FATTY ACIDS 



131 



carbon-methyl flavonoid component of wax is suspected (Price, 1962). 

 For separation of alkanes, the techniques of gas chromatography and 

 mass spectrography are utihzed together. 



Purdy and Truter (1961) have compared the surface hpids of 

 leaves of sixty three species, using thin layer chromatography to sep- 

 arate mixtures. Characteristic patterns were obtained for each species. 

 It was also demonstrated that the patterns did not change with the 

 age of the plant. 



The work of Eglinton et al. (1962) is of unusual interest and in- 

 dicates that wax constituents may be of exceptional taxonomic value. 

 These workers chromatographed unfractionated extracts of alkanes, 

 using only 40 g. of dried samples, and obtained a complete analysis of 

 straight chain and branched chain alkanes of 23 to 35 carbons. Some 

 of their results are shown in Fig. 7-2. The variety of patterns dis- 

 closed by their data suggests wide application of these methods in 

 taxonomy. 



The patterns of alkanes derived from individual species are 

 apparently quite constant. A study of Aeonium urbicum (Crassulaceae) 

 collected from various places and including immature and even dead 



Crassulaceae 



13 



-il4 



' 



vA 



15 



Scrophularicceae Euphorbiaceae 



17 



^ 



Gramineae 



Liliaceae 



Solonaceae 



Cruciferoe 



18 



19 



22 24 26 28 30 32 34 



22 24 26 28 30 32 34 

 Carbon No. 



22 24 26 28 30 32 34 



22 24 26 28 30 32 34 22 24 26 28 30 32 34 



n n— alkane 



■ Branched chain alkane 



Fig. 7-2. Distribution in mole percentage of n- and branched 

 chain alkanes C22-35 in the hydrocarbon fraction of the waxes 

 from individual plant species. Alkane percentages less than 2 mole 

 per cent have been omitted (Courtesy G. Eglinton). 



