3 1 2 BIOCHEMICAL SYSTEMATICS 



among the hybrids, these two oils were generally in lesser amounts 

 than was typical of the respective parents. This is the case even 

 though both do not occur together in one plant, so it is not directly 

 the result of the presence of two oils rather than one. In contrast, 

 certain other constituents found in lesser amounts than geranyl 

 acetate and cineole in both parental species (for example, eudesmine, 

 sesquiterpene, and an unidentified fluorescent compound) were more 

 abundant in a large number of the hybrids. Another example of this 

 sort is reported by Schwarze (1959), work to be discussed later. 



Eudesmol, found in greater amount in E. macarthuri, is 

 present in intermediate quantity in most of the hybrids. 



The rather considerable variation observed among the hy- 

 brids is consistent with their F2 origin. However, the fact that no 

 hybrids were detected with oil characteristics even close to those 

 of either parent suggests an intricate genetic basis governing both 

 the quantitative and qualitative aspects of oil character. That in 

 an F2 population oil yield was not significantly above that of the 

 low yield parent is also surprising. Since F2 leaf shape is clustered 

 near that of E. cinerea this fact tends to reduce the likelihood that 

 the low yield typical of the F2 results from a favoring by selection of 

 the E. macarthuri genome or back crossing to E. macarthuri. In Fi 

 progeny of a cross between E. pauciflora and E. dives and also hy- 

 brids of E. pauciflora and E. robertsonii oil yield was clearly inter- 

 mediate though covering a large range among the different individuals. 

 In yet another inter-specific cross, this time between E. maidenii and 

 E. rubida, oil yield in the hybrids was entirely within the range of the 

 high-yield parent {E. maidenii). Obviously no generalizations concern- 

 ing the inheritance of yield are permitted from these data. 



Recombination between biochemical characters and morpho- 

 logical characters was also in evidence. For example, two hybrids with 

 a leaf shape approaching E. cinerea were high in geranyl acetate con- 

 tent. According to the authors the data suggest "rather free recom- 

 bination" between leaf shape and geranyl acetate content. 



Additional significant findings in this research are the facts 

 that in no case in a hybrid were both geranyl acetate and cineole ab- 

 sent, and one hybrid was notable in having an oil content of specific 

 gravity and high levo-rotation, suggesting as a possibility the presence 

 of substantial 1-pinene. Aside from this observation, for which there 

 is no additional evidence, there was no indication of the occurrence of 

 compounds in the hybrids not present in either parent. Yet, as the 

 authors maintain, the amounts of several components in the hybrids 

 exceed substantially the amounts of those components in either 

 parent (Table 15-1). 



