zgg 



16L Eucalyptus regnans. 



(F.v.M., in Report Acclm. Soc., Viet., 20, 1870.) 

 Giant Gum-tree. 



Systematic. A tree at last stupendously tall; bark outside whitish and 

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

 cordate-roundish, whitish from waxy bloom; leaves of rather thin texture, from 

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

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

 pellucid ; umbels mostly solitary. 



Fruit." Quite small, generally semi-ovate its 

 border depressed or nearly flat ; valves 

 enclosed." 



The fruits are rather smaller than E. Delcgatensis, 

 which they somewhat resemble in shape. 



Habitat. -Victoria ; Tasmania. 



REMARKS. The description given here is taken verbatim from Mueller's " Dichotomous Key to Victorian 

 Plants," and is so explicit that that botanist must have had a strong spscics in view at the time of founding E. regnans. 

 Deane and Maiden (Proc. Linn. Soc., N.S.W., 1899, P- 4 6 ) synonymise their own species, E.fastigata, with it; but 

 as it is impossible to reconcile the Baron's description with the specific characters of their tree, a Eucalypt well 

 known to us. we retain the two as distinct species. The tree known as E. regnans in Tasmania has quite a smooth 

 bark, while E. fastigata has a stringy bark. Maiden (Crit. Rev., vol. I, p. 184) still later adheres to his classification 

 of E. fastigata. 



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

 ton, Tasmania, in July, 1908. 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 surface of the water, and purified in the ordinary way. 



The presence of cineol was doubtful 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 almost entirely 

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

 ketone piperitone was only present in small amount. A considerable portion of 

 the oil consisted of high-boiling constituents, probably the sesquiterpene largely ; 

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

 presence of the eudesmol. 



