PHENOLIC SUBSTANCES 217 



whereas, in Diploxylon only pinosylvin, its monemthyl ether, pino- 

 cembrin and pinobanksin occur. Erdtman states: 



The observed differences between Haploxylon and Diploxylon are of 

 such nature that one is led to conclude that the Haploxylon pines have 

 an oxidation-reduction system at their disposal which has disappeared 

 or is defective in the case of the Diploxylon pines. Since "loss" muta- 

 tions are more common than progressive mutations, it is probable that 

 Haploxylon is more primitive than Diploxylon. Alternatively the 

 separation has taken place already at an earlier phylogenetic stage.2 



Furthermore, Erdtman states that "more powerful methylating 

 systems" are characteristic of the Haploxylon pines, species of which 

 contain carbon methylated flavones and flavanones. 



Outside the genus Pinus some other interesting situations are 

 discussed by Erdtman. For instance, of fourteen Tsuga species known, 

 five were investigated, and all contained the lignan conidendrin, an 

 unusual substance characteristic of Picea. 



H3CO 

 HO 



OCH3 

 H3CO 



conidendrin 



All Larix species investigated contained aromadendrin (2:3 

 dihydrokaempferol) and taxifolin (2:3 dihydroquercetin). 



OH 



aromadendrin 



Taxifolin has also been reported in Pseudotsuga taxifolia. 



2 The argument that Haploxylon is more primitive than Diploxylon may be valid, 

 even on the chemical grounds, but not upon the logic that loss mutations are more fre- 

 quent than progressive mutations, a statement which appears to be a non-sequitur. There 

 are examples, in biochemical systematics in which a "loss" is postulated, and, accordingly, 

 the simpler compound is regarded as phylogenetically more advanced. Thus, Gottlieb 

 et al. (1959) reported that in certain Aniba (Lauraceae) species (for example, 

 rosewood) four methoxylated a-pyrones occur, while in others (for example, coto) only the 

 unsubstituted «-pyrones occur. These authors consider the plain a-pyrones of more recent 

 phylogenetic origin, but their argument rests on the observation that current theories of 

 the biogenesis of a-pyrones involve an expected oxygen fimction at position 4. 



