Eucalyptus is a genus of trees and bushes belonging to the Myrtaceae family. They are the most widespread trees in Australia. There are more than 700 species of eucalyptus of which almost all are native to Australia. However, some species are also found in New Guinea, Indonesia and the Philippines.
Currently many of these are cultivated for ornamental or productive purposes in the temperate zones of the American continent, of Europe, of Asia and of Africa. They are very common only in these areas because most of them are not rustic. Eucalyptus is actually just one of three very similar and close genera that are often confused. The others are called Corymbia and Angophora.
Some of these are nicknamed "rubber trees" because of the latex that comes out if their bark is engraved. The name eucalyptus it derives from the Greek and means "well hidden" with reference to the fact that the petals initially hide the center of the flower.
Originally from Tasmania, it is a tree that can reach 25 m, but can also be cultivated as a splendid shrub, maintaining its size at about two meters with appropriate pruning. As a tree it provides a slight shade, suitable for protecting forest specimens placed at its feet, the shrub form is pruned annually and preserves the rounded leaves of gray-blue cholera used in floral compositions. The genus eucalyptus includes about seven hundred species of evergreen trees and shrubs , all originating from the Australian continent;
Eucalyptus gunnii is a medium-sized, evergreen tree, which in nature can reach 25-30 meters in height, but remains smaller in European gardens. It has an erect trunk, very robust, with gray bark, which tends to break into red scales with the age of the plant; the crown is oval, not too wide; it is a very vigorous plant, which can grow even a meter every year, but can be kept compact with frequent pruning.
The young foliage is oval, bluish green, it becomes lanceolate with the age of the plant, of dark green color; plants pruned up to large shrubs tend to maintain the juvenile shape of the leaves. In summer it produces small pompon flowers, white or greenish, followed by small roundish fruits, containing seeds.
The eucalyptus foliage contains a very aromatic essential oil, used in herbal medicine and also by the pharmaceutical industry; these trees are known as gum trees, due to the abundant sap flowing from each cut made in the bark. In Italy, other species of Eucalyptus are also cultivated, such as Eucalyptus coccifera, with a light brown, smooth bark; Eucalyptus globulus, with showy semi-woody buds, and almost blue-blue foliage; Eucalyptus cinerea. In some parts of Italy, such as in Liguria, the eucalyptus they are grown to make fronds for the cut flower market. Strict motions can also be pruned, to keep the plant compact or to remove damaged parts; the eucalyptus tends to develop without problems even and pruned at the base.
EUCALYPT IN BRIEF
|Main varieties||Eucalyptus gunnii, Eucalyptus coccifera, Eucalyptus globulus, Eucalyptus cinerea|
|Type of plant||Columnar tree, mostly evergreen|
|Height at maturity||25-30 m in nature, up to 100 meters|
|Cultivation||Easy where the climate is mild, some species resist the cold|
|Water needs||undemanding, avoid stagnation|
|Exposure||sun, sheltered from the wind|
|Place of cultivation||full ground|
|Type of soil||Drained, soft, preferably non-alkaline soil|
|Climate||Generally mild weather, some species resist frost|
An adult eucalyptus has the shape of a very large bush or a large tree.
The specimens can have different shapes depending on the species and the pedoclimatic characteristics of the area in which they grow. They generally range from 10 to over 60 m in height.
Some species of eucalyptus they can be counted among the tallest trees on the planet. For example, the Eucalyptus regnans is the tallest flowering tree in the world. One of its specimens reaches almost 100 m in height. Almost all of them are evergreen even though some tropical species lose their leaves at the end of the dry season. Like myrtle, the leaves produce aromatic oil.
To obtain a healthy plant it is well vigorous to place the eucalyptus in a sunny place sheltered from the wind. Eucalyptus gunnii does not fear the cold, but part of the foliage can be ruined by intense motorcycle winter winds; fortunately most of the eucalyptus trees tend to repair cold damage, producing new leaves with the arrival of spring, even starting from mature wood. There are many species of eucalyptus that can withstand even intense frosts for quite long periods of time. They also sustain pollution and the salty wind of the coasts without problems. It requires full sun.
They can withstand even prolonged periods of drought or strong humidity in the ground without problems. It is common to water the young plants recently placed at home, at least every 2-3 weeks, during the summer.
They prefer soft and fresh soils, well drained and free from water stagnation; however, they are satisfied with any soil, even rocky or poor in nutrients. It hates alkaline soils but adapts to any type of well-drained and moist soil.
It usually occurs by seed, in spring; or it is practiced by taking semi-woody cuttings in late spring. It multiplies by seeds, to be spread in spring and autumn. Deep vessels are used for root development.
Pests and diseases
These vigorous plants are not attacked by pests or diseases; the damages that often mark the external part of the crown are due to particularly intense cold or to strong winter winds.
It has shallow roots, which can be easily damaged during processing. These plants can have very deep roots, which can even reach 2.5 meters.
Another interesting feature of theirs is the presence of accumulation organs at the height of the collar. These allow the plant to overcome long periods of drought and to throw new branches after a fire has destroyed the aerial part. Only thanks to this feature can it survive in some extreme areas of Australia.
Dark green ovate, sometimes sticky.
The leaves are different in the various stages of plant development. Four phases can be distinguished:
- From seed
The juvenile leaves are round, glaucous and sessile. As adults instead they become lanceolate with a hooked apex, smooth on both sides, alternate and of a medium glossy green. Some varieties, however, retain young leaves even from adults and are therefore highly appreciated from an aesthetic point of view.
White, feathery and fragrant; The detail that makes the eucalyptus plants more recognizable are the inflorescences and the fruits.
The flowers, in groups, are made up of many soft and long stamens that can be of various colors: red, pink, fuchsia pink, cream, yellow or white. Before opening they are closed in an operculum composed of petals and sepals merged between them. When the flower opens the operculum falls.
The fruit is woody and almost always has a cone shape. When opened, drop the seeds, yellow-brown, about 1 mm in size.
Most species begin to flower only when they reach the adult stage.
It prefers a temperate climate; in colder regions it is advisable to mulch the base of the plant in the winter and repair it from the wind.
To give the desired shape to the plant, it must be pruned in late spring; when the shoots reach about thirty centimeters, one chooses one that will become the shaft of the tree, all the others are eliminated and the chosen one is tied to a guardian to keep it well straightened.
If you want a shrubby habit, every year in late spring all the shoots are pruned about five to fifteen centimeters from the base.
The appearance of the eucalyptus bark varies with age. Eucalyptus trees create a new layer of bark every year. This helps to widen the diameter of their trunk a lot. Some particular species, however, lose the superficial layer of bark every year and usually fall into strips or pieces.
Species and hybrids
There are more than 700 species of eucalyptus. Some are isolated species and are by their general characteristics very different from the others: they can be traced back to the genus only by observing some details.
Most, however, belong to groups of species very similar to each other, grown in nearby areas and in nature in contact with one another. This is why very often some hybrids were initially classified as new species, especially before genetic analysis could be performed.
Most eucalyptus trees do not tolerate cold, or at most can withstand light frosts (not below -5 ° C). The most tolerant are the so-called "snow gum" like Eucaliptus pauciflora, able to withstand even -20 ° C. Even two subspecies (niphophila and debeuzevillei) are even more rustic and able to withstand very cold temperatures. Some rustic hybrids also come from Tasmania: Eucalyptus coccifera, Eucalyptus subcrenulata and Eucalyptus gunnii. They were then used to produce ornamental plants that are very cold resistant for non-temperate areas.
Animals that live in symbiosis with the eucalyptus
Many marsupials living in Oceania, on the other hand, manage to tolerate it well. They cannot tolerate some other toxins that are always produced by this tree. However, they have the particular ability (especially the koalas) to recognize the leaves that are edible from those that are potentially harmful.
The flowers of the eucalyptus trees produce abundant nectar which is the basis of the nourishment of many insects, birds and bats. The plant is also known for its "insecticidal" capabilities. Effectively removes insects thanks to the scent and secretions on its leaves.
Unfortunately, eucalyptus trees catch fire very easily. This is because of the abundant oil that their leaves produce. This turns out to be highly flammable and causes fires to spread very rapidly (especially in Australia and New Zealand, where there are no natural barriers such as rivers or mountains). However, many eucalyptus trees can survive because often the fire is concentrated in the upper part, on the crown of the tree. The lower part, thanks to the accumulation organs near the roots, is able to regrow new buds, which previously were dormant below the thick and hard bark.
Cultivation and use
Eucalyptus trees have been brought from Australia to the rest of the world since Cook's first trip in 1770. With him was a botanist expert, Sir Joseph Banks, who was immediately enthusiastic about it.
They were consequently introduced in California, Brazil, Colombia, Ethiopia, Morocco, Portugal, Israel, Greece, Spain, Portugal and Italy.
Their plantations have different purposes:
- production of paper: the eucalyptus fibers are particularly short and are indispensable for producing high quality, very smooth, homogeneous and opaque paper.
- The production of is also important firewood, pellets and coal. In fact, its ability to grow rather quickly is exploited. They are also, as we have said, capable of regrowing very vigorously from the roots and therefore, in the poor areas of the planet, they are considered an easy means of supplying firewood.
Precisely for this reason, however, in some areas they are also considered very invasive plants, which take away space from the native flora.
Eucalyptus trees have very deep roots and the ability to absorb a lot of water from the roots and then disperse it in the air through transpiration. They can also reduce soil salinity.
For this reason they have long been used for the reclamation of marshy and malarial areas: for example in Lebanon, in California and also in Italy. In fact it was used a lot in the reclamation of the Agro Pontino and other marshy areas. They were excellent both for draining water and as a barrier for tornadoes (frequent in those areas). In this way (and also thanks to the ability to ward off insects) it contributed to greatly reducing the Anopheles mosquito populations and consequently the incidence of malaria. Today it is considered a spontaneous plant.
Eucalyptus oil is extracted from the leaves. It can be used as a solvent in industry and for the production of detergents because it has antiseptic and deodorant properties. It has the ability to be a good insect repellent and is associated with lemongrass in various products, it is also used in small quantities in the food industry for the production of flavorings, decongestant candies and sweets. Eucalyptus honey maintains its antiseptic and expectorant characteristics.
Diffusion in Italy
In Italy they arrived in the mid-1800s. There was a good spread in the south of the peninsula, in Sicily and Sardinia. As we have said, they were widely used as a windbreak barrier and for the reclamation of marshy areas. The most widespread variety is E. camaldulensis.
It is also known as Tasmania snow gum. It has round, glaucous juvenile leaves. The adult ones are lanceolate from green to blue-green, 5 cm long and 2 wide.
It has a smooth white bark that flakes off in long sheets. It comes from the mountain habitats of Tasmania. The tree has an expanded shape and can reach 25 m in height.
It is very decorative. It has almost round to ovate leaves, about 10 cm long, shiny blue-gray. The juvenile and adult leaves are similar. The bark is white and the flowers are white-cream. It comes from the hills of Tasmania. It reaches 15 meters and has a wide column.
It has lanceolate, round, young adult leaves, up to 18 cm long. The young women are bronze, then blue-green. The plant carries both developmental stages simultaneously. The bark is gray-brown and flakes in large blades. The flowers are white in groups of three.
It can reach 30 m and has a wide column.
The juvenile leaves are round, up to 4 cm long. The adults are lanceolate, 10 and long 4. The bark is gray, green or orange, very decorative, which breaks up into large fragments. It comes from alpine forests, it can reach 25 m and has a wide column.
Eucalyptus - Eucalyptus: Eucalyptus seeds
An eucalyptus can be obtained by gamica or agamic origin, meaning it can be grown either starting from a seed or starting from a portion of a plant such as a branch or a leaf through a typical cutting. Clearly there must be climatic conditions to ensure that the plant takes root and grows and that the seed germinates.
To start a seed cultivation it is advisable to first germinate the seed and this operation can be carried out either starting from a cotton cultivation or by sowing the eucalyptus directly in the ground.
In the case of cotton germination we put the seed in wet cotton and wait for it to germinate. If instead we want to make it germinate from the soil we put it in a jar with quality soil and water. We wait a few days and a small plant should emerge from the ground.
Eucalyptus, a common name for eucalyptus, belongs to the Myrtaceae family and is a tree native to Australia
visit: eucalyptus plant
The 600 species of trees and large shrubs gathered under the genus Eucalyptus (from the Greek "to hide") come from the kings
visit: eucalyptus tree