242 



128. Eucalyptus Irbyi, s p . 



nov. 



Systematic. A small tree, with a smooth, pale or ashy-coloured bark. 

 Abnormal leaves broad-ovate to ovate, sometimes mucronate, petiolate, base 

 rounded, truncate or slightly cordate, fairly thick and coriaceous. Normal leaves 

 coarse, lanceolate to broad-lanceolate, or even ovate, acuminate, up to 8 inches 

 long, mostly straight, on unusually long petioles; venation often indistinct, 

 intramarginal vein looped, well removed from the edge, lateral veins spreading, 

 distant, inclined at an angle of 30-40 to the mid-rib. Peduncles angular, 

 axillary, i to 2 lines long, bearing umbels of mostly three flowers. Buds shortly 

 pedicellate; calyx tube turbinate, 2 lines in length; operculum blunt, conical, 

 often slightly broader than and more than half as long as the tube. 



Fruit. Hemispherical to sub-cylindrical, glaucous, 

 or shining; rim flat to convex, often 

 somewhat depressed, cracked transversely ; 

 valves more or less exserted; 3 lines long 

 and 3 lines in diameter. 



Some of the fruits are so like the hemispherical form 

 of E. Gunnii that when the material was first collected 

 it was placed tentatively with that species until other 

 characters could be worked out, but it is, however, a 

 much coarser plant morphologically than that species. 



Habitat. Alma Tier, Interlaken, Tasmania. 



REMARKS. Mr. L. G. Irby (Conservator of Forests of Tasmania) was instrumental in first bringing 

 this species forward. He discovered it on the Alma Tier, Interlaken, Tasmania, growing amongst . Gunnii, and 

 thought at first it was E. viminalis from the abnormal leaves, but noted its differences in other respects from the 

 normal material of that species c.ollected in other localities in Tasmania during his trip. An exhaustive oil 

 determination, made since publishing our Research on the Eucalypts of Tas., Roy. Soc., 1912, confirmed our 

 suspicion that it was new. In that paper it was placed tentatively under E. viminalis. The chief specific differences 

 from this latter are the broader abnormal and normal leaves, both of which are much coarser than those of 

 E. viminalis, and are always affected with a fungus, whicl is never so in E. Gunt-ii or E. viminalis, and which gives 

 the whole plant a black, dirty-looking appearance. This is evidently a specific character by which it can be 

 determined, just as in the case of E. camphora. The fruits are, however, identical in shape with those of E. Gunnii, 

 from which species it differs in the physical features of its bark lacking the sweet nature of the sap of E. Gunnii. 

 which can always be obtained by cutting the bark, and from which it derives its common name of " Cider Gum." 

 In foliage it is not unlike E. Dalrympleana, J.H.M. Its affinities He equally between E. viminalis. on the one hand, 

 and E. Gunnii on the other, so that in a systematic arrangement it might be placed between these two. 



ESSENTIAL OIL. Leaves and terminal branchlets for distillation were 

 obtained at Interlaken, Tasmania, in August, 1912. The yield of oil was 0-15 per 

 cent., and it contained pinene, phellandrene, cineol, and the sesquiterpene. 



The crude oil had specific gravity at 15 C. = 0-9021 ; rotation a D - - 1-7; 

 refractive index at 20 = 1-4829, and was soluble in 4 volumes 80 per cent, alcohol. 

 The saponification number for the esters and free acid was 8-5. 



On rectification, i per cent, distilled below 167 C. (corr.X and between 

 167-185, 66 per cent, distilled. The remainder, which consisted largely of the 

 sesquiterpene, was not distilled. 



The rectified oil had specific gravity at 15 C. = 0-886 ; rotation a D + 6-4 ; 

 and refractive index at 20 = 1-4760. 



The cineol was determined by the phosphoric acid method in the rectified 

 portion ; when calculated for the crude oil, the result was 15 per cent. 



