Learn all about Eucalyptus trees and shrubs here with this in-depth article setting out the different types of eucalyptus trees and shrubs, size, habitat and more.
Eucalyptus belongs to the family Myrtaceae that has more than 700 species of flowering trees and shrubs. They are commonly known as Eucalypts. Most of the species of Eucalyptus are native to Australia. Most of the trees in Australian forests are Eucalypts. Approximately three-quarter of forests in Australia is Eucalypt forests.
Australian landscapes observe wildfires often. Eucalyptus species are adapted to fire which lets them re-sprout after a fire. Their seeds are resistant to fire which makes Eucalyptus species the dominant plant type in Australian forests.
Some species of Eucalyptus are also found in other countries. They have been grown in numerous countries because they grow fast and provide valuable timber. They are used for plywood and production of honey and essential oils. However, they are flammable which has resulted in their removal from some countries.
Eucalypts have can have a smooth, stringy, or a fibrous hard bark. Their leaves have oil glands, and their petals and sepals are fused together to form a ‘cap’ over the stamens, the fruit of plants in this species is a woody capsule which is commonly known as a gumnut.
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- History of Eucalyptus
- Description of Eucalyptus Plants
- Types of Eucalyptus
- Problems with Eucalyptus Tree Varieties 🔥 TIP: !
- Eucalyptus tree varieties
- Planting eucalyptus trees
- Fragrant Foliage
- Eucalyptus Care Must-Knows
- More Varieties for Eucalyptus
- Eucalypts: 10 things you may not know about an iconic Australian
- What’s in a name?
- The ancient fossil link to Gondwana
- A diverse Australasian
- Bark up the right tree
- There’s oil and gold in them thar leaves
- They’re fruits not nuts
- Reading the fire risk of the country
- By gum, it’s kino
- Summer and winter
- What’s that eucalypt?
- Want more science from across the ABC?
- Garden plant of the moment: Eucalyptus
- Choosing your eucalyptus tree
- Caring for your eucalyptus tree
- Pruning eucalyptus trees
- Eucalyptus Tree Types: Popular Varieties Of Eucalyptus For Landscapes
- Eucalyptus Tree Identification
- Problems with Some Eucalyptus Tree Varieties
- Eucalypt forest
- Distribution and ownership
- Forest structure
- Importance and uses
- Eucalyptus cinerea
History of Eucalyptus
Eucalyptus fossils indicate that their evolutionary roots lie in Gondwana back in time when Australia was connected to Antarctica. They originated from South America, where they are surprisingly no longer endemic. Fossil leaves were also found in New Zealand as well, where they are not present today. The DNA sequencing of Eucalyptus fossils indicates that they are as old as 52 million years.
Description of Eucalyptus Plants
Size and Habit of Eucalypts
Eucalypts range from shrubs to trees. Eucalypt trees usually have a single trunk but some species, like Mallees, are multi-stemmed and are short, rarely taller than 10 meters or 33 feet. A Eucalypt shrub is less than 1m or 3 feet in height and can grow in extreme conditions.
Bark of Eucalypts
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The uppermost layer of Eucalypt bark is replaced every year. in most species, the dead bark is shed as ribbons, small flakes, or as large slabs, exposing a new layer of bark underneath. These species of Eucalypts are called ‘smooth barks’.
Some species are known as ‘half-barks’ in which the dead bark is retained at the lower half of the trunk. It forms a thick accumulation at the base.
The common types of barks that have been registered are;
Stringybark has long fibers which can be pulled off as long piece. These barks are thick and have a spongy texture.
Ironbark is thick, hard, and deeply furrowed. It appears dark red or black because it is impregnated with sap that the tree gives out (dried kino).
- Tessellated Bark
Tessellated bark has cork and they can flake off as it is broken into many flakes.
Box barks have short fibers.
- Ribbon Bark
Ribbon bark is the one that comes off as thin and long pieces but loosely attached at some points. They can be twisted curls, long ribbons, or firmer strips.
Leaves of Eucalypts
Most of the Eucalypts are evergreen but those species which are not losing their leaves at the end of the dry season. The leaves are covered with oil glands, which is a characteristic of Myrtaceae family. The copious oils that these glands produce are an important feature of plants of this genus. The leaves of Eucalypt trees hang downwards.
The leaves of a mature plant in this species are petiolate, lanceolate, apparently alternate, glossy or waxy green. The leaves of the seedling, however, are quite the opposite. They are glaucous and sessile.
The four-leaf phases identified in Eucalyptus plants are a seedling phase, juvenile phase, intermediate phase, and adult phase. The intermediate phase has the largest leaves.
In the majority of species, leaves form in pairs that appear on opposite sides of a square stem. Consecutive pairs of leaves are present at right angles to each other.
Flowers of Eucalypts
Flowers and fruits are the most readily recognizable feature of Eucalyptus plants. Flowers have many fluffy stamens that are white, yellow, pink, cream, or red. The stamens are enclosed in a cap that is called the operculum. Operculum consists of fused sepals, petals, or both. Thus, these flowers do not have petals. They decorate themselves with the showy stamens.
There are numerous varieties of Eucalyptus. Many varieties, ranging from 120 feet tall trees and 4 feet tall shrubs have been widely planted in the U.S.
1. Mallet Eucalyptus
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Mallet Eucalyptus is also known as open-branched forms. They have a single trunk. The branches are angled steeply upwards and they have open space between them. They lack lignotuber and epicormic buds as in Eucalyptus astringens. They fall in the USDA plant hardiness zones 9 through 10.
It is commonly known as the Brown Mallet. It is native to Western Australia’s South West region. It is commonly found on ridges, rocky outcrops, hills, breakaways, and valley floors in Great Southern and South West Goldfields-Esperance and Southern Whaetball regions of Western Australia.
It is found growing in brown clayey sand, red-brown gravelly sand, sandy loam, and laterite, spongolite and sandstone based soils.
Eucalyptus astringens trees are usually 5 to 49 feet tall. The bark of Eucalyptus astringens trunk and stems are grey-brown colored, smooth, and shiny. The leaves are lance-shaped. Flower buds are pendulous and are arranged in clusters of seven. They are cream or pale-lemon colored flowers. The fruit is bell-shaped, cup-shaped, or conical.
The wood from these trees is used for mining timbers, construction, and for making tool handles. It is also suitable to be sued for firewood. The bark is rich in tannin (40%) which makes it suitable to be used for tanning of leathers and for adhesives’ production.
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It is commonly known as the Sugar Gum. It is native to South Australia. It is found in three distinct regions which are Eyre Peninsula, Flinders Ranges, and Kangaroo Island.
It is a fast-growing species. It grows best in sandy, loamy, or clayey soil.
Sugar Gums growing in each region has different features. Sugar gum that grows in Flinders Ranges is usually 115 feet in height. They have a classic gum habit having a straight trunk. The trunk has a diameter of 3.3 to 4.11 feet. Their branches are steep and occur halfway up. Each main branch of Sugar gum ends with a little canopy. They are planted for timber and are cultivated as windbreaks for farms.
Sugar Gum growing in the Kangaroo Island and the Eyre Peninsula are shorter as compared to those growing in Flinders Ranges. They are about 26 to 49 feet tall. Their trunks are crooked and have a diameter of 1.4 feet. The habit of the crown is open spreading. They typically spread from 39 to 49 feet.
The leaves are glossy and discolorous. Flowers are white, cream, or yellow colored. The fruits are barrel-shaped or urceolate and are longitudinally ribbed.
They are planted across Southern Australia to be used as shelterbelt or windbreak, for timber and firewood. The wood from these trees is used in making furniture, posts, flooring, construction timber, and railway sleepers because it is termite resistant.
It is commonly known as the Brittle Gum. It is native to Eastern Australia.
It grows best in soils that contain large amounts of clay, in rocky and shallow soils.
Brittle Gum grows as tall as 20m and spread to about 13m. They have smooth, white colored trunk having grey patches. These grey patches become pink in late spring or in summer. The bark turns into a red color before it sheds. They have an open spreading habit. The limbs are contorted.
The leaves are narrow and are in dull green in color. The flowers are creamy white and grow in clusters during the summer through autumn.
They are grown in gardens, parks, and other areas with open space. They can be used for wider streetscapes. They form a great habitat for native insects and birds.
2. Eucalyptus Marlock
Eucalyptus marlock is densely branched trees. The branches are densely leaved. The leaves of Eucalyptus marlock come all the way down to the ground. They fall in USDA hardiness zones 7 through 8.
It is commonly known as round-leaved moort or simply moort. This small tree is native to Western Australia; it’s found growing in the area between Albany and Esperance.
Moort grows best in loamy, in sandy or clayey soils often found around laterite.
These trees grow from 5 to 33 feet in height. They are 16 to 33 feet in width. Trees have a dense canopy. The leaves are a distinctive glossy, grey-green or green in color, concolorous and coriaceous and are elliptical to orbicular in shape. Moort have smooth bark that is grey-brown, light brown, or copper in color which turns grey as the tree ages. They are single-stemmed and form thickets. They may have a poorly developed lignotuber.
Elongated and flat peduncles are characteristic features of Moort. The buds are stalk-less having long, conically shaped caps that are clustered in groups of seven. The flowers are greenish-yellow or creamy-white flowers. The flowers are rarely red. In spring and summers, the flowers are obscured by dense foliage.
Eucalyptus platypus plants are usually used for ornamental purposes.
It is commonly known as Bald Island marlock or bushy yate. It is native to the south coast of Western Australia.
Bald Island marlock grows in sandy-loamy soil or in soils over quartzite or granite.
Bald Island marlock grows to a height of 7 to 26 feet. The bark is smooth and whitish-grey or grey in color. they grow in a bushy habit. Adult leaves are about 3.5 inches in length are 0.98 inches in width. They are elliptical, concolorous, glossy and light green in color. The flowers are yellow-green. Each axillary inflorescence has about 7 to 20 flowers. The sessile buds have fused hypanthia. Fruits of Bald Island marlock have an ascending disc along with three valves that are strongly exserted.
This plant is used for ornamental purposes. It is also used for erosion control and as a windbreak.
3. Eucalyptus Mallee
Mallee are low-growing shrubs. They look more like shrubs than they look like trees. They are multi-stemmed. They typically grow to a height of 10 feet but if the conditions are favorable, they can grow to a height of 25 feet. They fall under USDA hardiness zones 7a through 10b.
They are commonly known as sand mallee, tall sand mallee and Easter Goldfields homed mallee. They are native to Western Australia.
Sand mallee grows best in loamy, sandy and clayey soil.
Sand mallee has multi-stems that grow from a lignotuber. Single stem mallee is also found. It grows 7 to 26 feet tall. It is 13 to 26 feet wide. The habit of these plants is dense, upright, spreading, and open canopy. The bark of these plants is polished and smooth. The new bark that is exposed after shedding of dead bark is yellowish-brown in a color that becomes brownish-grey after maturation.
The leaves are grey-green in color. They are thick, stiff, and concolorous, having a distinctive arrangement. The leaf blade is elliptic shaped and has a narrow lanceolate. It is tapered at the base. Narrow-flattened or channeled petioles support the leaves. The flowers are cream-yellow-pink. A single axillary conflorescence has 3 to 7 flowered peduncles. Fruits are cylindrical or pear-shaped (pyriform) having a depressed disc and valves that are exerted. Fruits and flowers usually have a long tapering bud cap.
Eucalyptus eremophila are used for ornamental purposes. They make good, contrasting background plants in wide verges, parks, nature strips, and reserves. They are also used as a windbreak and for controlling wind erosion. They also attract insects and birds for nectar.
Eucalyptus erythronema is commonly known as red-flowered mallee, white mallee, white-barked mallee, or Lindsay gum. It is native to Western Australia.
White mallee grows best in sandy and clay soils with lateritic gravel.
White Mallee tree grows to a height of 7 to 20 feet. they can be single-stemmed or multi-stemmed, forming from a lignotuber. The bark is white colored. A new pale green bark is covered with a talc-like powder which is pinkish in color. the bark may be purplish, white, light pink, or salmon colored.
The adult leaves are thin and concolorous, having a distinctive arrangement. The leaf blade is in the shape of narrow lanceolate and tapered at the base. Petioles that are narrowly flattened or channeled support the petioles. Flowers are usually red but they can be creamy white, yellow, or pink. Each axillary conflorescence has 3 to 7 flowered umbellasters supported by peduncles.
They form great ornamental plantings. They are also used for the production of honey, products that are rich in tannin, and as a screening plant.
4. Decorative Eucalyptus
Some eucalyptus varieties are decorative and iconic. Eucalyptus pulverulenta, the silver mountain gum is loved by the florists. They provide interesting color to flower arrangements. These varieties are majorly used for ornamental purposes because of the shapes and colors of their flowers!
Problems with Eucalyptus Tree Varieties 🔥 TIP: !
Eucalyptus tree varieties are associated with certain problems which can be quite troublesome.
- Some varieties of Eucalyptus trees are invasive. This means that they grow out of their cultivation zone, into the wild. This shades out the native plants. an example of an invasive eucalyptus tree is Eucalyptus globules.
- Eucalyptus trees are rich in pungent oils. This makes them fire hazards when they are plated in groups.
Eucalyptus trees are extremely useful to humans. Essential oils extracted from them are used in medicines. Eucalyptus is said to hold significant health benefits like in cough, flu, insect bites, muscle and joint pains, and respiratory illnesses. Moreover, Eucalyptus has numerous household uses like as a component of cleaners, soaps, stain removers, carpet cleaners, etc. They are also an important source of timber in Australia. Different types of Eucalyptus offer different uses making this genus of plants extremely important to humans.
Related: Types of Dogwood | Types of Grevillea | Types of Germander | Types of Boxwood Shrubs
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The eucalyptus trees are native to Australia where the origins of this tree type can be found. Nowadays, there are many varieties of this tree family. These plants are present in a big variety with their distinct peeling bark and different foliage shapes and colors. Moreover, eucalyptus trees have a unique growth and emit pleasant aromatic fragrances throughout the year. Even though native to Australia, these trees can be planted anywhere. With the requirement that the conditions closely resemble their original native environment. Most of the eucalyptus trees grow at a very rapid rate compared to other trees. In fact, they are known as one of the 10 fastest-growing trees in the world. Some of these varieties can reach heights between 9 and 55 meters! 60% of their mass is grown in the first 10 years of their lifespan.
The eucalyptus tree bark shows its colorful beauty during the peeling process
It is worth mentioning that over the course of their evolution, eucalyptus trees have developed a unique survival method. This survival method even enabled them to survive the fires common to Australian forests. But how are eucalyptus trees able to do this? It’s due to a simple but genius plan of nature – these trees have dormant shoots deep inside their roots. This way, nothing can possibly damage or destroy them because nothing can reach them. The dormant eucalyptus shoots are thus well-protected and can only be activated through the heat in a case of fire.
Eucalyptus tree varieties
While varieties like the Gumtree and Silver-Dollar tree are the most popular amongst all eucalyptus types, there are some others that are also planted around the world. Here are several of them:
The lemon-scented eucalyptus is also known as the Corymbia citriodora. It originates from Northern and Central Queensland along the coast of Australia. This tree grows from 20 to 30.5 meters tall. The spread of its canopy is huge too, reaching up to 24 meters. The Corymbia citriodora tolerates drought well. In fact, it needs plenty of sunshine. It doesn’t even thrive in cold temperatures, as it is very susceptible to frost damage.
This tree is distinguishable by its first branch that tends to grow halfway up its height. The leaves of the lemon-scented eucalyptus are pale green, but they are evergreen and don’t change as seasons do. At the same time, its bark peels off with the change of time. It reveals a smooth, pale-white bark underneath which turns grey after some time. When crushed, the leaves of lemon-scented eucalyptus give off a pleasant lemon-like scent. Originally, this is the origin of its name. Among its other uses, the oil of this tree is widely used as an insect repellent. The wood of lemon-scented eucalyptus variety provides saw-timber, which is then used for general construction and wooden objects.
Tasmanian Blue Gum
The Tasmanian Blue Gum or the Eucalyptus globulus is one of the most popular varieties of the eucalyptus tree, widely grown all around the world because of their high adaptability. This eucalyptus variety is used to make cough drops and other medicines because of its aromatic and healing properties. Also, its wood is used for fuel and carpentry. Just like its cousin, the Lemon-scented variety, the Tasmanian Blue Gum grows quickly and up to 70 meters. It’s interesting that there are some registered specimens that are reported to be over roughly 152m. The bark of Tasmanian Blue Gum is known to be grey, green, or slightly blue. The trees require warm temperatures and soils that drain well.
Eucalyptus dives or the Peppermint eucalyptus tree is the smallest of eucalyptus varieties reaching “only” the height of 7.6 to 24.4 m. It originates from South-Eastern Australia where it is mostly used as a windbreak, planted in rows. The leaves of the Peppermint eucalyptus are light-green and just as the name suggests, they give off a nice peppermint scent, which the eucalyptus essential oils are mostly recognized by. Just like the other eucalyptus types, it requires soil that drains well. But unlike them, Peppermint eucalyptus tolerates both frost and drought fairly well.
Transgenic eucalyptus is a well-known variety that was created by combining genes from Brassica and eucalyptus. This interesting combination is widely sought after among tree planters because of its ability to grow 30% faster than the natural process. This means that within five to seven years, these plants are able to grow up to 30.5 m tall. While these characteristics make transgenic eucalyptus trees popular, some warn against their nature. They say these trees could easily overtake large amounts of land just like invasive kudzu do. However, this eucalyptus variety is favorable for the afforestation and quick plant replacement in areas that have been overly-deforested and need trees and greenery to sustain different species of animals and flora.
Planting eucalyptus trees
Since eucalyptus trees are fast-growing and quite adaptable, TreeCoin has recognized the potential of planting these trees to speed up afforestation and bring back the natural greenery of Paraguay. For this purpose, TreeCoin uses special varieties of eucalyptus types that have been cultivated in such a way that they would thrive in Paraguay’s environment. At the same time, they do not contain oil, which makes the trees fire-resistant. The eucalyptus benefits the environment by stopping deforestation as well as preventing global warming. Thus, it is very favorable for Earth as well as the future human generations. It’s time we start thinking green.
Known for its menthol-like smell and as a cut flower, eucalyptus plants can also make stunning container plants and showy annuals. These tough trees have numerous species available (over 700!), and most are native to Australia. Although these plants can reach over 200 feet tall, they can be used seasonally in many gardens, and even as a houseplant.
Most notably, eucalyptus is grown for its potent essential oils, which are commonly derived from the species E. globulus. These fragrant oils are used in many different ways—medicinally, for their cleansing properties, and to scent perfumes and fragrances. All parts of the eucalyptus plant produce these oils, but they are most commonly derived through steam distillation of the leaves. Because eucalyptus is rich in these compounds that are highly volatile, the plants are of some concern to firefighters because they can very quickly burn. On very hot days, forests of eucalyptus can be seen shrouded in a fog. This is actually caused by oil compounds of the plant becoming vaporized due to the heat.
See more fragrant houseplants.
Eucalyptus Care Must-Knows
Eucalyptus are easy, fast-growing plants, and they like well-drained, consistently moist soils. If you are planting one as a tree, be aware these are water-hungry plants. In a container, use any general purpose potting media, and make sure to plant them in a large pot. Eucalyptus are fast growers, and their roots can quickly fill a small container.
As far as exposure, eucalyptus need full sun, which helps plants grow sturdy and promotes better branching, brighter silver foliage, and higher oil content. If you are trying eucalyptus as a houseplant, or overwintering one, give it as much sun as possible in the home—usually a bright southern exposure will work best.
If you are planting eucalyptus in an area where they are hardy, the plant can become invasive. Studies show that eucalyptus trees may exhibit allelopathic affects on some species of plants, which is when a plant releases a toxin into the soil so that competing plants cannot grow. Black walnut is known for its ability to do this. There is still some uncertainty as to the level of allelopathic that eucalyptus trees are, but the speculation is something to consider when planting.
Eucalyptus trees are also notorious for being messy. As many species age, they shed portions of their bark, littering the understory. On the plus side, this exfoliating bark can be quite beautiful, especially during the winter. Some species, like E. deglupta, are grown almost primarily for their bark. This species is also known as the rainbow eucalyptus, and as the bark exfoliates, depending on the age, the plants color differently. So whole trunks can be varying shades of yellows, greens, reds, and purples.
Use eucalyptus to make a wreath!
Many species of eucalyptus have different-shaped leaves, depending on the maturity of the plant. Leaves may begin as round and coin shaped, then as the plants age, become long, lance-shaped leaves. Don’t be alarmed if you plant seeds and they aren’t quite what you expect. The trees may just need to grow into their proper shape.
More Varieties for Eucalyptus
Dwarf blue gum
Eucalyptus globulus ‘Compacta’ is a fast-growing tree that usually remains less than 30 feet tall, and it’s easy to keep trimmed to 10 feet tall. Leaves on immature plants are circular and blue; mature plants produce green sickle-shape leaves 6-10 inches long. Dwarf blue gum bears creamy-white flowers in winter, followed by bluish seed capsules in summer that drop from the tree, making this somewhat of a nuisance tree. Zones 9-11
Lemon scented gum
Eucalyptus citriodora is a large tree that grows 75-100 feet tall and spreads 25-50 feet wide. The tree has two forms of leaves: Juvenile foliage is rough and sandpapery; mature leaves are smooth and glossy. Both types of leaves produce a lemon-scent oil called citronella, which is widely used in perfumes. Lemon scented gum bears small white flowers in winter. Some experts have reclassified this tree as Corymbia citriodora. Zones 9-11
Eucalyptus deglupta gets its name from its multicolor bark. The tree sheds patches of bark irregularly to reveal green inner bark, which darkens with age to blue, purple, maroon, and orange. Also known as Mindanoa or Indonesian gum, it is a large tree, growing up to 200 feet tall and 40 feet wide. Zones 9-11
Red flowering gum
Eucalyptus ficifolia is one of the showiest of eucalyptus trees. It bears clusters of red, orange, pink, or white flowers above the tree canopy sporadically throughout the year. The tree grows 25-40 feet tall and wide. In recent years, botanists have reclassified it as Corymbia ficifolia, but you’ll often find it sold by its traditional name. Zones 9-11
Eucalyptus sideroxylon is called red ironbark because mature trees develop deeply furrowed reddish-brown bark. This tree may grow strongly upright to 80 feet tall, or it may be weeping in form and remain below 20 feet tall. The width ranges from 20-45 feet. Leaves on juvenile plants are bluish white and lancelike in shape. Mature trees produce sickle-shape leaves that turn bronze in winter. Flower color varies from pinkish white to red. Zones 9-11
Silver dollar gum
Eucalyptus cinerea is a small tree that grows up to 30 feet tall and 10-15 feet wide. The silvery leaves are round and gray-green, giving rise to the tree’s common name. As the plant ages, leaves become more oval and elongated. It is hardy in Zones 8-11 but may die back to the ground in severe winters. In colder Zones it can be grown as an annual, reaching up to 8 feet tall in a single season. Cut stems are often used in floral arrangements.
‘Silver Drop’ eucalyptus
Eucalyptus gunnii ‘Silver Drop’ is most commonly grown as an annual for its fragrant silver-green foliage. As an annual it grows 2-3 feet tall and wide. The species from which it is selected can grow to 40 feet tall and wide where it is hardy. Zones 8-11
Eucalyptus maculata is also sometimes classified as Corymbia maculata. It gets its common name from its irregular bark coloration. The bark sheds in flakes, leaving spots of white, gray, green, and pink. The tree bears white flowers in summer. In cultivation it reaches 60 feet tall and 30 feet wide. Zones 9-11
Sydney blue gum
Eucalyptus saligna is a fast-growing large tree that may reach 180 feet tall, but in cultivation it typically tops out at 50-60 feet tall and 25 feet wide. From late spring through summer it bears pink to white flowers, which attract birds. Zones 9-11
Eucalypts: 10 things you may not know about an iconic Australian
You’d be hard pressed to go more than 10 minutes without spotting a eucalyptus tree in Australia.
They dominate our landscapes from the bush to our backyards, paddocks, parks and pavements.
And they even have their own national day — on March 23.
Illustration of Eucalyptus obliqua (Wikimedia commons)
Illustration of Eucalyptus obliqua
They are extraordinary plants and many people love them.
One of those people is botanist Pauline Ladiges.
The world expert has been studying this iconic group of plants for the past 55 years.
“The most interesting thing for me is the diversity of the whole eucalypt group and its extraordinarily ancient history,” said Professor Ladiges from the University of Melbourne.
So how much do you know about this iconic plant? Let’s take a closer look.
What’s in a name?
The term eucalypt — meaning well (eu) covered (calyptos) — was first coined by French botanist Charles Louis L’Héritiert de Brutelle in 1788.
He examined the flower buds of a rough-barked tree from Tasmania’s Bruny Island collected on James Cook’s third voyage.
He named this species Eucalyptus obliqua. Commonly known as messmate, it is found right across south-east Australia.
The roots of the eucalypt go back to when Australia was part of the supercontinent Gondwana.
The oldest known examples of eucalypt fossils are 52 million-year-old flowers, fruits and leaves found in Patagonia.
52 million-year-old fossils of eucalypt fruits. (Supplied: Gandolfo et al/PLOS)
52 million-year-old fossils of eucalypt fruits.
Supplied: Gandolfo et al/PLOS
“There are some superb fossils that I don’t think anyone doubts that have been described from South America,” said Professor Ladiges.
“The eucalypt group has to go back beyond that because the fossils are so recognisable.
“They just look like fruits off a tree down the road.”
Sequencing of the eucalypt genome from the rose gum (Eucalypt grandis) — a species found in coastal areas of New South Wales and Queensland — indicates the group goes back at least 109 million years.
At that time, flowering trees were starting to take off and dinosaurs roamed the land.
A diverse Australasian
Today, botanists have identified around 900 species of eucalypts divided into three different groups: Eucalyptus, which make up the bulk of the species; Corymbia, the bloodwood eucalypts mainly found in the north; and Angophora.
Eucalypts come in all shapes and sizes and dominate the landscape from alpine regions to the outback and edges of rainforests.
There’s the mighty mountain ash (Eucalyptus regnans), the world’s tallest flowering tree; the gnarly snow gum (Eucalyptus pauciflora); the multi-stemmed bull mallee (Eucalyptus behriana); the apple or cabbage ghost gum (Corymbia flavescens) found in northern Australia; and the twisted Sydney red gum (Angophora costata).
“The only place they don’t really dominate is the very, very arid parts of Australia,” Professor Ladiges said.
But while we think of eucalypts as being uniquely Australian, there are also a handful of species in New Guinea, Timor, Sulewesi and even one species — the rainbow gum (Eucalyptus deglupta) — on the Philippine island of Mindanao.
Bark up the right tree
One of the most distinctive features of eucalypts is their bark.
Some trees have smooth bark — as the tree grows it sheds old layers from its trunk or branches. The new bark underneath is often brightly coloured that fades over time.
There are also half-barked trees that have thick bark around their trunk but smooth limbs.
“In some areas where a fire might be more like a grass fire, a lower storey fire, you’ll find trees there that only have rough bark at the base,” Professor Ladiges said.
An Aboriginal scarred tree in the Royal National Park, NSW (Wikimedia commons: Sardaka)
An Aboriginal scarred tree in the Royal National Park, NSW
Wikimedia commons: Sardaka
Other trees are completely covered in rough bark. The old layer of bark stays attached to the tree and forms a thick protective layer against fire. Rough barks can be a bit trickier to identify because the texture can take different forms.
If the bark has long stringy bark, it might a stringybark, if it has tough, blackened furrowed bark it might be an ironbark, and if it has really short fibres it might be a box or a peppermint.
But beware: not all trees with stringy bark are actually stringybarks, said Professor Ladiges.
There are about 30 species in eastern Australia that can be classified as stringybarks, but she said the word gets used for similar species that are not closely related.
The Darwin stringybark (Eucalyptus tetradonta) used in Aboriginal bark paintings in the Northern Territory is one of these false stringybarks.
Indigenous people across Australia also use bark to make canoes and shields.
In New South Wales, Victoria and Queensland there are a number of protected scarred trees. As the name suggests these trees bear scars from where the bark was cut away and sometimes engraved.
There’s oil and gold in them thar leaves
Leaves from the lemon-scented gum (Corymbia.citriodora) which is native to north Australia. (Supplied: Professor Pauline Ladiges)
Leaves from the lemon-scented gum (Corymbia.citriodora) which is native to north Australia.
Supplied: Professor Pauline Ladiges
A eucalypt’s leaves are packed with oil glands that produce the aromatic compounds that give us their distinctive scent.
“Some smell very strongly eucalyptus-like, some smell really like peppermints, and the lemon-scented gum has a more lemony smell,” Professor Ladiges said.
These compounds help protect the tree from attack by pests.
“Oil glands make them unpalatable to insects, but then you get insects that adapt to eating those sorts of leaves,” she said.
In 2013, biologists discovered that a yellowbox tree (Eucalyptus mellidora) in sheep paddock in New South Wales could change the smell of its leaves from one side to the other to protect itself against attack.
Scientists also discovered the leaves of trees in Kimberley contain microscopic traces of gold, using sophisticated imaging techniques.
X-rays of eucalypt leaves showing traces of different minerals including gold (Supplied: Mel Lintern/CSIRO)
X-rays of eucalypt leaves showing traces of different minerals including gold
Supplied: Mel Lintern/CSIRO
Eucalypt leaves also change over a tree’s lifetime.
The leaves of a young sapling are held horizontally to maximise the surface area for gathering light. As the tree ages, the stalk of the leaf twists so that the leaf becomes vertical and is not exposed to as much radiation.
But it’s not just the shape that changes, the structure changes, Professor Ladiges said.
“The anatomy inside changes. Instead of having an upper and lower surface both sides will have photosynthetic tissue,” she said.
This enables the leaves to maximise photosynthesis and minimise exposure to heat.
“They also have a lot of thick-walled cells, a lot of fibres. So they are really, really tough.”
They’re fruits not nuts
Illustrator and author May Gibbs brought whimsy to the eucalyptus fruit with her gumnut babies. (Wikimedia Commons)
Illustrator and author May Gibbs brought whimsy to the eucalyptus fruit with her gumnut babies.
It doesn’t have the same ring to it, but Snugglepot and Cuddlepie are technically gum-fruit babies.
“People call them gumnuts but they’re actually capsules which means that they open by valves at the top of the fruit. These valves dry up and open up and seeds drop out,” Professor Ladiges said.
These hard, woody capsules have a thick wall, which is not destroyed by heat. The capsules open up after fire to release the undamaged seeds.
Professor Ladiges said the shape and number of these capsules is distinctive from species to species.
Close up of fruits and flowers of the Mount Abrupt stringybark, found in the Grampians in Victoria (Supplied: Professor Pauline Ladiges)
Close up of fruits and flowers of the Mount Abrupt stringybark, found in the Grampians in Victoria
Supplied: Professor Pauline Ladiges
Reading the fire risk of the country
Features such as oil-filled leaves and bark that can easily shed make eucalypts highly flammable.
This ability to stoke a fire is part of their survival strategy, said Professor Ladiges.
“If a fire is hot but goes through fast it will do less damage than a really slow burning fire.”
“The fact that that helps fire go through fast was clearly a selective advantage to the species because then their seeds wouldn’t have been cooked.”
Even if the tops of the trees are destroyed by fire, many species can re-sprout from buds under their bark or from a lignotuber at the base of the tree. But not all species can re-sprout.
Alpine ash forests in the Victorian Alps after fire. (Supplied: Professor Pauline Ladiges)
Alpine ash forests in the Victorian Alps after fire.
Supplied: Professor Pauline Ladiges
A handful of species only regenerate from seed, which makes them very vulnerable to frequent, high intensity fires.
These species include the mountain ash (Eucalyptus regnans) and alpine ash (Eucalyptus delegatensis) in the Australian alps, and a group of species such as the salmon eucalypt (E. salmonophloia) in Western Australia’s wheatbelt.
“To certain degree you can read the fire risk of the country by what the eucalypts are doing because they’re the ones that have been around for a long time and they’ve taken the bet,” said David Bowman, an ecologist at the University of Tasmania.
“Should the tempo of fires suddenly increase when they’re immature, then they run the risk of becoming locally extinct,” Dr Bowman said.
This actually happened to alpine ash forests on the Australian mainland following the 2003, 2007, 2013, and 2014 fires.
“Some places got hit by three fires and had to do aerial sowing to recover.”
By gum, it’s kino
Many species of eucalypts ooze thick, red resin known as kino.
Recent research based on two Queensland species, the lemon-scented gum (Corymbia citriodora) and cadaghi gum (Eucalyptus torelliana), has shown eucalypt resin has antibacterial properties.
Resin has been traditionally used by Indigenous Australians to treat cuts and wounds.
While the most famous eucalypt-muncher is the koala, kino is an important food source for the yellow-bellied glider (Petaurus australis), a small tree-dweller that lives in the forests of eastern Australia.
Tree-dwelling yellow-bellied gliders are listed as vulnerable. (David Cook)
Tree-dwelling yellow-bellied gliders are listed as vulnerable.
The gliders only tap some trees to get their food so they have to move around large home ranges to find the right trees, said ecologist David Lindenmayer of the Australian National University.
Once they’ve found the right tree, usually a smooth bark species, they cut a distinctive v-shape into it to extract the sap.
“It’s a pretty miserable diet,” Professor Lindemayer told RN’s Offtrack.
“You have to do a lot of work to cut through the bark to get something that has low nutrient values.”
Not only is the sap like arsenic, it wears down the animals’ teeth very quickly.
“Most yellow-bellied gliders won’t last more than five or six years because basically their teeth are done,” he said.
Summer and winter
Eucalypt flowers have evolved to attract specific pollinators.
Most eucalypts flower in summer, Professor Ladiges said.
Manna gums flower in summer. (Supplied: Mike Bayly)
Manna gums flower in summer.
Supplied: Mike Bayly
“If you went down the coast now in Victoria you’d have messmate (Eucalyptus obliqua) and manna gums (Eucalyptus viminalis) flowering. And they’re basically pollinated by insects,” she said.
While these species of eucalypts have pale coloured flowers, others such as the Darwin woollybutt (Eucalyptus miniata) and the large-fruited mallee (Eucalyptus youngiana) are more brightly coloured.
These species flower in winter and are pollinated by birds.
“The colour is the stamens — the male part of the flower.”
Close up of Eucalyptus youngiana (Wikimedia commons: Gnangarra)
Close up of Eucalyptus youngiana
Wikimedia commons: Gnangarra
The flowering cycle also differs between species, with some flowering longer than others.
Some alpine ash eucalypts in the Australian alps are also starting to flower early in response to recurrent fires, Dr Bowman said.
What’s that eucalypt?
There are so many different species the best way to identify different species is to get a field guide for the local area, Professor Ladiges said.
While it may not help you put a name to the plant sitting on the verge outside your house, it will help if you go bush.
“Once people start getting their eye in for the bark, the fruit and the juvenile leaves they’re well on their way to identifying a plant.”
So go out bush and get closer to this iconic — and extraordinarily ancient — Australian.
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Garden plant of the moment: Eucalyptus
Evergreen foliage, gorgeous silvery leaves, and attractive peeling bark – three great reasons to love the eucalyptus. Native to Australia, this fast-growing evergreen tree looks great in any garden.
Choosing your eucalyptus tree
Many eucalyptus species don’t like the cold, but two that do are Eucalyptus gunnii (cider gum) and Eucalyptus pauciflora ssp. niphophila (snow gum). The cider gum grows fast, reaching an imposing 12m in height, so a better choice for small gardens is Eucalyptus gunnii AZURA, with the same silvery leaves but a more compact shape, growing into a bushy shrub around 2.5m high and wide. The snow gum is another relatively small eucalyptus tree, growing to around 5m high in 20 years.
All eucalyptus trees produce clusters of small fluffy pink or white flowers in summer which are enormously popular with bees, and their cream and white peeling bark looks good all year round. They do best in well-drained soil in full sun.
Caring for your eucalyptus tree
Because eucalyptus trees grow so fast, there are a few tips to bear in mind when planting them:
- Plant them when they’re small (ideally less than 1m/3.5ft tall), otherwise, they can become tall and leafy before their roots have established a firm base, leaving them top-heavy and unstable.
- Don’t enrich the soil with compost when planting, as this could promote leafy growth.
- Don’t stake the tree once you’ve planted it, as the roots will develop better if the tree is unsupported.
- Water regularly in dry periods for the first 2-3 years after planting.
It’s possible to grow eucalyptus trees in pots for a short period. Here’s how:
- Fill the pot with a mix of 70% loam-based compost (e.g. John Innes no 2 or 3) and 30% horticultural grit to improve drainage.
- Prune regularly during the growing season, and feed weekly with a high potash feed.
- Protect the pot in winter by wrapping it in horticultural fleece or bubble wrap.
- Don’t plant out a eucalyptus in the ground once it’s been in a pot for a while, as the roots won’t be able to establish properly and you could end up with a large, unstable tree in your garden.
Pruning eucalyptus trees
Eucalyptus trees should be pruned in late winter or early spring. To create a multi-stemmed shrub with lots of big silvery young leaves, cut back all stems to 5cm (2in) above ground level, or to the previous year’s stubs. This is called coppicing and works best on young plants.
If you’re not trying to keep your eucalyptus tree small, simply remove any side shoots and dead or crossing branches. Large trees can be pollarded to stop them getting too big, but this is a job best left to professional tree surgeons.
Pay us a visit and choose the tree that’s right for you. Our friendly staff will be happy to help!
Eucalyptus Tree Types: Popular Varieties Of Eucalyptus For Landscapes
Eucalyptus (Eucalyptus spp.) are native to Australia, but the quick-growing trees have been cultivated around the world for their attractive peeling bark and fragrant foliage. Although more than 900 species of eucalyptus trees exist, some are more popular than others in the United States. Read on for information about poplar eucalyptus tree types.
Eucalyptus Tree Identification
Trees of the genus Eucalyptus come in all sizes, ranging from short, bushy varieties to soaring giants. All share the pungent aroma for which their leaves are famous, as well as exfoliating bark. These are the qualities that facilitate eucalyptus tree identification.
Eucalyptus trees grow fast and generally live a long time. The many different species fall into several eucalyptus tree types.
Mallet Types of Eucalyptus Trees
You can divide eucalyptus tree types into categories related to their growth patterns. Some types of eucalyptus trees have only one trunk and notable space between branches. These open-branched forms are terms “mallet” eucalyptus tree varieties.
Recognize mallet eucalyptus tree varieties by the way the branches angle upward from the tree trunk, allowing light to filter between them.
Two popular mallet varieties are the sugar gum tree (Eucalyptus cladocalyx) and the red-spotted gum tree (Eucalyptus mannifera). Both grow to about 50 to 60 feet tall and thrive in the warmer USDA plant hardiness zones 9 through 10.
Marlock Eucalyptus Tree Varieties
Other varieties of eucalyptus trees offer denser foliage that often grows nearly to the ground. These types are termed “marlock” varieties.
If your tree is about 35 feet tall and offers lime-colored flowers and oval leaves, it is probably a marlock called round-leafed moort (Eucalyptus platypus). This tree is hardier than most eucalyptus tree varieties, growing happily in USDA zones 7 through 8.
Mallee Eucalyptus Tree Types
When it comes to eucalyptus tree identification, remember that shorter versions look more like shrubs than trees. These are termed “mallee” types of eucalyptus.
If your tree is under 10 feet tall, it is likely a mallee. Recognize this type by its many stems and bushy appearance, as well as its height.
Problems with Some Eucalyptus Tree Varieties
Some types of eucalyptus trees are invasive. This means that they escape cultivation and grow in the wild, shading out native plants. Blue gum (Eucalyptus globulus), for instance, is one such variety.
Another problem with eucalyptus trees is the fact that their leaves, full of pungent oils, can make them fire hazards when planted in groups or forests.
This profile has been superseded by the 2019 version, which is available here.
To view the complete Australian forest profiles series, click here.
Information for this profile is drawn from Australia’s State of the Forests Report 2013.
The term ‘eucalypt’ includes approximately 900 species in the three genera Eucalyptus, Corymbia and Angophora. Almost all eucalypt species are native to Australia. Eucalypts evolved from rainforest ancestors, adapting to an environment in which drought, nutrient-poor soils and fire were increasingly common.
Eucalypts have oil-rich foliage that burns readily, and they display a range of strategies to survive and recover from fire. The majority of eucalypt species are evergreen, retaining their leaves year-round.
Distribution and ownership
The Eucalypt forest type is found in all states and territories and across all but the continent’s driest regions (Map 1).
A total of 35 million hectares (38 per cent) of the Eucalypt forest type is in Queensland and 16 million hectares (18 per cent) are in New South Wales. Thirty-three million hectares (36 per cent) are on leasehold land and 26 million hectares (27 per cent) are on private land (Table 1). Seventeen million hectares (18 per cent) are on nature conservation reserves.
River red gum (E. camaldulensis) is the most widely distributed eucalypt, and is found in all Australian mainland states. The forests of south-eastern Australia contain a wide range of dominant eucalypt species, including major commercial timber species such as mountain ash (E. regnans), messmate stringybark (E. obliqua), alpine ash (E. delegatensis), silvertop ash (E. sieberi), blackbutt (E. pilularis) and spotted gum (C. maculata).
Eucalypt forest in south-western Australia are dominated by jarrah (E. marginata) and karri (E. diversicolor). Typical eucalypts of northern Australia include Darwin woollybutt (E. miniata) and Darwin stringybark (E. tetrodonta).
Many species of multi-stemmed mallee eucalypts are found across the inland regions of southern Australia. In inland arid zones, eucalypts are confined to the edges of rivers. Eucalypts are generally not found in the tropical and subtropical rainforests in eastern Australia, or in the warm and cool temperate rainforests of Victoria and Tasmania.
The Eucalypt forest type is divided into 11 forest classes based on the form of individual trees, crown cover and tree height. Eucalypts grow in two forms: single-stemmed trees and multi-stemmed mallee.
Eucalypt native forest comprises 80 million hectares of non-mallee trees and 12 million hectares of multi-stemmed mallee (Tables 2 and 3).
Sixty-six percent (53 million hectares) of non-mallee Eucalypt forest is woodland forest and 85 per cent (68 million hectares) is medium-height forest (Figure 1).
Mature mountain ash (E. regnans) trees are usually between 55 and 75 metres high and are an example of tall forest. Some mountain ash trees can grow to more than 90 metres, making this the tallest plant species in Australia, one of the tallest hardwoods, and one of the tallest flowering plants in the world.
Ninety-three per cent (11 million hectares) of mallee Eucalypt forest is woodland forest and 80 per cent (10 million hectares) is low forest (Figure 2).
Importance and uses
Eucalypt native forests are important for the conservation of Australia’s rich biodiversity. They support many forest-dwelling or forest-dependent species of flora and fauna. This includes species endemic to Australia and species that are listed as threatened under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.
Indigenous Australians have traditionally used nearly all parts of eucalypt trees. Leaves and leaf oils have medicinal properties, and saps can be used as adhesive resins. Bark and wood have been used for making vessels, tools and weapons such as spears and clubs.
Because of the size, wood quality and widespread distribution and abundance of eucalypts, eucalypts are a significant source of wood. The variability in wood colour, shape, hardness, weight, strength and durability makes eucalypt useful for many applications. Sawn wood is used in large-scale construction, general building, furniture-making and wood-turning. Engineered wood products such as laminated veneers, fibreboards and particleboards are used for construction and flooring. Eucalypt wood is also used for chipping, paper pulp and fuelwood. Oils distilled from eucalypt leaves are used for aromatherapy and in perfumes.
ABARES 2016, Forests of Australia (2013) v2.0, Australian Bureau of Agricultural and Resource Economics and Sciences.
Carnahan, JA 1990, Atlas of Australian resources, vol. 6, Vegetation, Australian Government Publishing Service, Canberra.
Montreal Process Implementation Group for Australia & National Forest Inventory Steering Committee 2013, Australia’s State of the Forests Report 2013, Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra.
Tallerack (Eucalyptus tetragona). Author’s photographs, except as noted
The planting of a tree is a gift, which you can make to posterity at almost no cost and with almost no trouble, and if the tree takes root, it will far outlive the visible effects of any of your other actions, good or evil.
George Orwell, 1946
Four-winged mallee (Eucalyptus tetraptera). Original painting by Annette Filice
Of all the foreign trees that have affected our landscape, eucalypts are undoubtedly the foremost, but, since their introduction into the Western United States in the mid-1850s, they have suffered their fair share of controversy. They were brought from Australia, where all but a few species are endemic, to be grown as horticultural oddities for the nursery trade, then later as promising forestry trees and possible saviors of a forecasted timber drought. The promotion of the genus by private landholders, commercial firms, and state and federal agencies over the last 150 years has resulted in landscapes in the West that are dominated by only a few species. In the regions where they are now conspicuous landscape features, they are either admired as aesthetically valuable heritage trees and monarch butterfly habitat, or demonized as America’s largest weeds.
Coral gum (Eucalyptus torquata)
Due to the well-documented, ecologically damaging characteristics of the few most commonly planted forestry species, primarily blue gum (Eucalyptus globulus), other eucalypts are regularly overlooked during the selection of plants for residential and commercial landscapes. The idea that these trees are all massive, fire-prone exotics— aggressive growers that overwhelm native plants and lower the water table—has made them so unpopular that they have almost completely disappeared in recent years from nurseries in the West.
Red-cap mallee (Eucalyptus erythrocorys)
The genus Eucalyptus, however, is large and diverse. With over 700 species, according to the most recent formal classification, eucalypts exhibit a great range of adaptations to different environments; they rival other large tree genera (eg, Ficus, Pinus, or Quercus) in expressing a variety of mature tree sizes. Many species never exhibit any of the problematic characteristics so commonly, and incorrectly, attributed to the entire genus.
Silver princess (Eucalyptus caesia subsp. magna)
Drought-tolerant eucalypts from desert and mediterranean climates of Western Australia rarely grow larger than small trees or large shrubs, shed little, if any, bark, and seldom reproduce in cultivation; they do, however, offer large, brilliantly colored flowers and attractive foliage. Many of these trees are rare in their native habitats and some are critically endangered. These species are the focus of this article—those whose planting should be considered as appropriate as that of Arctostaphylos, Ceanothus, Protea, and Grevillea; they deserve an opportunity to enhance the gardens, parks, and public landscapes of the Western United States.
Round-leaved mallee (Eucalyptus orbifolia)
A small, multi-stemmed species of Eucalyptus is usually referred to as a “mallee” in Australia. Such species have a number of characteristics that make them valuable horticulturally, including interesting foliage, beautiful flowers, and fascinating bark. Because of the dryness of the habitats in which they evolved, they tend to be extremely drought tolerant, with evergreen, sclerophyllous, often wax-covered leaves, which appear in different shapes as the plants mature. The bluish gray leaves of many mallees, including the commonly planted silver dollar tree (E. pulverulenta), are interesting and attractive enough to be regularly used by florists in cut flower arrangements. Depending on the species, mallees produce flowers ranging in size from smaller than a dime to larger than a silver dollar, with brilliantly colored stamens in vibrant yellows, vivid pinks, or stunning reds. Some sport beautiful reddish brown to salmon-colored bark of varying textures and patterns, including small vertical rolls that run parallel to the stems. Mallees are relatively easy to cultivate, propagate readily from seed, are hardy in moderate frosts, and respond well to pruning.
Mottlecah (Eucalyptus macrocarpa)
Three mallees with a mature height of six to twelve feet can be grown for their particularly attractive leaves and bark. Tallerack (Eucalyptus tetragona, syn. E. pleurocarpa), book-leaf mallee (E. kruseana), and round-leaved mallee (E. orbifolia) all occur in the wild in desert and mediterranean climates of southwestern Australia. All three species make eye-catching specimens with their opposite, distinctively grayish blue, silvery leaves. Tallerack is so covered with wax that it has nearly white leaves, stems, buds, and fruit. Book-leaf mallee’s smaller, orbicular leaves wrap around and stack tightly together on drooping stems. Round-leaved mallee, which is rare and endangered in the wild, offers slender, reddish brown stems with thin bark that peels vertically in fine cinnamon stick-like curls, contrasting beautifully with the tree’s silver leaves.
Three other small, sprawling eucalypts with particularly striking and unusual flowers are red-cap gum (Eucalyptus erythrocorys), bell-fruited mallee (E. preissiana), and silver princess (E. caesia subsp. magna). The name Eucalyptus is derived from the Greek words eu, meaning “well,” and kalyptos, meaning “covered,” referring to the flower buds, which are covered by a woody cap that falls off as the flowers open. Of all the eucalypts, none has a more brilliantly colored and prominent bud cap than red-cap gum, which sometimes goes by its aboriginal name, illyarrie. This spectacularly ornamental species, commonly grown in many areas of Australia, has a bright scarlet, four-lobed cap that is shed during flowering to expose four clumps of lemon yellow stamens. Bell-fruited mallee is an open, sprawling shrub with golden yellow flowers, sometimes as large as a silver dollar, shiny green, leathery leaves, and ornate, bell-shaped fruit. Rare in the wild, silver princess develops weeping, powdery white branches, from which hang flowers that combine crimson red filaments with yellow anthers.
Mottlecah (Eucalyptus macrocarpa) and four-winged mallee (E. tetraptera) both grow to about eight feet at maturity and are particularly distinctive for their large leaves and enormous, colorful flowers. With its wax-covered, silvery white, egg-shaped leaves, mottlecah rarely achieves a stature greater than that of a low-growing, depauperate shrub, but produces the largest and possibly most spectacular flowers and fruits in the genus. The bright red flowers can reach nearly four inches in diameter, and the fruits resemble white flying saucers. The robust, multi-stemmed four-winged mallee is a novelty wherever it is grown. Its thick, leathery, bright green leaves are prominently beaked at the tip; square, bright crimson flowers twist downwards, with fleshy wings protruding from each corner.
Bell-fruited mallee (Eucalyptus preissiana)
Coral gum (Eucalyptus torquata) and red-flowering gum (E. ficifolia, syn. Corymbia ficifolia) are larger than the species previously discussed, reaching maturity as small, single-trunked trees, yet no discussion of horticulturally valuable small eucalypts would be complete without their mention. Both are commonly grown in California (red-flowering gum much more than coral gum) and are useful anywhere a drought tolerant, well-behaved, small tree is needed. In addition, they make spectacular floral displays. Coral gum has a crown of lance-shaped, blue green leaves that emanate from orange branchlets; the curious lantern-shaped buds are coral pink with highly ribbed caps. Red-flowering gum is commonly grown, particularly as a street tree in the San Francisco area, yet is rare in the wild; its stout trunks are clad with rough, fibrous, gray brown bark under a dense crown of shiny, dark green leaves. During the summer, this species produces an impressive display of crimson, vermilion, pink, orange, or creamy flowers, which often completely cover the crown. The flower color varies with the selection grown and may be influenced by hybridization with the closely related, white-flowered marri (E. calophylla, syn. Corymbia calophylla).
The species pictured here and described above are only a few of the many smaller eucalypts that can be and are cultivated regularly in Australia and occasionally in the Western US. There are scores of other drought-tolerant mallees and small tree species from Western and South Australia.
Red-flowered gum (Eucalyptus ficifolia) in a California landscape
With rare exceptions, propagation of Eucalyptus is almost entirely from seed. Most species germinate readily and grow quickly into established plants. Usually, the tiny seeds are germinated in a finely grained potting mix in warm, bright conditions; young seedlings are carefully transplanted to individual pots. Saplings should be planted in an area with well drained soils in the fall; they will establish quickly if they are not allowed to completely dry out in their first winter and are protected from freezing while young. Many mallees can become straggly and develop a poor form with age. Pruning heavily to ground level every ten years or so will produce a vigorous regrowth and a more attractive plant, with renewed flower production. The best way to acquire seeds is from online vendors, such as the Cal Poly Plant Conservatory (www.plantconservatory.calpoly.edu) and Windmill Outback Nursery and Nindethana Seed Service in Australia.
Book-leaf mallee (Eucalyptus kruseana)
Eucalypts are among the most well-known and recognizable trees in many parts of the world where they have been propagated for timber, fiber, fuel, and windbreaks. The usefulness of the genus in some kinds of forestry is beyond question. The ornamental value of smaller eucalypts is far less well known—especially outside Australia. In fact, most people would not easily recognize some of the species described here as eucalypts. Due to the diversity of foliage, flowers, fruit, bark, and form, and the ease with which they can be grown in dry climates, mallees can be useful and decorative landscape plants. By planting smaller, more well behaved, ornamental species of Eucalyptus, we may finally erase the bad name earned by the large, weedy members of the genus.
Phonetic Spelling yoo-kuh-LIP-tus sin-EER-ee-uh This plant has high severity poison characteristics. See below Description
Eucalyptus cinerea is a small evergreen tree or shrub native to Australia. It can grow rapidly (6-8 feet in one season). The leaves are round, fragrant and an attractive silver color, hence the common name, silver dollar tree. The bark is reddish brown and peels on smaller stems and becomes gray and stringy on the trunk as the tree matures.
In its native environment, it can reach 60 feet. It is not reliably cold-hardy, but often comes back during the growing season, even after a hard freeze. In cold climates these plants are commonly grown in containers as either shrubs or annuals. Container plants can be placed on patios or sunk into the ground, but must be brought indoors in fall before first frost for overwintering.
This plant is moderately salt- tolerant. It is grown primarily for its foliage but rarely produces flowers. The foliage is fragrant and is frequently used in floral arrangements.
Minor skin irritation can occur when handling bark or leaves. Plant oil is extremely toxic, especially if large quantities are ingested.
Insects, Diseases, and Other Pest Problems: No serious insect or disease problems.
Quick ID Hints:
- Opposite, round, sessile, blue-green leaves
- Leaves/stems emit eucalyptus odor when bruised
Small shrub to large tree, up to 52.5′ tall.
The Eucalyptus genus has 2 leaf morphologies- adult and juvenile; in zone 7b, specimens usually do not survive to the adult stage, so the leaves that we see are the orbicular, sessile, opposite juvenile leaves; bruised bark and leaves give off a characteristic eucalyptus odor; dried leafy branches sometimes are used in floral arrangements; in Australia and New Zealand, eucalyptus species are referred to as ‘gums’.
Drought tolerant when established; intolerant of mild winters and early/late freezes; prefers full sun and well-drained soil.
More information on Eucalyptus.
Cultivars / Varieties: Tags: #fragrant#evergreen#poisonous#drought tolerant#foliage#silvery#container plant#gray leaves#silver leaves#fragrant leaves#cut flowers#salt tolerant#dried arragements#flower arragments#fantz
For the more considered gardener, it may help you to begin the decision making process by answering the following questions; make a wish list by jotting down your answers. Armed with a better understanding of what you’re looking for, you can then visit the Shop Page and use the filters to help you narrow down the choices.
What kind of Eucalyptus do you want (what job do you want the tree to do)?
a) A beautiful stand-alone specimen/feature tree
b) A small tree ideal for smaller urban gardens
c) A tree to cast shade – one to sit under or to cast a protective umbrella over shade loving plants
d) A fast growing evergreen screen – single specimen, e.g. to screen a barn from view
e) An evergreen hedge- several metres long. Eucalyptus will form a loose but effective ‘hedge’
f) Cut foliage for flower arranging – grow it as a large shrub
g) A tree for firewood production – coppice or clear fell?
h) Growing in a container – choosing an evergreen tree for a patio or courtyard garden
How big do you want your tree or screen to grow?
Question: Are you going to allow it to develop to its maximum potential (given your growing conditions) without any pruning or do you intend to do a little trimming now and then to keep it under control?
Trimming ‘a little and often’ is best with a specimen tree, to give it a nice shape. See pruning and training.
As with any tree planting exercise, please ensure that your tree will have plenty of space to grow, free from buildings and that it will not upset the neighbours. Refer to our: distance from buildings section (opens a new page).
What is your growing environment like?
Consider the following:
Your garden climate: frost pocket, windy/exposed, coastal (salty) or warm/sheltered
Your garden soil assessment: Boggy or Standard garden soil or Dry Fertile soil or Poor/Stony/Sandy Acid (you can grow Rhododendrons) or Neutral or Alkaline/Chalky
Additional Features you may like to consider:
Aroma of the leaves: the smell and sound of the foliage are a pleasant sensory addition to any garden
Winter interest: bark detail and foliage
Leaf colour: both new growth and winter foliage
Flowers: the majority of hardy Eucalyptus flowers are white/creamy white, they tend to be prolific and rich in nectar favoured by bees and other pollinators, which is a ‘good thing’
Armed with your ‘design brief’ you can now tackle the list of species with confidence and match a tree with your wish list
Still unsure? Send us an email and we will try and help you reach a decision.
Download our Screening Tree Guide
Grab a cup of coffee, pen and paper and download our Really Handy Guide on how to choose a Screening Tree
Eucalyptus is a genus of the myrtle family, Myrtaceae, and is native to Australia. There are over 700 varieties of eucalyptus known to date – most of which are common to Australia. There are only 15 varieties of eucalyptus that naturally occur outside Australia.
Almost all eucalyptus are evergreen and the leaves are covered with oil glands. The natural oil contains powerful disinfectants and can even be toxic. Koala Bears are intolerant of the oil and eat the leaves in vast quantity. Eucalyptus oil is used to make cleaning products, deodrants, cough sweets and toothpaste.
In the wholesale flower markets, eucalyptus is one of the most popular foliages used by florists because of it’s pleasent smell & the fact that it bulks out well in any flower arrangement. Eucalyptus is especially popular for it’s use in wedding flowers, with the new 40cm mini varieties fast becoming a favourite.
Most eucalyptus is sold by weighted bunches, but the 200gm is now stem counted and sold in buckets of 50 or 100 stems. The heavier grades are sold in 300, 400 and 500gm bunches – most being no taller than 60cm in stem length.
You can buy wholesale eucalyptus on our Web-Shop by clicking here.