 

 1957). No major effort has apparently been made to evaluate the 

 general systematic significance of the steroidal sapogenins. 



Saponins of the triterpene type have been neglected more 

 than the steroidal saponins. Simes et al. (1959) have recently sur- 

 veyed the flowering plants of eastern Australia for saponins and 

 found them to be widely distributed among numerous families. A few 

 families were singled out as being especially rich in saponin-containing 

 species, but the group does not represent a "natural" one, and its 

 taxonomic value at this stage is probably minor. 



Fontan-Candela (1957) has made a comprehensive survey of 

 the botanical distribution of saponins, including the steroid and tri- 

 terpene types. He notes that saponins in general are found through- 

 out the plant kingdom, while the steroid types are restricted, so far 

 as is known, to angiosperms. Although Fontan-Candela does discuss 

 briefly phylogenetic considerations it is quickly apparent that the 

 wide distribution of saponins among angiosperms prohibits any but 

 the broadest generalizations concerning their systematic value. This 

 is particularly true if one is considering only the presence or absence 

 of saponins. Since many of the surveys do not include characteriza- 

 tion of the specific saponins present in a species, this group of com- 

 pounds suffers from a limitation similar to that of the cyanogenetic 

 glycosides, previously discussed (Chapter 10). 



One exception to the general neglect of triterpene saponins is 

 the excellent work of Djerassi (1957) on the triterpenes of Cactaceae. 

 Djerassi and coworkers investigated forty species representing twelve 

 genera of the giant cacti of the Tribe Cereeae and described a number 

 of new triterpenes. Table 13-3 summarizes the triterpene content of 

 the species investigated. From the systematic viewpoint, it is note- 

 worthy that alkaloids are absent or present in only minute quantity 

 in those cacti which contain the triterpenes, while Lophocereus, with 

 the highest alkaloid content, lacks triterpenes. Certain species of 



