Eucalyptus (Eucalyptus sp.)
Eucalyptus is from the large Myrtaceae family. These aromatic trees are native to Australia and only about 12 of the many species grow in the warmer regions of Europe. Eucalyptus are often also known as gum trees because they sometimes exude a red resin from breaks in the bark.
Common name: eucalyptus, gum tree
Scientific name: Eucalyptus sp.
UK provenance: non-native
Interesting fact: eucalyptus oil is highly flammable, and fires travel easily through large plantations, especially in Australia where the weather is hot. However, reports that eucalyptus trees can spontaneously combust are untrue.
What does eucalyptus look like?
Overview: they can vary in form from a short shrub to a tall evergreen tree. The bark is a blue-grey colour and peels off in strips revealing yellow patches underneath.
Leaves: best identified by the blue-green adult leaves that are long and slender and hang downwards from single stalks. Juvenile leaves on younger trees are blue, round and unstalked. Eucalyptus oil comes from the adult leaves which exude the unmistakable scent when crushed.
Flowers: flower buds are cone-shaped and grouped together in sets of three on short stalks. Each bud has a round cap on top called the calyptus, which falls off to reveal the fluffy white or red flower stamens that are so attractive to bees.
Fruits: in the middle of the flower a hard, woody pod develops that opens to release seeds.
Look out for: young leaves are usually stemless and rounded. Adult leaves are long and stalked. When crushed, leaves have a distinctive smell. Flowers look like tassels of stamens, opening a year after buds are formed.
Could be confused with: two of the most common species of eucalyptus in the UK are the cider gum (Eucalyptus gunnii) which can be found in great numbers on the Essex coast, and the Tasmanian blue gum (Eucalyptus globulus) which is the main source of eucalyptus oil and grows plentifully in Cornwall and Ireland.
Identified in winter by: eucalyptus is evergreen so its leaves are present year round.
Where to find eucalyptus
Eucalyptus are fast-growing trees and are widely planted in gardens, parks, amenity areas and forestry plantations. It has become naturalised in woodland and on roadsides in southeast and lowland England. Some species occasionally regenerate from seed in the UK.
Value to wildlife
Eucalyptus attracts bees and other pollinating insects. Leaves have a have a high level of essential oils which are difficult for most animals to process.
Famously, in Australia, it is the choice food of koalas.
Mythology and symbolism
Australian indigenous populations used eucalyptus for spiritual cleansing. Eucalyptus oil is widely known for its medicinal properties, which has added an air of magic and mystery to the reputation of the tree.
How we use eucalyptus
Australian indigenous populations had many uses for eucalyptus trees. They used the wood and bark to make tools, spear throwers, shields, canoes, musical instruments. Leaves of certain species were soaked in water making a healing tea. The Kulin people of Victoria made water bowls from the tree known as tarnuks. The Murray river tribes were known to use the bark to make canoes.
Oil from the leaves of eucalyptus trees is now used all over the world for its antiseptic qualities. It's used medicinally to help clear congestion and colds. It also appears in some topical creams for arthritis and insect repellents.
Most commonly the wood from tree is used for timber and pulpwood for paper production.
There are not many threats to eucalyptus but it can suffer from eucalyptus gall wasp. The larvae of the gall wasp develop inside raised galls on the leaves which can result in excessive leaf wall.