Question on Eucalyptus for distillation

During the course of the month I receive many interesting questions regarding the world of natural essences. The subject as a whole is vast, intricate and intriguing and I enjoy doing my best to share what I can on various points that might help give some insight into this enchanting world. Recently a customer was enquiring about and essential oil that is very common, Eucalyptus oil. They were asking if there was an essential oil distilled from fresh leaves.
The answer is yes, but one needs to know exactly how the distiller is going about collecting the leaves. If Eucalyptus is grown under cultivation then the grower, in many instances, tends to keep the trees closely clipped for ease of harvest(as Eucalyptus trees can grow very tall if simply grown for reforestation or an ornamental purposes) If they keep the trees short and then regularly prunes them(which in some instances can be 3-4 times a year but generally twice) then the leaves that they will use for distillation will be fresh. But it is also important to remember that the chemistry of the oil may also vary during the time of year the leaves are harvested. The combination of day length, season, water(or lack thereof) and many other minute factors influence how the life energy moves in the tree, consequently effecting the chemistry not only day to day but hour to hour. Of course the species of Eucalyptus also helps determine the chemistry of the oil but the chemical balance within that species does fluctuate because of many environmental factors, timing of harvest etc
Other distillers may be producing their oils from wild grown trees and in that case the leaves used for distillation may be older than those grown under cultivation as such trees will not be clipped regularly as mentioned above. Lastly the exact location where an oil is grown plays an important role in determining the olfactory qualities of the oil. Even a simple oil like Eucalyptus globulus may reveal different aromatic facets depending on where it is grown.
I have smelled oils from Nepal, South Africa, Australia and India and each has its own unique aroma.
Aside from the above mentioned issues regarding harvest, the way in which the oil is distilled of extracted plays a significant role in determiining the olfactory qualities of an oil. Every distiller has their own way of distilling Eucalyptus-some preferring hydrodistillatlon, some steam distillation, etc. Some use crude iron vessels, some glass, some stainless steel. Then each distiller has their own distillation “technique” that is the parameters that they develop for their equipment  for the distillation of a particular oil. Each and every small detail from harvest to distillation plays a vital role in determining the olfactory qualities and the chemical balance of each oil.
Above I have mentioned mainly factors in oil quality that effect the quality of a distilled oil but if one were to then take the same botanical material
and submit it to extraction to produce a co2 extract or an absolute they would again enter another world of olfactory variance. For instance Eucalyptus globulus leaves are also extracted to produce and absolute and if one were to smell the absolute next to its essential oil, one would hardly recognize that both were taken essences from the same botanical material. The high, sharp, penetrating green, medicinal notes of the essential oil are not at all present in the absolute which displays a soft  ambery, green, resinous, fruity, balsamic, woody bouquet.
Indeed volumes could be written on this subject from different angles, but I hope these few words might prove interesting to the reader. The more one ponders on the subject the more one senses how amazing it is that nature provides us with such exquisite essences of aromatic beauty.

Links concerning Eucalyptus distillation


Historical Footage of the Eucalyptus Oil Industry on Kangaroo Island 

History of Eucalyptus Oil

Eucalyptus Oil harvest and production at Emu Ridge | Emu Ridge