178 BIOCHEMICAL SYSTEMATICS 



others, for example V. nigrum, contain relatively few alkaloids. The 

 apparent difference may, however, reflect merely a more intensive 

 examination of one species. One should give more consideration to the 

 presence of a given alkaloid then to its apparent absence. In the 

 alkaloids, in particular, as a result of the fact that many alkaloids are 

 drugs, designation of a species as alkaloid-containing is based upon 

 arbitrarily designated minimum quantities. Hegnauer (1958) has 

 recommended that an alkaloid content of 0.01 per cent dry weight 

 represents the minimum in order for a plant to be considered alkaloid- 

 containing. Yet, in considering the taxonomic implications of alkaloid 

 distribution the more relevant data may be the presence of an 

 enzymatic mechanism for synthesis of even a small amount of a 

 particular type of alkaloid. Ability to accumulate the alkaloid in rela- 

 tively large amounts may also be genetic and therefore relevant, but 

 not necessarily as fundamental as the existence of the enzymes in- 

 volved in the primary pathway. For example, in the Solanaceae only 

 traces of nicotine occur in tomato and other species, but from a 

 phylogenetic, if not physiological, point of view the trace is quite 

 important. 



In the literature of alkaloids, particularly, there are examples 

 of rather arbitrary taxonomic revisions by chemists, based principally 

 on chemical evidence. Thus Manske (1954) transferred Dicranostigme 

 franchetianum to the genus Stylophorum "because its alkaloids are 

 the same as those of S. diphyllum." Dicranostigme lactucoides was 

 retained "because the contained alkaloids, namely protopine, isocory- 

 dine, sanguinarine, and chelerythrine present a combination hitherto 

 encountered only in a Glaucium.'" Nowhere was there any discussion of 

 the basis for the previous taxonomic dispositions of the species. The 

 chemical evidence may be important, but it is possible that equally 

 significant morphological or cytological evidence was ignored. 



Another example of arbitrary taxonomic "revision" prim£irily 

 on chemical grounds is that of Manske and Marion (1947) in Lycopo- 

 dium. This paper appeared in the Journal of the American Chemical 

 Society. Lycopodium annotinum var. acrifolium contained five alka- 

 loids absent from typical L. annotinum (they apparently replaced a 

 group of five alkaloids of the latter). Accordingly, L. annotinum var. 

 acrifolium was raised to specific rank, L. acrifolium, with the addi- 

 tional comment that the newly elevated species was more different, 

 morphologically, from L. annotinum, than the two species, L. flabelli- 

 forme and L. complanatum were from each other. This comparison 

 was presumed to lend additional validity to the taxonomic disposition 

 which otherwise was based solely on chemical data. However, Wilce, 

 a student of Lycopodium has stated (personal correspondence): 



