212 



BIOCHEMICAL SYSTEMATICS 



Smith states that among sympetalous families, those with zygomor- 

 phic flowers often lack flavonols in the leaves, and this fact may pro- 

 vide a clue to the morphological character with which the absence of 

 flavonols might be linked. It is important to establish any correlation 

 between metabohsm and form since the biochemical basis of develop- 

 ment in all its stages is so little known. However, the present writers 

 beheve that many, if not most, secondary compounds have no critical 

 role in morphogenesis, and consequently correlations between a given 

 chemical and anatomical character may be merely coincidental. 



Many biochemical studies of phenoUcs have emphasized the 

 distribution of some of the commonest phenolics, for example, fla- 

 vonols and certain cinnamic acid analogs such as ferulic and caffeic 

 acids. This trend is natural, particularly when investigations are con- 

 ducted by biologists who must rely upon relatively simple chemical 

 procedures. However, in many cases the actual systematic value of the 

 studies may not be great, particularly when minor systematic cate- 

 gories are being considered. As illustrations of the broad distribution 

 of certain phenolics, Tomaszewski (1960) surveyed 122 species of 86 

 famihes for p-hydroxybenzoic acid and other simple phenols and 

 found that p-hydroxybenzoic acid was present in 120 of the 122 

 species tested. Caffeic acid was present in all but about a dozen 

 species. [The author stated that caffeic acid was absent from all 

 gymnosperms and legumes, but none of the species investigated in 

 the study was named, and since, of 122 species, a total of 86 different 

 families was included, not many gymnosperms or legumes could have 

 been examined. Pecket (1959) found caffeic acid in most species of the 

 legume, Lathyrus.] Ferulic acid occurred in 63 per cent of the species. 

 p-Coumaric acid occurred in all but three genera, but catechol was 

 found only in the Salicaceae wherein it occurred in all species examined. 

 Takahashi et al. (1960) found quercetin and kaempferol to be widely 

 distributed in the order Coniferae, and no significant pattern was 

 estabhshed. The chief significance of these studies is the additional 

 evidence adduced for a very wide distribution of certain phenohcs. 

 This fact does not exclude them from systematic utility within a 

 particular taxonomic group, since in combination with other chemical 

 constituents they might prove significant in individual cases. 



An extension of such investigations to the more complex or 

 the more restricted phenoHc types should yield data of more obvious 

 meaning, in some cases even at the infra-specific level. One excellent 

 example has been described by Wilhams (1960). Apple and pear 

 are significantly different in their phenohc chemistry, the distinc- 

 tions remaining consistent even though individual varieties (cultivars) 

 of apple fruit (but not leaves) vary greatly in this respect. Apple 



