172 



BIOCHEMICAL SYSTEMATICS 



Mothes and Romeike (1955) have questioned the use of iso- 

 quinoHne alkaloids to relate the Papaveroideae and Fumarioideae to 

 each other, yet by the same data to relate the Papaveroideae to other 

 Ranahan famihes. They consider that such conclusions represent 

 circular reasoning. However, there are two levels of similarity in- 

 volved, and the evidence should be applied independently at different 

 levels. For example, various types of isoquinohne alkaloids occur in 

 the different famihes of the Ranalian complex, and it is merely the 

 presence of the general isoquinohne type that ties the groups together, 

 while, in addition, in the Papaveraceae it is the common presence 

 of a series of specific isoquinohne derivatives, some rare, which is con- 

 sidered to be especially significant in adducing the relationship of the 

 sub-families. 



Comparison of certain alkaloids of the Ranunculaceae and 

 Berberidaceae proves to be interesting. In the Ranunculaceae, 

 Xanthorhiza, Coptis, Thalictrum, and Hydrastis produce isoquinohne 

 alkaloids. Except in Hydrastis the alkaloids are relatively simple 

 protoberberines. Species of Hydrastis contain hydrastine, a more com- 

 plex phthahdeisoquinoline, found only in Berberis laurina of the 

 Berberidaceae. In the Berberidaceae, Berberis, Mahonia, and Nandina 

 are alkaloid producers. Protopine, otherwise restricted to the Papaver- 

 aceae, is found in Nandina, and Nandina lacks the bis-benzyliso- 

 quinolines found in other Berberidaceae. It is interesting that Hutch- 

 inson (1959) and other workers have placed Nandina in a monotypic 

 family, Nandinaceae. Generally, the alkaloid distribution in Berberi- 

 daceae and Ranunculaceae does not suggest any unusually close re- 

 lationship between the two families. However, an interesting proposal 

 was published in this connection by McFadden (1950). McFadden 

 recognized a "small chromosome group" of five genera in the Berberi- 

 daceae: Nandina, Berberis, Jeffersonia, Hydrastis, and Glaucidium. 

 Basic chromosome numbers in this group vary from x = 6 to x = 14. 

 In the Ranunculaceae six genera also form a "small chromosome" 

 group (Gregory, 1941): Isopyrum, Aquilegia, Anemonella, Thalictrum, 

 Coptis, and Xanthorhiza. Basic chromosome numbers for these genera 

 range from x = 1 to x = IS. The isoquinohne alkaloids are found, in 

 the two famihes, only in the small chromosome groups. According to 

 McFadden: 



From a morphological standpoint, treatment of this group of genera as 

 a systematic unit is at least as tenable as their present classification. 

 However, in grouping these genera as a taxonomic unit morphological 

 characters would be stressed that are different from those now em- 

 ployed by classification of these. 



