214 BIOCHEMICAL SYSTEMATICS 



The existence of colorless anthocyanins in numerous monocot and 

 dicot groups was noted, though they were not detected in certain 

 families which are predominantly aquatic, for example, Potamogeto- 

 naceae. In most cases the pigments are cyanidin derivatives, the most 

 commonly encountered types of anthocyanins in vegetative tissue. 

 The formation of these colorless anthocyanins may involve some type 

 of selection which results in the appearance of a physiological state 

 permitting the anthocyanins to exist in the pseudobase form. Possibly, 

 some of these may have been misidentified as leucoanthocyanins. 



Some recent phenolic studies having systematic implications 

 are those of Pecket (1959, 1960a, 1960b) on Lathyrus; Griffiths (1960) 

 on Theobroma and Herrania; Reznik and Egger (1960) and Egger and 

 Reznik (1961) on Hamamelidaceae and Anacardiaceae; Bate-Smith 

 and Whitmore (1959) on the Dipterocarpaceae; Bate-Smith (1961) on 

 Prunus and Potentilla; Riley and Bryant (1961) on Iridaceae and 

 Billek and Kindl (1962) on the Saxifragaceae. In each of these studies 

 variations in patterns were observed, though the authors did not in 

 all cases consider the systematic significance of the patterns. Perhaps 

 more important than the establishment of taxonomic affinities at this 

 stage of such work is the fact that species can be distinguished from 

 other related species by the phenolic characters compared. 



In the Lathyrus study several systematic judgments were made 

 on the basis of the various phenolic patterns established for certain 

 species, but the present writers, after examining the data offered, and 

 in consideration of the general characteristics of the compounds, would 

 be more conservative. In a genetic study of Lathyrus odoratus (Beale, 

 1939), flavonoid inheritance was shown to be quite complex with a 

 number of chemical phenotypes represented within a single species. 

 However, it is true that wild species, such as those studied by Pecket, 

 tend to have fewer variations than cultivated species. If the results of 

 studies of the comparative chemistry of the non-protein amino acids 

 of Lathyrus (Chapter 6) and the toxic nitriles (Chapter 10) are 

 integrated with the phenolic data, interesting taxonomic conclusions 

 may be possible. 



Some of these phenolic studies tend to exaggerate the 

 systematic implications of the data. It is natural that enthusiasm 

 will sometimes exercise a subtle influence to magnify the positive as- 

 pects of interpretation, but the occasional direct assertion that the 

 particular biochemical data do not provide any clues to systematic 

 relationships should be anticipated. When only a few compounds are 

 being considered and when only a few individuals of a selected group 

 of species are screened, such results would not be cause for repudia- 

 tion of the methods, nor would they even be surprising. Studies such 

 as that of Stoutamire (1960), though preliminary in nature, show a 



