161. Eucalyptus regnans. 



M . in Report Acclm. Soc, \ i< I 

 Giant Gum-tree. 



Systematic. A tree .it lasl stupendously tall; bark outside whitish and 

 smooth except at the stem base; leaves of young seedlings opposite, sessile, 

 cordate-roundish, whitish from wax} bloom; leaves ol rather thin texture, from 

 elongate to bnud lanceolate, much unilaterally curved, shining on both sides 

 their secondary venules slightly spreading; oil-dots extremely numerous and 

 pellucid ; umbel- mostly solitary. 



Fruit. "Quite small, generally semi-ovate its 

 border depressed or nearly flat; valves 

 em losed." 



The fruits ar,- rather smaller than E. Delegatensis, 

 which they somewhat resemble in shape. 



Habitat. Victoria , I asmania. 



REMARKS, rhe description given h re is taken verbatim from Mueller's " Dichotomous Ki \ to Victorian 

 Plants " and is so i xplii i1 th it th l1 botanist tnusl h ive h id a strong sp :< i s in vii n a1 the time oi founding E. regnans. 

 Deane and Maiden (Proc. Linn. Soc, N.S.W., 1899, P- l'"' 1 synonymise their own species, E.fastigata, with it; but 

 as it is impossible to reconcile the Baron's description with the speoifii characl 1 oi theirtree a Eucalyp 

 known to us. we retain the two as distinct pecii fh tn known as E. regnans in Casmania has < im t <• a smooth 

 li.irk. whil ■ E. fastigata has .1 stringy bark. Maiden (Crit. Rev., vol. I, p. 184) still later adheres to his classification 

 ..I E. fastigata. 



ESSENTIAL OIL. Material for distillation was collected on Mt Welling- 

 ton, Tasmania, in July, iqo8. One sample of leaves with terminal branchlets 

 was collected at a height of about 2,000 feet above sea-level, and another at about 

 2,500 feet. This tree is known locally in Tasmania as " Swamp Gum." The oils 

 from both consignments were alike, showing that a difference in alt tude has 

 little influence on the secreted oil. The composition of the oil was also in agree- 

 ment with that of E. regnans, from material sent for distillation from Yarra Junction, 

 Victoria, by Cuming, Smith, and Company. This agreement is shown by the 

 appended results, and is particularly marked with those derived from the several 

 fractions. The comparative absence of dextro-rotatory pinene in the oil of 

 E. regnans shows it to be a species distinct from E. fastigata, irrespective of botanical 

 differences. 



The oil of E. regnans consists largely of the terpene phellandrene, and 

 contains a fair quantity of the stearoptene eudesmol. This substance was obtained 

 in larger amount than is usual, by increasing the pressure of steam after the oil 

 had distilled off in the usual manner ; on allowing the distillate to remain for some 

 hours in open vessels, the eudesmol could be removed as a crystalline fat-like 

 mass from the sui fai e of the water, and purified in the ordinary way. 



The presence ol cineol was doubt lul even in the portion distilling at about 

 176 C, so that this frequently occurring constituent in Eucalyptus oils was only 

 present in traces in that of E. regnans. The ester appeared to be almosl entirely 

 geranyl-acetate, as it saponified readily in the cold with two hours' contact. The 

 ketone piperitone was nub, presenl in small amounl A considerable portion of 

 the nil consisted of high-boiling constituents, probably the sesquiterpene ]argehj ; 

 and the high-boiling fraction soon became solid alter separation, due to the 

 present e of the eudesmol. 



