Today I though I'd do somthing on my favorite group of trees, the ecalyptuses.
The leaves are leathery in texture, hang obliquely or vertically, and are studded with glands containing a fragrant volatile oil. The flowers in bud are covered with a cup-like membrane (whence the name of the genus, derived from the Greek eucalyptos (well-covered), which is thrown off as a lid when the flower expands. The fruit is surrounded by a woody, cupshaped receptacle and contains numerous minute seeds.
Eucalyptus trees are quick growers and many species reach a great height. Eucalyptus amygdalinis the talled known tree, some reach to be 480 feet, exceeding in height even the california red wood. Many species yield valuable timber, others oils, kino, etc.There are a great number of species of Eucalyptus trees yielding essential oils, the foliage of some being more odorous than that of others, and the oils from the various species differing widely in character. It necessarily follows that the term Eucalyptus oil is meaningless from a scientific point of view unless the species from which it is derived is stated.
The Eucalyptus industry is becoming of economic importance to Australia, especially in New South Wales and Victoria. Many of the old species which give the oil of commerce have given way to other species which have been found to gave larger yields or better oils. About twenty-five species are at the present time being utilized for their oil.
The oils may be roughly divided into three classes of commercial importance: (1) the medicinal oils, which contain substantial amounts of eucalyptol (also known as cineol) (2) the industrial oils, containing terpenes, which are used for flotation purposes in mining operations; (3) the aromatic oils, such as E. citrodora, which are characterized by their aroma.
The British Pharmacopoeia describes Eucalyptus Oil as the oil distilled from the fresh leaves of E globulus and other species.
E. globulus the best-known variety (its name bestowed, it is said, by the French botanist De Labillardiere, on account of the resemblance of its waxy fruit to a kind of button at that time worn in France), is the Blue Gum Tree of Victoria and Tasmania, where it attains a height of 375 feet, ranking as one of the largest trees in the world. It is also called the Fever Tree, being largely cultivated in unhealthy, low-lying or swampy districts for its antiseptic qualities.The first leaves are broad, without stalks, of a shining whitish-green and are opposite and horizontal, but after four or five years these are succeeded by others of a more ensiform or sword-shaped form, 6 to 12 inches long, bluish-green in hue, which are alternate and vertical, i.e. with the edges turned towards the sky and earth, an arrangement more suited to the climate and productive of peculiar effects of light and shade. The flowers are single or in clusters, almost stalkless.
The Eucalyptus, especially E globulus, has been successfully introduced into the south of Europe, Algeria, Egypt, Tahiti, South Africa and India, and has been extensively planted in California and also, with the object of lessening liability to droughts, along the line of the Central Pacific Railway.
It thrives in any situation, having a mean annual temperature not below 60 degrees F., but will not endure a temperature of less than 27 degrees F., and although many species of Eucalyptus will flourish out-of-doors in the south of England, they are generally grown, in this country, in pots as greenhouse plants.
It was Baron Ferdinand von Müller, the German botanist and explorer (from 1857 to 1873 Director of the Botanical Gardens in Melbourne), who made the qualities of this Eucalyptus known all over the world, and so led to its introduction into Europe, North and South Africa, California and the non-tropical districts of South America. He was the first to suggest that the perfume of the leaves resembling that of Cajaput oil, might be of use as a disinfectant in fever districts, a suggestion which has been justified by the results of the careful examination to which the Eucalyptus has been subjected since its employment in medicine. Some seeds, having been sent to France in 1857, were planted in Algiers and thrived exceedingly well. Trottoir, the botanical superintendent, found that the value of the fragrant antiseptic exhalations of the leaves in fever or marshy districts was far exceeded by the amazingly powerful drying action of the roots on the soil. Five years after planting the Eucalyptus, one of the most marshy and unhealthy districts of Algiers was converted into one of the healthiest and driest. As a result, the rapidly growing Eucalyptus trees are now largely cultivated in many temperate regions with the view of preventing malarial fevers. A noteworthy instance of this is the monastery of St. Paolo à la tre Fontana, situated in one of the most fever-stricken districts of the Roman Campagna. Since about 1870, when the tree was planted in its cloisters, it has become habitable throughout the year. To the remarkable drainage afforded by its roots is also ascribed the gradual disappearance of mosquitoes in the neighbourhood of plantations of this tree, as at Lake Fezara in Algeria.
In Sicily, also, it is being extensively planted to combat malaria, on account of its property of absorbing large quantities of water from the soil. Recent investigations have shown that Sicilian Eucalyptus oil obtained from leaves during the flowering period can compete favourably with the Australian oil in regard to its industrial and therapeutic applications. Oil has also been distilled in Spain from the leaves of E globulus, grown there.
In India, considerable plantations of E globulus were made in 1863 in the Nilgiris at Ootacamund, but though a certain amount of oil is distilled there locally, under simple conditions, little attempt has hitherto been made to develop the industry on a commercial scale, Australia remaining the source of supply.
A great increase in Euealyptus cultivation has recently taken place in Brazil as a result of a decree published in 1919 awarding premiums and free grants of land to planters of Eucalyptus and other trees of recognized value for essence cultivation.